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NASA finds that there are far fewer galaxies than first thought, with numbers in the billions rather than trillions
- Previous estimates suggested there were around 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 by NASA’s New Horizon spacecraft have yielded hundreds of billions, rather than the previously reported two trillion.
The results indicate that the universe may be much less crowded than previous estimates suggested.
The Milky Way may be one of only billions of galaxies in the universe, rather than trillions as previously estimated.
In the study, NASA took further measurements of the faint backdrop of invisible galaxies.
Mark Postman of the Space Telescope Science Institute in Baltimore, and lead author of the study, said, “That’s an important number to know – how many galaxies are there? We just don’t 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 believed to exceed the space telescope’s ability to detect in visible light.
Unfortunately, Hubble still suffers from light pollution due to its position in the inner solar system.
To overcome 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, lead author of the study, said: “These types of measurements are extremely difficult. Many people have tried to do this for a long time.
“New Horizons has provided us with a vantage point to measure the cosmic optical background better than anyone has been able to.”
NASA turned to its New Horizons spacecraft, which experiences an ambient sky 10 timers darker than the darkest sky seen by Hubble
To estimate the actual number of galaxies, the team analyzed existing images from New Horizons.
To bring out the faint background glow in some images, NASA was forced to remove the starlight from the Milky Way that was reflected back into the camera.
Fortunately, the remaining signal was roughly measurable, allowing a more accurate estimate of the number of galaxies.
NASA is currently planning a follow-up study with its upcoming James Webb Space Telescope.
NASA said: ‘NASA’s upcoming James Webb Space Telescope could help solve the mystery. If weak individual galaxies are the cause, then Webb 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 star galaxies, are believed to be the ancestors of massive galaxies like the Milky Way in today’s universe.
Ancient objects appeared shortly after the Big Bang and are characterized by rapid star formation and mass growth, giving rise to new stars at rates thousands of times higher than in our own galaxy.
This leads to small but incredibly dense galaxies that quickly burn off all of their cosmic gas – the “fuel” used to create new stars.
Once they have used up this gas, some within 100 million years of birth, they become quiet or “red and dead” galaxies – common in our universe today.
Scientists hope 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 galaxies, are believed to be the ancestors of massive galaxies like the Milky Way in today’s universe. This image is an artist’s impression of ZF-COSMOS-20115, a monster galaxy discovered in 2017
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