NASA finds that there are far fewer galaxies than previously thought, with numbers in the billions rather than trillions
- Previous estimates suggest that there are about two trillion galaxies
- But new data from NASA’s New Horizons spacecraft suggests that this is not the case
- Instead, NASA now estimates that there are hundreds of billions of galaxies
NASA has revealed that there are far fewer galaxies in the universe than previously thought.
New measurements by NASA’s New Horizon spacecraft put the numbers at hundreds of billions, rather than the two trillion previously reported.
The findings indicate that the universe may be much less crowded than previous estimates suggest.
The Milky Way may be one of the only billions of galaxies in the universe, rather than trillions as previously estimated
In the study, NASA made new measurements of the faint glow of the background of unseen galaxies.
Mark Postman of the Baltimore Space Telescope Science Institute and lead author of the study, said: “It’s an important number to know – how many galaxies are there? We just don’t see the light from two trillion galaxies.
Previous estimates were based on observations of the deep sky made by NASA’s Hubble Space Telescope.
However, Hubble relied on mathematical models to estimate the number of galaxies, as many galaxies were believed to exceed the space telescope’s ability to detect in visible light.
Unfortunately, Hubble still suffers from light pollution from its position in the inner solar system.
To overcome this problem, NASA turned to the New Horizons spacecraft, which is experiencing an ambient sky 10 times darker than the darkest sky seen by Hubble.
Tod Lauer of NSF’s NOIRLab, lead author of the study, said: “These types of measurements are extremely difficult. A lot of people have been trying to do this for a long time.
“New Horizons has given us a point of view to measure cosmic optical background better than anyone has been able to do.”
NASA has headed for the New Horizons spacecraft, which experiences an ambient sky 10 times darker than the darkest sky seen by Hubble
To estimate how many galaxies are really there, the team analyzed existing images from New Horizons.
To remove the dim background light in some images, NASA was forced to remove the light from the Milky Way stars that was reflected in the camera.
Fortunately, the remaining signal was almost measurable, allowing a more accurate estimate of the number of galaxies.
NASA is now planning a follow-up study with its future James Webb space telescope.
NASA said: “NASA’s future James Webb space telescope could help solve the mystery. If fainting, individual galaxies are the cause, then Webb’s ultra-deep field observations should be able to detect them. ‘
This study is accepted for publication in the Astrophysical Journal.
WHAT IS A MONSTER GALAXY?
Monster galaxies, also known as starburst galaxies, are believed to be the ancestors of massive galaxies such as the Milky Way in today’s universe.
Ancient objects appeared shortly after the big bang and are characterized by the rapid formation of stars and the growth of mass, the birth of new stars at rates thousands of times higher than those of our own galaxy.
This leads to small but incredibly dense galaxies that burn rapidly through all their cosmic gas – the “fuel” used to create new stars.
Once they consume this gas, some within about 100 million years of birth become dormant or “red and dead” galaxies – common in our universe today.
Scientists hope that the study of mysterious objects will provide answers to key questions about the formation and evolution of modern galaxies, such as the Milky Way.
Monster galaxies, also known as star-blown galaxies, are believed to be the ancestors of massive galaxies such as the Milky Way in today’s universe. This image is an artist’s impression of ZF-COSMOS-20115, a monster galaxy discovered in 2017