It’s easy to overlook the enormous impact that satellites have on our daily lives. Without them, many essential services that we take for granted, such as long-range weather forecasts and navigational systems, would be impossible. Satellites have also revolutionized modern warfare, enabling us to gather intelligence and monitor enemy movements from afar. They even play a crucial role in providing internet access in war-torn regions and documenting evidence of war crimes.
However, despite the significant role that satellites play, the general public often has limited knowledge about them. This is why we have compiled a guide to address the most commonly asked questions about satellites.
What is the definition of a satellite?
A satellite refers to a man-made entity that is propelled into space at a high enough velocity to maintain a consistent orbit around a celestial body. When it comes to our planet, this required velocity, also known as the first space velocity, measures around 7.8 km/s.
What is the number of active satellites in space?
As of the start of 2022, approximately five thousand operational spacecraft are orbiting the Earth. Roughly half of these satellites belong to Starlink and OneWeb, which have been specifically deployed to provide worldwide Internet coverage.
What are the different altitudes at which satellites orbit?
Satellites can be placed in various orbits depending on their intended use, with altitudes ranging from a few hundred kilometers to hundreds of thousands of kilometers. The minimum altitude for satellite flight is determined by the presence of Earth’s atmosphere, as the closer a satellite is to the planet’s surface, the more it will be affected by atmospheric drag.
When a spacecraft is at an altitude of 200 kilometers, it will only stay in orbit for a few days without constant course corrections. Objects in a 400-kilometer orbit, such as the ISS, typically remain in space for about a year. However, satellites in orbits higher than 800 kilometers are not significantly affected by the Earth’s atmosphere and can stay in space for thousands of years.
What determines the size of satellites?
The size of satellites is dependent on the payload capacity of launch vehicles and the dimensions of their cargo compartment. Currently, the heaviest commercial satellites in Earth’s orbit weigh around 7 – 8 tons (excluding the ISS and the Chinese orbital station). Typically, these satellites are used for communication and space observation purposes. It has been reported that the latest versions of the American KH-11 optical reconnaissance satellites can weigh as much as 17 – 19 tons.
Simultaneously, there is a significantly greater quantity of smaller satellites for every one of these “giant” satellites. Take, for instance, the Starlink satellites (the most massive serial spacecraft ever created) which weigh between 260 and 300 kg, depending on the specific version.
However, there is still room for improvement. The continuous progress in miniaturization and electronics has opened up new possibilities for shrinking the size of satellites. As a result, it is now feasible to develop fully functional spacecraft that are no larger than a standard printed circuit board. One remarkable example of this is the Sprite femtosatellites, which weigh only 4 grams and have a diameter of 3.5 cm. What’s even more astounding is that these satellites can be manufactured for less than 100 dollars.
What is the reason for satellites having various orbits?
The choice of orbit for a satellite depends on its intended use. In the case of satellites aimed at capturing images of the Earth’s surface, they are placed in low orbits to achieve the highest image resolution. Global positioning systems typically use orbits with altitudes of around 19-21 thousand kilometers. Communication satellites and weather monitoring satellites, on the other hand, are generally positioned in geostationary orbits. More information about different types of near-Earth orbits can be found here.
A geostationary orbit is an orbital path that circles above the equator of the Earth, situated at an altitude of approximately 35,000 kilometers. The satellite positioned within this orbit revolves around the Earth at the same speed as its rotation on its axis. Hence, from the perspective of an observer on the ground, the satellite remains fixed in the sky, enabling the precise alignment of a stationary antenna on the ground. Consequently, the geostationary orbit proves to be an optimal location for deploying vehicles dedicated to relaying television and radio signals, monitoring weather conditions, and analyzing solar activity.
In contrast to other orbits, the geostationary orbit has a limited “capacity”. Satellites that use the same or similar frequency bands must be positioned at a significant distance from each other to prevent signal interference. International regulations allocate specific sections of the geostationary orbit to each country. These countries have the option to use the allocated section independently or to sell or lease it to others. Many countries choose to monetize this resource, using it as a means to supplement their budgets.
What is the source of power for satellites?
In the early days, satellites relied on chemical batteries for power. However, engineers quickly transitioned to using solar panels as their primary source of energy. Nowadays, almost every spacecraft is equipped with solar panels. It is interesting to note that in the past, certain Soviet reconnaissance vehicles were powered by nuclear reactors, but this practice was eventually discontinued.
What is the fate of decommissioned satellites?
Decommissioned satellites transform into space debris, presenting a potential hazard to other spacecraft. The situation is relatively manageable for satellites in low orbit as they will eventually disintegrate in the Earth’s atmosphere. Nevertheless, the scenario becomes significantly more intricate for vehicles in higher orbits.
For geostationary orbit, current regulations necessitate that satellite operators transfer older satellites to a higher orbit (known as a disposal orbit) once they have reached the end of their operational lifespan. This ensures that they do not pose any risk to nearby satellites.
What is the maximum resolution at which satellites can capture images?
The resolution of satellite imagery is determined by various factors, including the satellite’s orbital altitude and the capabilities of its cameras. Presently, the highest resolution achievable by commercial satellites is approximately 25-30 cm. However, it should be noted that this limitation is not due to technical constraints, but rather regulatory restrictions. For instance, in the United States, it is forbidden to publicly release satellite images with a resolution exceeding 25 cm.
