Planets of the Solar System
What is a solar system?
A solar system is a planetary system that links a set of astronomical objects under the effect of gravity. Planetary systems are made up of one or more central stars and different objects orbiting around them. In the case of our solar system, the central star is the Sun.
What does our solar system consist of?
Our solar system has 8 planets, 5 dwarf planets, and a vast number of minor bodies.
What is a planet?
A planet is a celestial object without its own light that orbits a star and has sufficient mass to give it a spherical shape due to its own gravity. The International Astronomical Union has distinguished planets from dwarf planets by defining the latter as not managing to clear their orbit; that is, they share it with other significant objects, such as asteroids, comets, and other small bodies.
The classification of planets or dwarf planets has nothing to do with their intrinsic nature, relevance, or interest from a scientific point of view.
What planets are in the solar system?
The planets of the solar system are (in order of proximity to the Sun): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Pluto, which was previously considered a planet, is now one of the 5 dwarf planets recognized in the solar system, along with Ceres, Haumea, Makemake, and Eris.
What is Mercury like?
Mercury is a rocky planet with a lot of craters. Gravity on Mercury is 3.7 m/s2; that is, objects weigh 62% less than on Earth.
Mercury is the planet closest to the Sun and is slightly larger than the Earth’s Moon, which makes it the smallest of the 8 planets in the solar system. It has no satellites.
Despite its proximity to the Sun, it’s not the hottest planet of all because it has practically no atmosphere. It is even thought that there could be very deep, dark craters with ice near its poles. Mercury rotates at high speed around the Sun, taking only 88 Earth days to complete each turn; however, its rotation is much slower than that of Earth. Mercury rotates on its own axis just 1.5 times for every time it circles the Sun. During the day, its temperatures reach 430°C, but at night, they drop to -185°C. It doesn’t have seasons since its axis of inclination is barely 2º.
What is Venus like?
The diameter of Venus is 12,104 kilometers. It is very similar in size to Earth, and it is also a rocky planet with a core made of iron and hot rock.
Its atmosphere and temperature, on the other hand, are quite different from Earth. Venus is the hottest planet in the solar system. The atmospheric pressure of Venus is 90 times higher than on Earth. Its temperature reaches 463.85°C. This is due to the extreme greenhouse effect caused by carbon dioxide and sulfuric acid clouds that make up its dense atmosphere.
On Venus, the Sun rises in the west because it spins in the opposite direction than the other planets in the solar system. Venus takes 243 Earth days to rotate on its own axis and 225 days to revolve around the Sun.
What is Earth like?
Earth is the third planet from the Sun. It is a sphere that’s flattened at the poles; therefore, its equatorial diameter (12,756 km) is 43 km wider than its polar diameter. The atmosphere on Earth is 99% oxygen (20.95%) and nitrogen (78.08%). It has a large amount of water in its liquid state.
The atmospheric temperature ranges from -89.15°C to 56.7°C, with an average of 14.05°C. It is the largest rocky planet in the solar system. Earth has one satellite, the Moon, which exerts a great influence on the tides and the seasons.
The most abundant elements on the planet are oxygen, silicon, aluminum, and iron. Its composition, magnetic field, position, and orbit bring together a conglomerate of difficult conditions that have made the appearance, maintenance, and evolution of living beings possible from the early moments of its formation; it is the only planet with evidence of life.
What is Mars like?
Mars is about half the size of Earth in terms of diameter, which makes it the second smallest planet in the solar system after Mercury. It is known as the “Red Planet” because of its reddish appearance. This is due to the abundance of iron oxide on its surface.
The atmosphere on Mars is primarily composed of carbon dioxide, and it is much thinner than Earth’s. Its climate is extreme, with temperatures that can range from -140ºC to 20ºC, and large dust storms can cover the entire planet for months. Its days last 25 hours, and it takes 1.88 years to revolve around the sun. The gravity on Mars is 62% lower than on Earth. It has two irregular moons: Phobos and Deimos.
Mars is the only planet in the solar system besides Earth where evidence of liquid water has been found. It is also thought that there is frozen water at the poles of the planet and under its surface.
Space missions have proven that Mars once had a warmer climate. This, along with the presence of other elements such as carbon, nitrogen, and phosphorus, could have offered suitable conditions for life in the past. Similarly, organic molecules have been discovered, suggesting that it was – or is still – home to microscopic life forms.
What is Jupiter like?
Jupiter is 11 times bigger than Earth. It has a diameter of 139,822 km. However, it is not a rocky planet, consisting mainly of gases and fluids like hydrogen and helium. Its atmosphere is very turbulent, and it has different bands of colored clouds, such as the Great Red Spot, which is a giant storm that has been active for at least 400 years.
Jupiter has 79 recognized moons, although it could have more. These include the four Galilean moons, which are all very different from each other and which have characteristics that are of significant interest to the scientific community. There is even speculation about the possibility of life in the subsurface ocean spreading out under the ice sheet on its surface.
Days on Jupiter last only 10 hours, and the planet takes 11.86 Earth years to complete one lap around the sun. Jupiter’s magnetic field is 20,000 times stronger than Earth’s, making it the most powerful of all the planets in the solar system. Its gravity is 2.5 times stronger than Earth’s.
What is Saturn like?
Saturn is also a gaseous planet like Jupiter. It is the second largest in the solar system. It has colorful rings that are composed mainly of ice and rock. It is the only planet in the system with this feature.
Saturn’s atmosphere is composed of hydrogen (96%) and helium (3%), with small amounts of other gases like methane and ammonia. It has cloud patterns, including dark bands and areas, as well as a large white spot at the south pole. On Saturn, there are more than 80 known moons orbiting around it, including Enceladus, which has geysers spouting water and other materials, and the largest moon in the solar system, Titan. It takes Saturn 29.46 Earth years to go around the Sun.
What is Uranus like?
Uranus is mainly composed of ice, ammonia, and methane. Its average temperature is -205.2ºC. Its atmosphere is primarily made of hydrogen and helium, in addition to small amounts of methane. It has an extremely long, slow orbit, taking 84 Earth years to complete one orbit around the sun. This has confused astronomers about whether it was a planet or not.
Uranus’s axis of rotation is quite unusual with respect to the rest of the planets in the solar system: it is almost at a right angle to the plane of its orbit. This means that its poles are pointing toward the Sun instead of its equator, which makes for extreme seasons and complex atmospheric dynamics.
What is Neptune like?
Neptune is the planet farthest from the Sun. It takes 165 Earth years to complete its very long orbit. It is an icy planet with an approximate diameter of 49,500 km. It is mainly composed of hydrogen and helium, with small amounts of methane and ammonia in its atmosphere, which is quite active.
It has the fastest winds in the solar system, which reach speeds of up to 2,000 km/h. The temperature in the upper part of its atmosphere is very cold, around -218°C. Neptune has a weak ring system, just like Uranus. One day on Neptune lasts 16 hours. It has 14 known moons.
What other elements are there in the solar system?
In addition to the planets, asteroids, comets, meteoroids, satellites, and many other elements in interplanetary space can be found in the solar system.