Nasa has revealed that there are far fewer galaxies in the universe than previously thought.
New measurements taken by Nasa's New Horizon spacecraft put numbers in the hundreds of billions, rather than the previously reported two trillion.
The findings indicate that the universe may be a lot less crowded than previous estimates suggested.
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 don't see the light from 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 be beyond 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 issue, 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 on the study, said: 'These kinds of measurements are exceedingly difficult. A lot of people have tried to do this for a long time.
'New Horizons provided us with a vantage point to measure the cosmic optical background better than anyone has been able to do it.'
To tease out the faint background glow in some images, Nasa was forced to remove light from Milky Way stars that was reflected into the camera.
Thankfully, the remaining signal was just about measurable, allowing for a more accurate estimate of the number of galaxies.Nasa is now planning a follow-up study with its 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, then Webb ultra-deep field observations should be able to detect them.'
This study is accepted for publication in the Astrophysical Journal.