Regarding military vehicles, the exact resolution of their cameras is classified information. However, some estimates suggest that the U.S. KH-11 series reconnaissance satellites have the capability to capture images with a resolution of at least 10 centimeters.
What is the lifespan of a satellite?
The lifespan of a satellite depends on various factors such as its orbit, purpose, and fuel capacity. Generally, modern satellites are known for their high reliability. Often, satellites are retired not due to equipment malfunctions, but because they have depleted their fuel reserves necessary for maintaining their operational orbit. This is why many companies are currently researching and developing specialized space refueling technologies to prolong the service life of older satellites.
Is it possible to destroy a satellite?
A satellite can indeed be destroyed by using an anti-satellite missile. Over the past few years, several countries, including Russia, the United States, China, and India, have conducted successful tests of such weapons, effectively striking their intended targets in orbit.
There are various methods that can be utilized to eliminate satellites. For instance, the Soviet Union had a program known as the “Satellite Fighter” where they launched “kamikaze” vehicles into space. These vehicles were intended to approach an enemy satellite and detonate, causing damage with fragments.
Earth is positioned as the third planet from the Sun, making it the third farthest planet in the solar system.
As part of the solar system, Earth, Mercury, Venus, and Mars form the group of terrestrial planets.
Earth possesses a natural satellite known as the Moon, as well as numerous artificial satellites, with the International Space Station being the largest.
Venus and Mars are Earth’s neighboring planets.
The Earth’s outer layer is primarily made up of silicates, forming a rigid shell. The lithosphere is comprised of the solid crust and the viscous upper portion of the mantle. Below the lithosphere lies the asthenosphere, which is characterized by its relatively low viscosity, hardness, and strength in the upper mantle. The Earth possesses a distinct liquid outer core and a solid inner core.
Out of all the planets that we know of, Earth is the only one that exhibits active plate tectonics.
Orbit of the Earth
The distance between the Sun and the Earth averages around 150 million kilometers (1 astronomical unit).
The point in the Earth’s orbit closest to the Sun, known as perihelion, is approximately 147.098 million kilometers (0.983 astronomical units).
The point in the Earth’s orbit farthest from the Sun, known as aphelion, is approximately 152.098 million kilometers (1.017 astronomical units).
The average speed at which the Earth orbits the Sun is 29.783 kilometers per second.
It takes the Earth approximately 365.26 days to complete one revolution around the Sun.
A day on Earth lasts for 23 hours 56 minutes 4.1 seconds.
The Earth rotates in the same direction as the other planets in the Solar System, except for Venus and Uranus.
Unique Physical Characteristics of Our Planet
Our planet, Earth, stands as the fifth largest celestial body in our Solar System.
Our planet’s surface experiences a wide range of temperatures, from a bone-chilling -89.2°C to a scorching hot +56.7°C.
The Earth boasts an equatorial radius measuring 6378.1 kilometers, providing a sense of its vastness.
Covering a staggering 510.072 million square kilometers, the Earth’s surface area is an awe-inspiring sight.
With an average density of 5.5153 grams per cubic centimeter, our planet possesses a solid and substantial core.
As gravity exerts its force, the acceleration of free fall on Earth is measured at 9.78 meters per second squared, equivalent to 0.99732g.
The Earth’s mass is an astonishing 5.9726 x 10 24 kilograms, a testament to its immense size and influence.
Broadcasting the Earth from space online
Earth’s Atmospheric Composition
The composition of the Earth’s atmosphere consists primarily of nitrogen (78.08%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.04%). It may also contain 0.1 to 1.5% water vapor depending on the climate.
The average atmospheric pressure on Earth at sea level is 1 atmosphere (101.325 kPa).
About three-quarters of the atmosphere’s mass is located within the first 11 kilometers of the Earth’s surface.
The Earth’s atmosphere does not have distinct boundaries; instead, it gradually becomes thinner and thinner as it transitions into outer space.
The Earth’s atmosphere is divided into different layers based on density, temperature, and composition. These layers include the troposphere, stratosphere, mesosphere, thermosphere, ionosphere, and exosphere.
Climate of the Earth
The Earth’s climate experiences seasonal variations due to its axial tilt angle of 23.44 degrees.
As one moves towards higher latitudes, the amount of solar energy reaching the Earth’s surface decreases.
The Earth can be divided into different climatic belts, which are natural regions with similar climates.
In the Keppen classification system, the type of climate is determined based on the vegetation found in a particular area. This system consists of five main climate zones (tropical rainforest, desert, temperate, continental, and polar), each further divided into more specific subtypes.
The water cycle plays a crucial role in sustaining life on land.
Sea currents play a crucial role in shaping the Earth’s climate, just like the thermohaline circulation, which is generated by variations in water density and facilitates the transfer of heat energy from the equator to the poles.
The Earth’s Topography
About 70.8% of the Earth’s surface is covered by the world’s oceans.
The continents feature rivers, lakes, groundwater, and ice, and together with the oceans, they form the hydrosphere.
