Deep-sky objects may appear static throughout our lives, but by carefully “flashing” between archive and current images, we can notice real changes in their appearance.

Amateur astronomers constantly know how much time passes between the disappearance of a star obscured by the Moon in a fraction of a second, and the trillions of years it takes for the Sun to change from black dust to a black dwarf. We touch ancient things so often that we become acutely aware of the vast span of time and the small space we occupy. Now. Unfortunately, we can’t stay long enough to witness major changes, but it’s nice to combine what science has discovered with happy hours under the starry sky to get an idea of ​​what has happened and will happen.

Variable stars, novae, supernovae, and a small number of binary and massive stars (such as Barnard’s star) change throughout a person’s lifetime. The rest of the universe is actually a series of still lifes. The Andromeda galaxy today looks the same to my flying eyes as it did in my bright-eyed youth. Almost everything moves too far and slow to be perceived by the human eye. What I would give to be a million years old and protect my health (and health insurance). That would be time enough to see large-scale changes in constellation outlines, star clouds turning into stars, and perhaps even a stunning supernova in the Milky Way.

We can use time-lapse photography to see how several space objects have changed over the past 100-odd years, and in some cases even less, leaving much to be desired. Changes in the structure of planetary nebulae, emission and reflection nebulae, supernova remnants, and stellar debris clouds are all fair game. Many of these then and now videos use images from the Hubble Space Telescope.

Amateur astronomers have created others, including excellent examples from Tom Polakis, an observer and research fellow at Lowell Observatory. By combining old and new footage into animated gifs that show real-world changes in their appearance, Polakis has created a slow-motion gallery of distant sky objects, variable stars, and supernovas. This is not an easy process.

“Even with software that uses multiple stars, alignment can be difficult,” Polakis said. Said. “But what’s more difficult is balancing the brightness and sharpness levels in the image pairs. The worst image of the two is the least common denominator that I try to match to some extent by adjusting the histogram levels and sometimes even blurring the better image.” Read more