Astronomers reveal how night sky will change in 1000 years

Fate of giants in space and possible Betelgeuse explosion

Much depends on the lifespan of individual stars. Most of the stars in our galaxy are small. However, the constellations we observe are dominated by large and bright stars. The larger the star, the shorter its life and the faster it will disappear from our sky.

Stars whose mass exceeds the solar mass by about eight times or more end their lives with a catastrophic core collapse, turning into supernovae. These powerful explosions are not only spectacular, but also mark the disappearance of stars from our sky.

Many astronomers believe that Betelgeuse, a red supergiant, will be the first star to disappear. It could happen tomorrow or in 100,000 years. When the star explodes, it will become brighter than the full moon, so much so that it can be seen during the day.

It is difficult to predict exactly when such stars explode, but one possible signal is a stream of ghostly particles called neutrinos. During a supernova explosion, most of the energy is released in the form of neutrinos, not in visible light.

“The neutrino production from Betelgeuse will ramp up in the last phases of its life so that in the last day, it will emit enough neutrinos that our current detectors will see it,” explains Brian Fields, a supernova expert at the University of Illinois. We will have about 24 hours to prepare for the spectacle.

Such a powerful explosion may sound threatening, but according to Fields, the Earth is too far away to feel its effects. For a supernova to have an impact on life on Earth, it must be within 8-10 parsecs, which is about 2 million times farther than the distance from Earth to the Sun.

“If we had anything that close, it would be by far be the brightest star in the sky,” says Fields.

How movement of stars will change shape of familiar constellations

While a supernova seems like a more dramatic event, it's the movement of stars that plays a major role in changing constellations.

Every star in our galaxy is in motion. From Earth, this is called proper motion, the amount by which the apparent position of a star changes over time. The fastest star in this regard is Barnard's Star, which moves at a speed of 10 angular seconds per year. This means that in 180 years it will move a distance equal to the diameter of the full Moon.

Most stars move much more slowly. That's why the constellations we see today have remained virtually unchanged since the time of Ancient Greece. However, over tens of thousands of years, these shifts add up to radically change the shape of the constellations.

Take, for example, the Big Dipper, or more precisely, the asterism Big Dipper. The five central stars of the Bucket appear to be close together not only from our perspective, but in reality, they are close to each other. They were born together and are a “moving group” moving across the sky in the same direction. However, the two outermost stars move in different directions.

“Over time, the Big Dipper will morph and won't look like a spoon at all. Enough of it will change that it will look 'freaky deaky' after tens of thousands of years,” explains Brian Fields.

Because these changes take place over tens of thousands of years, not tens of millions, as in the case of supernovae, the stars' own motion will affect the constellations long before they disappear.

The night sky is affected not only by the movement of the stars, but also by the Earth itself. Our planet oscillates like a spinning top, changing the direction of the North Pole. This process is called precession.

“The Egyptians used to have a different north star. At the time of the Pyramids of Giza, [their north star] would be Alpha Draconis,” says supernova researcher Kayleigh Excell.

Our constellations change not only because of the movement or death of stars. New stars continue to be born in the galaxy. Over time, they emerge from their nebulae, and if they are bright enough, they will take their place in future constellations.