Underwater, there are mountains and a network of mid-ocean ridges, as well as submarine volcanoes, oceanic trenches, submarine canyons, oceanic plateaus, and abyssal plains.
On land, various types of relief can be observed, including mountains, deserts, plains, plateaus, and more.
The Earth’s polar regions are enveloped by a layer of ice, which includes the Arctic sea ice and the ice sheet of Antarctica.
Fascinating details about our planet
Earth is the most extensively studied celestial body in our solar system and the singular known habitable planet according to scientific knowledge.
Earth is the most compact planet in our solar system.
Earth took shape from a solar nebula approximately 4.5 billion years ago.
The gravitational pull of the Moon is responsible for the occurrence of ocean tides on Earth.
Earth is home to approximately 8.7 million species of living organisms, and humans are just one among them.
The Earth’s surface has been in a constant state of flux: continents have emerged and disappeared, drifting across the face of the planet, converging to form a supercontinent, and then separating into isolated landmasses.
The initial individual to witness Earth from the cosmos was Yuri Gagarin in 1961.
From the outer space and from celestial bodies beyond the orbit of Earth, it is feasible to perceive the progression of our planet through phases reminiscent of those of the moon.
Understanding Satellites
A satellite is a celestial body that orbits around another celestial body within a defined path in space. There are two types of satellites: natural and artificial, depending on their origin.
The Earth has a natural satellite called the Moon
There are two prevalent explanations for the origin of natural satellites
The Moon, being a natural satellite, revolves around the Earth
- According to one theory, a planet attracts an asteroid with its gravitational force, causing the asteroid to start orbiting the planet and eventually become spherical in shape.
- In the second theory, it is proposed that during the formation of a planet, a portion of it breaks off and remains in orbit around the planet.
The second theory is considered to be applicable to the Moon. Scientists have discovered that the Moon and Earth share the same elements in their compositions. This has led them to hypothesize that the Moon was once a part of the Earth.
The Earth’s only natural satellite is called the Moon, and this fact is widely accepted today. However, during the 19th and early 20th centuries, astronomers often speculated about the existence of other satellites orbiting the Earth.
Possible natural satellites of the Earth
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A bolide is a meteor that is bright and easily visible.
A scientific article reveals that a new discovery has been made:
The Earth was believed to have 3 small satellites, according to Georg Waltemath’s hypothesis. Many scientists had observed these satellites at various times, but they were mistaken for sunspots. Waltemath explained that satellites are generally not visible because they reflect very little light. However, he managed to calculate the specific time when a satellite would pass through the Sun’s disk and become visible. Scientists Winkler (Jena, Germany) and Ivo von Benko (Pula, Austria) verified his hypothesis, but unfortunately, they did not see the satellite at the expected time.
There have been other claims of Earth satellite sightings as well. These claims were made by astrologer Hornold, amateur astronomer Spiel, and scientist John Bugbee. However, none of these claims have been confirmed.
Quasi-satellites
Cruithne is a type of celestial body known as a quasi-satellite, rather than a true natural satellite of the Earth.
Artificial satellites
GLONASS is a global navigation satellite system, which is a product of Russian innovation.
An artificial satellite of the Earth is a spacecraft that revolves around the planet in an elliptical trajectory. Typically, this term is used to describe unmanned vehicles.
There are numerous satellites in outer space, including communication satellites, reconnaissance and navigation satellites, meteorological satellites, astronomical satellites, and other research satellites.
What to watch that’s fascinating about the universe
There are numerous captivating materials about space these days that anyone can enjoy, even if they don’t have any knowledge about the subject. If you have an interest in space, Beautiful World suggests checking out the following:
Let’s gaze into the night sky and try to count the number of satellites orbiting Earth. How many visible satellites does Earth have? Go ahead, give it a try! You probably haven’t attempted it yet because you know that we only have the moon nearby. However, it’s strange to think that Jupiter boasts a family of 67 satellites. How are we any less impressive?
Earth only has one satellite, known as the Moon.
Is it really accurate to say that there is only one satellite orbiting the Earth? Technically, yes. However, it is possible that in the past, there may have been other satellites in close proximity. This theory is supported by the unusual landscape on the far side of the Moon, which could have been caused by a collision with another satellite.
Satellites are not known for their longevity. For instance, Mars currently has two satellites, but this will not always be the case. One of them, Phobos, is gradually getting closer to the planet and will eventually collide with it. This is expected to happen in approximately 10 million years.
Maybe at some point in the future, we will include more celestial bodies to the roster of Earth. Take, for instance, Triton, the largest moon of Neptune, which spins in the opposite direction and stands out from the rest. Scientists speculate that the planet was likely captured by the gravitational pull of Triton from the Kuiper belt.
The orbit of asteroid 2006 RH120.
It may come as a surprise, but our planet had actually ensnared asteroid 2006 RH120 in 2006-2007 before it made its escape. Additionally, there are satellites that elude our detection due to their positioning, distance from Earth, and small size. Even millimeter-sized asteroids can be found in the Earth’s orbit.
Are there a greater number of satellites in orbit around Earth?
