Milky Way Galaxy Overview Quiz

Milky Way Galaxy Overview

• Barred spiral galaxy approximately 13.6 billion years old.
• Diameter of the galaxy's disk is around 100,000 light-years, with a thickness of about 1,000 light-years.

Solar System Dynamics

• Solar system orbits the Milky Way's center at a speed of approximately 515,000 mph (828,000 km/h).
• Takes roughly 250 million years for a complete revolution around the galaxy, with the last position coinciding with early dinosaur emergence.

Galactic Location

• Our solar system resides in the Orion-Cygnus Arm, located 25,000 to 30,000 light-years from the Milky Way's center.
• Nearby galactic arms include Perseus, Carina-Sagittarius, Scutum-Centaurus, and Norma.

Sagittarius A* and Galactic Center

• Supermassive black hole at the galaxy's core is known as Sagittarius A*, with a mass four million times that of the Sun.
• First image of Sagittarius A* captured in 2022 using innovative techniques to visualize its shadow.

Naming of the Milky Way

• Named for its milky white appearance in the night sky, derived from Greek mythology involving the goddess Hera.
• Known as "Silver River" in China and "Backbone of Night" in the Kalahari Desert.

Astronomical Advancements and Research

• The European Space Agency's Gaia mission, launched in 2013, significantly enhanced our understanding of the Milky Way’s structure and size.
• Early studies likened reconstructing the Milky Way to describing a forest from within it due to observational challenges.

Historical Contributions

• Jan Oort, a pivotal figure in understanding the Milky Way, calculated stars' orbital speeds and recognized the galaxy's rotation.
• The Oort Cloud, a distant repository of comets, is named in his honor.

Structure of the Milky Way

• The center features a peanut-shaped galactic bulge, approximately 10,000 light-years across, containing about 10 billion stars, mainly old red giants.
• The total star count in the Milky Way is around 200 billion, with stars in the bulge representing significant early galaxy evolution.

Observational Challenges

• Telescopes developed since the 1990s have facilitated the cataloging of stars and determining their distances from Earth, aiding in galaxy structure research.