NASA finds that there are far fewer galaxies than previously thought, with numbers in the billions instead of trillions
- Previous estimates suggested there were about two trillion galaxies
- But new data from Nasa’s New Horizons spacecraft suggests 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 taken by Nasa’s New Horizon spacecraft came in at hundreds of billions, instead of the previously reported two trillion.
The findings indicate that the universe may be a lot less crowded than previous estimates suggested.
The Milky Way may be one of the few billions of galaxies in the universe, rather than trillions as previously estimated
In the study, NASA took new measurements of the faint background glow of invisible galaxies.
Mark Postman of the Space Telescope Science Institute in Baltimore, and a lead author of the study, said: “It’s an important number to know – how many galaxies are there? We simply do not see the light of two trillion galaxies. ‘
Previous estimates were based on deep-sky observations by Nasa’s Hubble Space Telescope.
However, Hubble relied on mathematical models to estimate the number of galaxies, as many galaxies were thought to be beyond the space telescope’s ability to detect in visible light.
Unfortunately, Hubble is still suffering from light pollution due to its position in the inner solar system.
To solve this problem, Nasa turned to its New Horizons spacecraft, which experiences an ambient sky 10 timers darker than the darkest sky seen by Hubble.
Tod Lauer of NSF’s NOIRLab, a lead author of the study, said, “Measurements like this are extremely difficult. Many people have tried this for a long time.
“New Horizons provided us with a vantage point to measure the cosmic optical background better than anyone has ever been able to do.”
Nasa turned to its New Horizons spacecraft, which experiences an ambient sky 10 timers darker than the darkest sky seen by Hubble
To estimate how many galaxies actually exist, the team analyzed existing images from New Horizons.
To tease the faint background glow in some images, Nasa was forced to remove light from Milky Way stars reflected off the camera.
Fortunately, the remaining signal was nearly measurable, allowing for a more accurate estimate of the number of galaxies.
Nasa is now planning a follow-up study with the upcoming James Webb Space Telescope.
Nasa said, “NASA’s upcoming James Webb Space Telescope may be able to help solve the mystery. If faint individual galaxies are the cause, Webb ultra-deep field observations should be able to detect them. ‘
This study has been 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.
The old objects appeared shortly after the Big Bang and are characterized by rapid star formation and mass growth, with new stars thousands of times higher than those of our own galaxy.
This leads to small but incredibly dense galaxies that quickly burn out all of their cosmic gas – the ‘fuel’ used to create new stars.
Once they have used up this gas, some within about 100 million years of birth, they become quiet or ‘red and dead’ galaxies – which are common in our universe today.
Scientists hope that studying the mysterious objects will answer important questions about the formation and evolution of modern galaxies, such as the Milky Way.
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. This image is an artist’s impression of ZF-COSMOS-20115, a monster galaxy discovered in 2017