Exactly how many satellites are currently orbiting Earth? There are several significant celestial objects that exist in close proximity to our planet. One such example is Asteroid 3753 Cruithnee, which maintains an orbital resonance with the third planet from the Sun. Although its path is erratic, it completes a full orbit around the star in one year. This particular asteroid was first identified in 1986, and numerous other objects have been detected since then.
2007 TK7 is a unique asteroid that is currently in a stable orbit with our planet.
As you may already know, the Earth has one moon, but that could change in the future as we discover and potentially acquire more satellites. For now, let’s appreciate the beauty of our closest celestial companion.
The mysteries of space captivate humanity, leading to the creation of various instruments and technologies to explore the solar system. Not only are there artificial satellites orbiting the Earth, but there are also natural satellites that have been studied for a long time.
The distinction between natural satellites and space debris
In technical terms, a satellite can be defined as any object or celestial body that orbits the Earth. They are often mistaken for debris that has arisen as a result of human activity. Fragments and various particles left over from spacecraft repairs orbit the Earth at high speeds. These objects, in the form of scraps of metal and other rubbish, serve no useful purpose and are categorized as orbital debris, which includes:
- Components from rocket explosions;
- Abandoned objects;
- Tools accidentally dropped by astronauts during repairs.
The distinction between space debris and natural satellites lies in their origin. Space debris is the byproduct of human activity, whereas natural satellites form organically.
In order to examine the lasting consequences of collisions with space debris, NASA devised a unique satellite known as LDEF. Over the course of its 6-year mission, LDEF encountered over 20,000 collisions with orbital debris and micrometeorites.
Ongoing analysis is being conducted on the data collected by the device, and Japan is currently constructing a large net to capture space debris.
Natural satellites
Natural satellites are celestial bodies that occur naturally and orbit planets. There are two prevailing theories regarding the origins of these bodies:
- During the planetary formation process, a fragment broke away from the planet and entered into orbit around it.
- An asteroid was drawn towards Earth by its gravitational force, eventually settling into a stable orbit and assuming a spherical shape.
Researchers have discovered that the Earth and the Moon share similar chemical compositions, leading to the hypothesis that the Moon was once a part of our planet. In the 19th and 20th centuries, astronomers believed that the Earth had multiple types of satellites. However, it is now widely accepted that the Moon is the only natural satellite of our planet.
Quasi-satellites: Earth’s Resembling Celestial Bodies
In the 21st century, a remarkable discovery was made – celestial bodies that bear a striking resemblance to satellites and are in a 1:1 orbital resonance with our planet, Earth. These peculiar entities were given the name quasi-satellites, as they orbit the Sun and maintain the same distance from it as our home planet. Due to the inherent instability of their orbits, these quasi-satellites occasionally come close to Earth. They are often referred to as a second moon or second satellite.
However, this simplified nomenclature has led to some confusion. For a period of time, Cruithni, a well-known quasi-satellite, was mistakenly referred to as a second satellite.
Among the numerous quasi-satellites, there is also the smallest known one called Duende, which measures a mere 30 meters in diameter. In the year 2094, this petite celestial body will be visible to the naked eye from a distance of 4500 km away from Earth, without the need for any modern devices. The list of these quasi-satellites is quite extensive.
Artificially Launched Objects
Objects that are sent into space and orbit around our planet are known as artificial satellites of the Earth (ISE). In order to achieve orbit, these objects must have a velocity equal to or greater than the initial space velocity. Their flight takes place at altitudes of up to several hundred thousand kilometers. The lower limit of this altitude range is determined by the need to avoid rapid deceleration in the Earth’s atmosphere.
The length of time the object orbits depends on the average altitude it is flying at and can range from 1.5 hours to several years. Satellites in geostationary orbit complete one full rotation every twenty-four hours and appear stationary in the sky to the naked eye. One advantage of this type of orbit is the ability to attach non-spinning parts to antennas.
Objects circling the Earth include not only unmanned vehicles but also manned spacecraft, automated cargo ships, and space stations. The unmanned devices can vary in size and weight. Some are designed for one-way missions while others can be partially or fully returnable.
We carried out a test: we inquired from our acquaintances whether they were aware of the number of satellites present around the Earth. Out of a group of ten individuals, only a single person chose to clarify: “Which ones? Natural or artificial?”. The remaining respondents recollected that the Earth indeed possesses one satellite, namely the Moon, and they had also heard about a few others. In order to address any uncertainties surrounding this matter, Wonderful World has decided to provide an overview of the Earth’s satellites and their distinguishing characteristics.
Definition of a Satellite
A satellite is an entity that orbits around another celestial body in space following a specific path. Satellites can be classified into two categories: natural satellites and artificial satellites.
The Moon as a Natural Satellite
The Moon, Earth’s only natural satellite, has sparked various theories regarding its formation.
The Earth’s natural satellite is the Moon
- An asteroid was attracted to the planet by its gravitational force. The asteroid, once attracted, began to orbit the planet and eventually took on a spherical shape.
- During the planet’s initial formation, a fragment broke off. This fragment did not move away from the planet but instead started orbiting around it.
The second hypothesis is considered to be true for the Moon. Scientists have discovered that the Moon and the Earth share the same compounds in their compositions. Consequently, they inferred that the Moon was once a part of the planet.
