The Andromeda Galaxy from Rio

The Andromeda Galaxy (M31) is the Milky Way's largest neighbor and the most distant object visible to the naked eye, located 2.5 million light-years from Earth. Classified as a giant spiral, it hosts approximately one trillion stars across a 220,000 light-year diameter. Its core is composed of ancient stars, while its arms reveal regions of intense star formation. M31 is currently approaching us at 110 km/s, on a trajectory that will lead to a galactic merger in 4 billion years. These images are the result of a 3-hour exposure using a Seestar S50 telescope on 12/21/2025, with the galaxy at an average altitude of only 18° above Rio's horizon.

Seestar S50 telescope

Total integrated exposure time was 3 hours approximately (1,080 10-sec subframes stacked). He "denoise option" of the telescope was used to remove noise. The maximum and mean altitude of the galaxy were: 25° and 18°, only.