Where do you live? That’s a common question and the common answer is such-and-such Street. We may live apart in terms of street, city, and even nation, but we all have a common address, the Solar System!
How did the solar system come into existence? It is generally believed that it emerged from a gaseous cloud several billion years ago and planets, an important component of the system, were formed out of this gaseous cloud and its dust.
Till last year we all knew that there were nine planets in the Solar System, but now Pluto is officially an outcast! This is because Pluto does not fit the International Astronomical Union’s (IAU) definition of a planet. It is now a dwarf planet.
The chief member of our solar system is the Sun, and its keeps planets in order by its gravitational pull. The Sun is a bright star and exudes heat and light through nuclear fusion. Apart from the Sun, our solar system contains planets, natural satellites, dwarf planets, and small solar system bodies.
A planet, according to the IAU, is a spherical object that orbits the Sun. It must have no small objects near it. Today, there are eight recognized planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Mercury and Venus have no natural satellite unlike the other six. The Earth’s natural satellite is the Moon.
Mercury, Venus, Earth, Mars are known as the inner planets, while Jupiter, Saturn, Uranus, and Neptune are the outer planets. The former are rocky, have minerals and metals, have few or no natural satellites, and don’t have rings. The latter are known as gas giants and have rings.
Dwarf planets are also spherical objects orbiting the Sun, but unlike planets their surroundings don’t have to be clear of smaller celestial bodies. Pluto, Ceres, and Eris are the dwarf planets in the solar system.
Small solar system bodies include asteroids and comets. Trans-Neptunian objects and other small celestial objects also come under this category. Asteroids are mainly found in the region between Mars and Jupiter. They are rocky objects that could span several hundred kilometers or be small like dust. Ceres is the largest asteroid. Comets are mainly made of ice, and when they come near the Sun this ice melts to form a comma like shape. Comets that have orbits less than 200 years, such as, Halley’s Comet are known as short-period comets, while those with orbits spanning thousands of years are known as long period comets. Small solar system bodies that lie in the region beyond Neptune are known as Trans-Neptunian objects.
Technological advances in the form of telescope and spacecraft have helped scientists to obtain a lot of information about the solar system. It’s not a static situation out there, and as new technologies develop here, new and exciting facts about the solar system are uncovered. And you are wrong if you thought only astronomers and scientists looked through the telescope, it’s a hobby for thousands of people!
Tania Penwell is a regular contributor to Infinite Universe - a blog where young and old alike can learn about the solar system, science, and the wonders of the universe. |