The Moon is the sole natural satellite of the Earth. This information is widely acknowledged now, however, in the 19th and early 20th centuries, astronomers frequently proposed the existence of other satellites orbiting the Earth.
Imaginary natural satellites of the Earth
A bolide, also known as a fireball, is a dazzling and unmistakable meteor
Frédéric Petit conducted research on bolides – particularly radiant and prominent meteors. Based on his computations, it became evident that certain bolides followed an elliptical trajectory. Consequently, he postulated that these bolides could potentially be Earth’s satellites. However, the scientific community contested his theory and highlighted the inaccuracies in his calculations, such as the lack of consideration for atmospheric drag and the failure to account for errors in the initial data.
A letter by Georg Waltemath to the Sience magazine.
(Sience) in which he states that he made a discovery.
Georg Waltemath put forward a hypothesis suggesting that the Earth is accompanied by three small satellites. According to him, these satellites have been observed by numerous scientists on various occasions, but were mistakenly identified as sunspots. Waltemath argues that satellites are generally not visible due to their low light reflection. However, he managed to calculate the exact moment when a satellite would pass through the Sun’s disk and become visible. Scientists Winkler from Jena, Germany and Ivo von Benko from Pula, Austria have confirmed his claim, although they did not observe the satellite at the expected time.
There have been other reports of sightings of Earth satellites. These reports have been made by astrologer Hornold, amateur astronomer Spiel, and scientist John Bugbee. However, none of these claims have been verified.
Quasi-satellites
Cruithne is considered a quasi-satellite, it is not classified as a natural satellite of the Earth.
In the 21st century, researchers made a fascinating discovery of celestial objects resembling satellites. These unique bodies were given the name quasi-satellites. Unlike our Moon, quasi-satellites follow an orbit around the Sun and maintain a similar distance to that of Earth. However, their orbits are not stable, resulting in periodic approaches towards our planet. In popular scientific literature, quasi-satellites are often referred to as “second moons” or “second satellites”. While this simplified terminology has led to occasional confusion, it is noteworthy that there have been articles circulating on the Internet claiming the discovery of Earth’s second natural satellite – Cruithne. In reality, Cruithne is indeed a quasi-satellite.
GLONASS is a worldwide satellite navigation system that was developed by Russia.
An artificial satellite is a spacecraft that revolves around the Earth in an elliptical orbit. Typically, this term is used to describe unmanned vehicles.
There are numerous satellites in space, including communication satellites, reconnaissance and navigation satellites, meteorological satellites, astronomical satellites, and other research satellites.
Interesting Things to Watch About Space
There are numerous captivating materials available about space that can be enjoyed, even if you have limited knowledge in this field. If you have an interest in space, Beautiful World recommends checking out the following:
- Google the Moon. You can explore the surface of the Moon and discover the landing sites of various expeditions: https://www.google.com/intl/ru/moon/
- Nasa Gallery. This website features a particularly fascinating section showcasing the photo of the day: https://www.nasa.gov/multimedia/imagegallery/iotd.html
- Nasa Instagram. On this Instagram account, you can find short videos of rocket launches, incredible photos, and videos from space: https://www.instagram.com/nasa/
- Roscosmos Instagram. This Instagram account also offers stunning photos and videos from space, including many breathtaking images of Earth: https://www.instagram.com/roscosmosofficial/
- Roscosmos TV studio offers a variety of news, popular science programs, and videos in Russian. You can find them at http://www.tvroscosmos.ru/.
P.S. This article is designed for beginners and focuses on popular science. Therefore, we have used simple language and avoided complex terminology.
Wishing you many memorable moonlit nights,
This article is written for the Beautiful World.
The Sun, known as the central star of our solar system, is orbited by all the planets in various orbits. It has an estimated age of around 5 billion years and is classified as a yellow dwarf, which means it is relatively small in size. Unlike some stars, the Sun’s thermonuclear reactions occur at a slower rate, allowing it to sustain its energy for a longer period of time. Currently, the solar system is believed to be at the midpoint of its life cycle. However, in about 5 billion years, the balance of gravitational forces will be disrupted, causing the Sun to expand in size and steadily increase in temperature. During this phase, the Sun’s thermonuclear fusion will convert all of its hydrogen into helium, resulting in the star growing to three times its current size. Eventually, the Sun will cool down and begin to shrink. At present, the Sun is primarily composed of hydrogen (90%) and a small amount of helium (10%).
At present, the Sun is orbited by a total of 8 planets, each of which is encircled by various other celestial bodies such as comets and asteroids. These objects all have their own unique orbits in which they travel. When you calculate the combined mass of all of the Sun’s satellites, it becomes evident that they are 1000 times less massive than the star itself. It is worth taking a closer look at the primary celestial bodies within this system.
Overview of the solar system
In order to understand the satellites of the Sun, it is important to familiarize oneself with the definitions: what constitutes a star, planet, satellite, and more. A star is a celestial body that emits light and energy into space, thanks to thermonuclear reactions and gravitational compression. In our solar system, there is only one star, which is the Sun. Surrounding the Sun are eight planets.
