Sagittarius A facts for kids
Sagittarius A (or Sgr A) is a very special area at the very center of our Milky Way galaxy. It's like a giant radio signal coming from that spot! You can find it in the Sagittarius part of the sky, but we can't see it directly with our eyes. That's because huge clouds of cosmic dust in our galaxy's spiral arms block the view.
Sagittarius A is actually made up of three main parts:
- Sagittarius A East: This is what's left after a huge star exploded (a supernova).
- Sagittarius A West: This looks like a spiral shape made of gas and dust.
- Sagittarius A*: This is a very bright, small radio source right at the center of the spiral. It's believed to be a giant supermassive black hole.
These three parts are all connected. Sagittarius A East is the biggest. Sagittarius A West is inside East, and Sagittarius A* is right in the middle of West.
Sagittarius A East
This part of Sagittarius A is about 25 light-years wide. A light-year is how far light travels in one year, so 25 light-years is a huge distance! Scientists think it's the leftover cloud from a star that exploded a long, long time ago, maybe between 35,000 and 100,000 years ago.
However, it would have taken a lot more energy than a normal star explosion to create something this big. Some scientists believe that Sagittarius A East might be what's left of a star that exploded because it got too close to the giant black hole at the center of our galaxy. The black hole's strong gravity might have squashed it, causing the huge explosion.
Sagittarius A West
From Earth, Sagittarius A West looks like a spiral with three arms. But it's actually made of several clouds of dust and gas. These clouds are constantly moving around and falling towards Sagittarius A*. They move incredibly fast, sometimes as quickly as 1,000 kilometers (about 620 miles) every second!
The outer layer of these clouds is "ionized." This means the gas particles have an electric charge. This charge comes from many huge, bright stars that are also found in the central part of our galaxy. Scientists have found over a hundred of these massive stars so far.
Sagittarius A*
Sagittarius A* (often shortened to Sgr A*) is the most exciting part of Sagittarius A. Scientists are almost certain that a supermassive black hole is located right here, at the very center of our galaxy.
Powerful telescopes like the Very Large Telescope and the Keck Telescope have watched stars orbiting around Sgr A*. These stars move faster than any other stars in our galaxy! One star, called S2, gets incredibly close to Sgr A*. When it's closest, it moves at speeds over 5,000 kilometers (about 3,100 miles) per second!
Scientists were excited about a gas cloud that was expected to crash into the black hole around 2014. This event was hoped to give them even more information about this mysterious black hole.
