Betelgeuse is a reddish bright star in the constellation Orion. It was abnormally fading in late 2019 and early 2020. After in-depth study, astronomers published a latest research paper and several images taken by the Very Large Telescope of the European Southern Observatory last week, revealing the brightness variations of Betelgeuse clearly.

On the far left was the image of Betelgeuse taken in January 2019, showing the normal brightness of the star. The remaining three images were taken in December 2019, January 2020 and March 2020 respectively. The brightness variations in the southern hemisphere of Betelgeuse can be seen.

Astronomers suggest that Betelgeuse ejected a large gas bubble. As its surface region cooled down after, the temperature of the ejected gas decreased in space and a dark solid dust veil was formed by condensation that blocked a portion of light from the southern hemisphere of the star, causing to the "Great Dimming" that lasted for few months.