|
The image of the Andromeda Galaxy seen from the Sahara Desert was published on the 11th of ‘Today’s Astrophotography’ (APOD), attracting the attention of space enthusiasts. Because this galaxy tells us one important fact.
What is the furthest distance we can see with the naked eye? Don’t be surprised. It can be seen 250 million light-years away. The proof is the Andromeda galaxy in the night sky. The light from the Andromeda Galaxy that reached your retina tonight is the light that left it 2.5 million years ago. It also means that you are looking at an object from the most distant past. In the universe, space is time.
Most of the stars, clusters, and nebulae that we can see in the night sky are within our Milky Way, and the distance is regarding a few hundred or several thousand light years. So, what you see tonight is actually what they looked like hundreds of years ago or thousands of years ago. This is because light travels at a speed of 300,000 km/s.
If the speed of light were infinite, things from the universe would pour into our eyes at the same time and we would lose consciousness. It is fortunate that the speed of light is finite. Anyway, the farthest we can see with the unaided eye is the Andromeda Galaxy, and the image above is a close-up of the galaxy, also known as M31, taken last month in Morocco’s Sahara Desert.
The image above is a combination of 3 backgrounds and 1 foreground exposure. All were taken with the same camera, in the same place, on the same day, and the foreground image was taken at dusk in the evening. Just above the central core of the Andromeda Galaxy that dominates the center of the image, the bright bundle of light visible is M31’s satellite galaxy M110. It’s wonderful to see our Milky Way’s neighboring galaxies with your own eyes, but prolonged camera exposures can capture many breathtaking details.
The Andromeda Galaxy is a massive spiral galaxy with a diameter of 200,000 light-years, regarding twice that of our Milky Way, and contains regarding 1 trillion stars. According to recent data, the Milky Way will collide and merge with the Andromeda Galaxy in regarding 4 billion years. Impatient astronomers have already named the merged galaxy. It’s called ‘milcomeda’.
Kwang-Sik Lee, Science Columnist [email protected]