Understanding the Solar System: Planets, Theories, and Formation
Understanding the Solar System
Planets: Mercury and Mars
Choose two of the following planets:
Mercury is the closest planet to the Sun, receiving 10 times more solar energy than Earth. During the day, extreme temperatures are reached, while nighttime temperatures are similar to those on the Moon. Mercury is notable for being the smallest planet with the smallest mass. Its orbital speed is the greatest, resulting in a shorter year. Its density is the largest in the solar system. The Mariner 10 probe found that Mercury has a magnetic field and an extremely tenuous atmosphere. Craters on Mercury are similar to those of the Moon, and glaciers have been discovered in areas where sunlight doesn’t reach.
The Viking space mission unveiled differences in Mars’ hemispheres. The southern hemisphere is rather uneven, while the northern hemisphere is smooth, covered in plains. Analysis reveals sandy materials similar to volcanic rock due to their high iron content. Water ice varies seasonally, and dry ice snow is present. The surface is full of rocks. Mars has two moons, Phobos and Deimos, discovered by A. Hall in 1877.
Solar System Composition
The solar system is formed by the Sun, 8 planets, and 3 dwarf planets, more than 30 satellites, thousands of asteroids, and a large number of comets and meteorites. Except for Mercury and Pluto, all the planets orbit the Sun. Uranus and Venus rotate on their axes. To calculate the distance of planets, there is a law called the Titius-Bode Law (Rn = 0.4 + 0.3 * 2^(n-1)). This law suggests that there is another planet between Mars and Jupiter.
Planet Classification
The planets are classified as:
- Inner Planets: Mercury, Venus, Earth, Mars (small and dense)
- Outer Planets: Jupiter, Uranus, Saturn, Neptune (gas giants)
- Dwarf Planets: Eris, Ceres, Pluto
The Sun
Write what you know about the Sun: The Sun is the nearest star to Earth, and its energy has allowed life to flourish. The mass of the Sun is 300,000 times that of Earth, and its temperature is 6000 °C. Sunspots are activated by disturbances on Earth, thanks to the aurora borealis. The spots change position as the Sun rotates on its own.
Theories of the Universe and Solar System
Inflationary Theory
The Inflationary Theory assumes that a single force split into four, producing the origin of the universe, and it continues to grow (Alan Guth).
Steady State Theory
The Steady State Theory, proposed by Edward Milne, states that the universe has no origin and no end, since interstellar matter has always existed. Secondly, it argues that the general appearance of the universe is identical in space and time.
Big Bang Theory
The Big Bang Theory posits that the universe’s matter had been concentrated in a small point, the cosmic egg. The explosion is known as the Big Bang, marking time zero. Then, a string would produce photons, atoms, resulting in the formation of protogalaxies, which seven hundred years later would form into galaxies.
Solar System Formation Theories
Catastrophic Theory
The Catastrophic Theory suggests that a star flew past the Sun and caused movement of gaseous materials, with protuberances emerging that later joined, leading to the formation of the planets.
Nebular Theory
The Nebular Theory proposes that from dust and gas, the pressure of starlight would form a nebula and a heavier nucleus. By contracting, the core would become a star, the Sun. As the temperature exceeded a certain point, the shreds would contract, giving rise to the planets.