By: Dian P Triani
GALAXY The Milky Way is home to Solar system our. Sunas star The parent Solar System has gravity strong enough to bind the eight known planets, and other small bodies such as planetoids, asteroids, meteoroids, and comets.
Based on their distance from the Sun, the eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Although it looks large and is the main source of energy for Earth, the Sun is actually a fairly common star found in the Milky Way. It looks big because it is closest to Earth.
Of Milkyway Galaxy alone there are about 100 billion stars! Many of these stars are much larger in size and energy than the Sun. The position of the Sun is not at the center of the Milky Way galaxy, but in one of its spiral arms.
Position of the Sun in the Milky Way
Star-stars other than the Sun in the Milky Way galaxy also have many planetary systems such as solar system. However, because these stars are very far from us, not all of them can be detected from Earth.
So far, there are more than 4,000 confirmed extrasolar planets in the Milky Way. These planets are known as exoplanets.
Our nearest neighbor, Proxima Centauri, is probably surrounded by three planets (the planets proxima b, c and d). Proxima b is about the same size as Earth and orbits Proxima Centauri once every 11 days.
Based on the distance between Proxima b and its star, the planet is in a zone that allows liquid water to exist, known as the “habitable zone”. However, astronomers are still observing the planets Proxima c and d to confirm their existence.
Although Proxima Centauri is the closest star to Sunbut the distance is still very far when calculated in units that we know on Earth, which is 4.2 light years or 39 trillion kilometers!
The diameter of the Milky Way galaxy itself is much larger than that, which is about 100,000 light years. Therefore, to detect planetary systems outside the solar system, various techniques with high precision are needed. Astronomers in various countries are currently still developing various detection methods, so the search for exoplanets is still an active research subject.
A galaxy is a system of billions of stars that are bound by gravity and revolve around their center. The time it takes for the Sun and the Solar System to complete one cycle around the Milky Way is about 225-250 million years. This period is also known as a galactic year.
So what is in the center of the Milky Way? Is a black hole with a very large mass (supermassive black hole) known as Sagittarius A*.
A black hole is a celestial body whose gravity is so great that nothing can escape its gravitational pull, including light. No kidding, the mass of Sagittarius A* is about four million times the mass of the sun. Because the gravity of this Sagittarius A* black hole is so great, it is able to pull the 100 billion stars in the Milky Way around it.
Around the center of the galaxy, there is a thick lump, otherwise known as a “bulge”, which is made up of stars, dust and gas that are more densely packed. It is beyond this bulge that the stars inhabit the thinner spiral arms, including the sun.
Dian P Triani
Astrophysics Researcher, Australian National University
This article was published on Kompas.com thanks to the collaboration with The Conversation Indonesia. The above article is taken from the original article entitled “Curious Kids: what is the center of the Milky Way galaxy?“. The contents are beyond the responsibility of Kompas.com.
Get updates news of choice and breaking news every day from Kompas.com. Let’s join the Telegram group “Kompas.com News Update”, how to click the link https://t.me/kompascomupdate, then join. You must first install the Telegram application on your cellphone.