Our galaxy, the Milky Way, and its neighbor twice its size, Andromeda, are on a collision course. Both are approaching each other at a speed of 113 kilometers per second due to gravitational pull, and although they are expected to collide in 4.5 billion years, their outer layers have already begun to merge .
Meanwhile, people on Earth have the opportunity to observe Andromeda, also known as Messier 31 , with the naked eye.
From mid-August to November, the spiral galaxy appears in the night sky of both hemispheres of our planet. Despite being located 2.5 million light-years away, Andromeda occupies a quarter of a degree in the sky. This is equal to half the width of a full moon, according to NASA.
When will the Andromeda galaxy be visible?
Due to its remoteness, Andromeda has a diffuse glow. Therefore, to capture it with the naked eye, it is not enough to have a clear sky, but also that there is an absence of lunar brightness and little light on the surface.
For this reason, although the galaxy already appears in the sky on these dates, it is best to observe it on nights close to the new moon phase. In August, this stage will arrive in the last week of the month ( from August 24 to 31 ). Likewise, a place with little light pollution should be sought, such as outside cities or in rural areas.
Location of Andromeda in the Peruvian sky at 3 am on August 24. Image: Stellarium / The Republic
How to locate Andromeda in the sky?
The galaxy appears above the horizon, heading northeast , around midnight in Peru and other countries in the southern hemisphere (Argentina, Chile, etc.), and hours earlier in the northern hemisphere (Mexico, Spain, etc.).
It is located next to the Andromeda constellation —hence its name—, just at the height of the character’s ‘belt’. Meanwhile, the Pegasus constellation, characterized by having a quadrilateral formed by its stars, can serve as a guide to locate the galaxy.
The star Mirach can also help locate the Andromeda galaxy. Image: Stellarium / The Republic
The best time to see Andromeda is between 2:00 am and 3:00 am , when it is located in the north, at a higher point in the sky.
To the naked eye it will look like a small cloud with some detail, but if you use binoculars, you can clearly see the majesty of this neighboring galaxy.
Location of the Andromeda galaxy (no illustration of the constellations). Image: Stellarium / The Republic
Andromeda has an apparent magnitude of 3.5 (the lower the number, the brighter), which makes it more conspicuous than most visible stars (magnitudes 4 to 6), but less conspicuous than naked-eye planets . (magnitudes from 1 to less than 0).
For this reason, astronomical observation experts recommend that anyone who decides to venture in search of Andromeda or any other deep space object should first try to accustom their eyes to the darkness of the sky.
