The Size of Our Milky Way:
The diameter of the Milky Way galaxy is estimated to be between 100'000 and 200'000 light-years. This range varies because measuring the galaxy's exact boundaries is challenging due to its faint outer regions and the presence of a dark matter halo that extends beyond the visible disk.
However, newer studies have revealed that the Milky Way's structure, including its stellar halo, extends farther, possibly reaching or exceeding 200,000 light-years when the outer edges are included.
In 2019, EHT published the first image of the SMBH at the center of M87 galaxy using (low energy with long wavelength) radio light waves by combining multiple telescopes around our planet using a technique called radio interferometry. This SMBH is 6,5 billion times the mass of our sun and is situated 55 million light-years away from us.
In 2022, EHT published a second image of Sagitarius A* the black hole at the center of our milky way galaxy. This SMBH is 4 million times the mass of our sun and is located around 27'000 light years away from us. Its event horizon which is sphere at the heart of a black hole has a diameter the size of Mercury's orbit around the sun approximately 160 million km.