A planet is a celestial body that orbits a star and has a spherical (or nearly spherical) shape. Unlike a star, it does not emit light but rather reflects it. Additionally, a planet does not have any other large celestial bodies nearby in its orbit.
A satellite, however, refers to an entity that orbits around larger stars or planets. The gravitational force exerted by these massive celestial bodies keeps the satellite in its orbit. When considering the number of satellites that the Sun possesses, it is important to acknowledge that this roster encompasses not only planets but also asteroids, comets, and meteorites. Attempting to tally them all would be a near-impossible feat.
Planets
In the past, it was widely accepted that there are 9 planets in our solar system. However, after extensive deliberation and debate, Pluto was ultimately removed from the official list of planets. Nonetheless, it remains an integral part of our solar system.
The Sun holds the 8 major planets in their respective orbits. A celestial body can also have satellites revolving around it. There are quite large objects encountered in this system. The planets are categorized into 2 groups. The first group consists of the inner satellites of the Sun, while the second group consists of the outer satellites.
The terrestrial planets in the first group are:
- Mercury (the planet closest to the Sun).
- Venus (the planet with the highest temperature).
- Earth.
- Mars (the most accessible planet for exploration).
These planets are primarily composed of metals and silicates, and they have hard surfaces. The outer group consists of the gas giants, which include:
These planets are characterized by a high content of hydrogen and helium in their composition. They are the largest planets in the solar system.
Satellites orbiting the planets
When discussing the number of satellites that orbit the Sun, it is necessary to acknowledge the celestial objects that revolve around the planets. In ancient Greece, the planets were believed to be Venus, Mercury, the Sun, Mars, the Moon, Jupiter, and Saturn. It was only in the 16th century that Earth was added to this list. The Sun became central in people’s understanding of our solar system. Conversely, the Moon was revealed to be a satellite of Earth.
With the advancement of more sophisticated technology, it has been discovered that nearly all planets possess their own satellites. The only exceptions are Venus and Mercury, which do not have any. Presently, there are around 60 known satellites of planets, each varying in size. Among them, the smallest is Leda. This moon of Jupiter measures just 10 km in diameter.
The majority of these celestial bodies orbiting gas giants have been identified through the use of automated space technology. This has supplied scientists with imagery of these astronomical objects.
Mercury and Venus
Two relatively small celestial bodies orbiting the Sun are Mercury and Venus. Mercury, which is a satellite of the Sun, holds the distinction of being the smallest planet in our solar system. Venus, on the other hand, is slightly larger than Mercury but still lacks its own satellites.
Mercury possesses an incredibly thin atmosphere composed mainly of helium. It completes one orbit around the Sun in just 88 Earth days, while its rotation on its axis takes approximately 58 days by our standards. The temperature on the side facing the Sun can soar up to a scorching +400 degrees, whereas on the dark side it can drop down to a freezing -200 degrees.
On Venus, the atmosphere is primarily composed of hydrogen with traces of nitrogen and oxygen. This results in the presence of the greenhouse effect, causing the surface temperature to reach an extraordinary +480 degrees. Surprisingly, this is even hotter than Mercury. Venus is particularly visible from Earth due to its close proximity to our orbit.
About Earth
Our planet, Earth, holds the distinction of being the largest among all the members of the Earth group. It is truly unique in various aspects. One notable feature is the presence of a celestial body, the Moon, which is the largest satellite orbiting any of the first four planets from the Sun. The Moon is fundamentally different from other celestial bodies in terms of its atmosphere, and this distinction is what makes life possible on Earth.
Around 71% of the Earth’s surface is made up of water, while the remaining 29% consists of land. The Earth’s atmosphere primarily consists of nitrogen, along with oxygen, carbon dioxide, argon, and water vapor.
Unlike the Earth, the Moon does not have an atmosphere. It lacks wind, sound, and weather. Instead, its surface is rocky and barren, covered with craters. On Earth, meteorite impacts are gradually erased by various factors such as species, wind, and weather. However, on the Moon, these impacts remain unchanged, providing clear evidence of its past.
Mars
The Red Planet, Mars, is the fourth planet in our solar system and is known for its high iron oxide content, which gives it its distinctive red color. With a similar composition to Earth, Mars has long been a subject of interest for scientists who have wondered if it could support life. While research has not yet confirmed the existence of past or present life on Mars, it remains a fascinating celestial body. Mars has two small moons, Phobos and Deimos, which are both smaller than Earth’s Moon.
This celestial body is colder compared to our own planet. The temperature at the equator can drop to 0 degrees, while at the poles it can plummet to as low as -150 degrees. This extraterrestrial world has already become accessible for space exploration missions. It takes approximately four years for a spacecraft to reach this planet.
In ancient times, rivers used to flow across the surface of this planet. It used to have liquid water. However, presently it only has ice caps at the poles. Interestingly, these ice caps are not composed of water, but rather consist of atmospheric carbon dioxide. Scientists hypothesize that water might exist in a frozen state in the form of massive blocks beneath the planet’s surface.
The Sun is accompanied by the largest objects located behind Mars. The planets (which are satellites of the planets in this group) have been extensively studied using various techniques. The largest object in our solar system is Jupiter, which is 2.5 times more massive than all the planets orbiting the Sun combined. Jupiter is primarily composed of helium and hydrogen, similar to our star. The planet also emits heat. However, for Jupiter to be classified as a star, it would need to become 80 times more massive. Jupiter has a total of 63 satellites.
