Astronomy Picture of the Day
    


APOD: 2023 March 22 M31: The Andromeda Galaxy
<< Yesterday 22.03.2023 Tomorrow >>
APOD: 2023 March 22  M31: The Andromeda Galaxy
Credit & Copyright: Abdullah Al-Harbi
Explanation: How far can you see? The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy, over two million light-years away. Without a telescope, even this immense spiral galaxy appears as an unremarkable, faint, nebulous cloud in the constellation Andromeda. But a bright white nucleus, dark winding dust lanes, luminous blue spiral arms, and bright red emission nebulas are recorded in this stunning fifteen-hour telescopic digital mosaic of our closest major galactic neighbor. But how do we know this spiral nebula is really so far away? This question was central to the famous Shapley-Curtis debate of 1920. M31's great distance was determined in the 1920s by observations that resolved individual stars that changed their brightness in a way that gave up their true distance. The result proved that Andromeda is just like our Milky Way Galaxy -- a conclusion making the rest of the universe much more vast than had ever been previously imagined.

January
February
March
April
May
June
July
August
September
 < March 2023  >
Mo Tu We Th Fr Sa Su


12345
6789101112
13141516171819
20212223242526
2728293031

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Based on Astronomy Picture Of the Day

Publications with keywords: Andromeda galaxy - M 31
Publications with words: Andromeda galaxy - M 31
See also:
All publications on this topic >>