Andromeda galaxy

Definition

The Andromeda Galaxy is a spiral galaxy approximately 2.537 million light-years from Earth. It is the nearest spiral galaxy to the Milky Way and on a collision course with it.

5 Must Know Facts For Your Next Test

1. The Andromeda Galaxy, also known as M31, is the largest galaxy in the Local Group, which also contains the Milky Way and about 54 other galaxies.
2. It has an estimated diameter of about 220,000 light-years, making it over twice the size of the Milky Way.
3. Andromeda and the Milky Way are expected to collide in about 4.5 billion years due to their mutual gravitational attraction.
4. The mass of the Andromeda Galaxy is estimated to be around $1.23 \times 10^{12}$ solar masses.
5. Newton's Law of Universal Gravitation can be used to estimate the force of attraction between Andromeda and other galaxies in its vicinity.

Review Questions

• What is the approximate distance of the Andromeda Galaxy from Earth?
• How does Newton's Law of Universal Gravitation apply to the future collision between Andromeda and the Milky Way?
• Estimate the mass of Andromeda in terms of solar masses.

Related terms

Newton's Law of Universal Gravitation:

$F = G \frac{m_1 m_2}{r^2}$, where $F$ is the gravitational force between two masses ($m_1$ and $m_2$), $r$ is the distance between their centers, and $G$ is the gravitational constant.

Local Group: A group of more than 50 galaxies that includes both our Milky Way galaxy and Andromeda.

Light-year: A unit of astronomical distance equivalent to about 9.46 trillion kilometers (5.88 trillion miles), representing how far light travels in one year.