Jupiter’s neighbor, Saturn, is slightly smaller in size. Saturn is well-known for its impressive rings, which consist of icy particles with varying diameters. The density of Saturn is lower than that of water. In addition, Saturn has a total of 62 satellites.
Uranus and Neptune are situated at a greater distance compared to the preceding two planets. The aid of a telescope facilitated their discovery. These celestial bodies possess significant quantities of ice that undergo high-temperature modifications. Thus, they are commonly referred to as the “Ice Giants.” Uranus boasts a total of 23 satellites, while Neptune has 13.
Pluto
Pluto, a small celestial body, used to be considered a planet from 1930 to 2006. However, scientists have now classified it differently. According to the current planetary classification, Pluto is a prototype of a dwarf planet. Its surface is covered with frozen ice made of methane and nitrogen. Pluto has one satellite.
When studying the sun’s satellites, it is important to note that they form a complex system consisting of various objects with different characteristics and properties. Despite their differences, these objects are all bound by the force that causes them to revolve around their central star.
For centuries, scientists have been fascinated by the natural satellites of the Earth (yes, there are more than one). Throughout the 19th and first half of the 20th century, astronomers tirelessly searched for companions to the Moon. However, their assumptions and even convincing evidence were repeatedly proven wrong. Nowadays, it is common knowledge that the Moon is the only natural satellite of the Earth. Nevertheless, there are numerous other candidates that continue to pique the interest of astronomers, as they are not fictional, but actual objects that were mistakenly labeled as permanent satellites of our planet.
Bolide
Frederic Petit, a prominent French astronomer, is well-known among enthusiasts of celestial bodies. He served as the director of the Toulouse Observatory during the mid-19th century. Today, Petit is primarily recognized for his support of the theory that the Earth has multiple natural satellites, rather than just the Moon. According to Petit, these satellites are bolides, which are large and brilliantly illuminated meteors. The astronomer believed that these candidate satellites revolved around the Earth in an elliptical orbit. One of the most famous bolides observed by Petit occurred in 1846. After analyzing his own observations and data from other scientists, Petit concluded that this celestial body had a rotation period of 2 hours and 45 minutes. Its perigee measured 11.4 km, while its apogee reached 3570 km.
Even though some astronomers confirmed Frederick Petit’s measurements and calculations, it didn’t take long for his assumption to be proven false. In 1851, Urbain Leverrier presented evidence that disproved the theory of the Toulouse scientist.
New hypotheses
Petit wasn’t the only astronomer attempting to challenge the accepted understanding of the number of natural satellites orbiting Earth. He had a partner in this pursuit, Dr. Georg Waltemath, a scientist from Hamburg. In 1898, Waltemath announced the discovery of a system of small satellites. According to his calculations, one of these satellites was situated slightly over a million kilometers from Earth and completed one revolution in 119 days. The hypothetical satellite had a diameter of 700 kilometers.
Waltemath had predicted that the second moon would pass in front of the sun in February 1898, and this event would prove his theory correct. Amateur astronomers in Germany did indeed observe the satellite. However, none of the professional astronomers who were observing the sun that day noticed anything similar.
Another attempt
Undeterred, Waltemath continued his search. In July of the same year, he published an article about another potential candidate for the role of Earth’s second moon. According to his calculations, this space object had a diameter of 746 km and orbited at a distance slightly greater than 400,000 kilometers from our planet. However, these findings were also not confirmed. The hypothetical natural satellites proposed by Waltemath failed to gain the status of actual objects.
Mysticism
The peculiarity of the satellite “discovered” by Waltemath was its exclusive visibility during its passage through the Sun’s disk. This object had minimal light reflection, making it extremely difficult to observe. In 1918, astrologer Walter Hornold brought attention to the reemergence of the Waltemath satellite. He confirmed its “dark” characteristics and gave it the name Lilith, which coincided with the first wife of Adam according to the Kabbalah. The astrologer argued that this second moon was comparable in mass to the existing one.
These statements generated amusement within the scientific community. The presence of such a massive celestial body would not have gone unnoticed, as it would have significantly influenced the Moon and impacted its movement.
Political Matters
The Moon, Earth’s natural satellite, as well as Mars and Venus, its closest neighboring planets, have always intrigued people with their mysteries. Throughout the last century, these celestial bodies have been linked to speculations of hosting extraterrestrial civilizations or serving as military bases for hostile nations. Given these prevailing beliefs, the notion of covertly launching artificial satellites into orbit gained traction as a more plausible hypothesis.
In the early days of the space age, in the mid-20th century, there were murmurs about a pair of such entities. Eventually, the press started to speculate about their celestial origins. The buzz surrounding these novel satellites died down in 1959, when renowned astronomer Clyde Tombaugh (the very same scientist who famously discovered Pluto) declared, after extensive research of the Earth’s vicinity, that there were no objects of greater luminosity than stars with a magnitude of 12-14.
Surveillance of the space near Earth
In modern times, there are few individuals who are unfamiliar with the name of our planet’s natural satellite. The Moon is now universally acknowledged as the one and only. Nevertheless, astronomers are continuously monitoring the outer expanse surrounding our planet. The objective of such investigations is not to uncover new satellites, but rather to safeguard against potential collisions, anticipate them, and ensure the security of station operations. Clyde Tombaugh was among the pioneers in undertaking such an exploration.
Currently, the pursuit of celestial bodies in the vicinity of Earth is the objective of several significant endeavors concurrently. Thus far, no new natural satellites of Earth have been discovered during the course of these investigations.
Quasi-satellites
Undoubtedly, the Moon is not the sole entity existing near our planet. Recent studies have revealed a wealth of comparable data. There are asteroids that exhibit a 1:1 orbital resonance with Earth. These celestial bodies are often referred to as “second moons” in the media and popular scientific literature. Nevertheless, the key distinction lies in the fact that these objects do not orbit Earth, but rather orbit the Sun.
An excellent illustration of a celestial entity of this nature is asteroid (3753) Cruithne. It intersects the paths of Earth, Venus, and Mars during its trajectory. The orbital path of the asteroid is considerably elongated, but regrettably, it never approaches our planet closely enough to be detected with inferior instruments. Cruithne can only be observed using a telescope of considerable power.
Trojans
Trojans, also known as Trojan horses, are a type of malicious software that disguises itself as a legitimate program or file. They are named after the Trojan Horse from Greek mythology, which was used by the Greeks to gain access to the city of Troy.
Trojans are often spread through email attachments, downloads from untrusted websites, or by exploiting vulnerabilities in software. Once installed on a computer, they can perform a variety of malicious actions, such as stealing sensitive information, damaging files, or giving remote control of the infected computer to a hacker.
To protect against Trojans, it is important to use reliable antivirus software, keep software and operating systems up to date, and exercise caution when opening email attachments or downloading files from the internet. Regularly backing up important files can also help mitigate the damage caused by a Trojan infection.
In conclusion, Trojans are a serious threat to computer security and can cause significant harm if not properly guarded against. Taking proactive measures to protect against these malicious programs is essential for maintaining the integrity and security of personal and business systems.
There is a separate group of objects that are occasionally classified as Earth’s natural satellites, although they are not. These objects are known as Trojans – asteroids that move in the same orbit as our planet, either ahead of it or behind it. Currently, only one such object has been confirmed – asteroid 2010 TK7. This asteroid is positioned 60 degrees ahead of Earth. With a diameter of 300 meters, 2010 TK7 is relatively small and not very bright. Its discovery has sparked increased interest among scientists in the search for Trojans near Earth.
Optical phenomenon
Sometimes, but rarely, the question arises about how many natural satellites the Earth has just by looking at the night sky. Under certain conditions, when several factors are present, it is possible to observe a phenomenon known as a false moon. In order for this to occur, the full or almost full moon must be bright enough. A halo will appear around it and lunar rays will be refracted in ice crystals of layered clouds, creating bright luminous dots on both sides of the moon. An inexperienced observer may momentarily believe that there are new space objects where the Earth’s natural satellite (the Moon) or Mars and other planets traverse space. However, this illusion is quickly dispelled. A false moon, or parselena, is more of an optical illusion than an actual celestial body.
Dual system
The concept of a dual system refers to a system that operates on two different levels or has two distinct components. This dualism can be observed in various fields, such as technology, psychology, and philosophy.
In technology, a dual system can refer to a computer architecture that combines two different types of processors, such as a central processing unit (CPU) and a graphics processing unit (GPU). This allows for more efficient and specialized processing, as each component can handle different types of tasks.
In psychology, a dual system can refer to theories that propose that the human mind is composed of two separate systems or processes. For example, the dual-process theory suggests that there are two modes of thinking: one intuitive and automatic, and the other reflective and deliberative.
In philosophy, the concept of a dual system can refer to dualistic theories that posit the existence of two fundamental and irreducible entities or substances. For instance, in Cartesian dualism, the mind and body are considered to be separate and distinct entities.
Overall, the concept of a dual system is a versatile and widely applicable idea that can be found in various disciplines. It allows for a deeper understanding of complex phenomena and provides a framework for analyzing and explaining different aspects of reality.
The Moon, being the nearest celestial body to Earth, is constantly the focus of numerous scientific investigations. Naturally, not everything about it is fully understood. There is still ongoing debate, for instance, regarding its origin theory. Nevertheless, it can confidently be regarded as one of the most extensively researched entities in space, serving as a symbol and distinguishing characteristic of our abode in the vast Universe. This latter fact is aptly exemplified by one of the designs of our planet’s flag, which prominently features the Earth’s natural satellite.
Interestingly, recent research has shown that the status of the Moon is not as clear-cut as previously thought. Astronomers now believe that the Earth’s natural satellite and our cosmic home are actually a double planet, as they both revolve around a single center of mass. This center of mass is not located at the center of the Earth, but rather about 5 thousand kilometers away from it. The substantial size of the Moon, in comparison to other satellites, also supports this hypothesis. A similar system can be seen in the case of Pluto and Charon, which both revolve around the same center of mass and always have the same side facing each other.
