Hubble creates stunning mosaic containing roughly 265,000 galaxies
The mosaic is a collective of nearly 7,500 individual images
The Hubble Space Telescope has been an essential tool in helping us understand our origins, peering back in time as it photographs the most distant objects in our universe. Now, astronomers have used the telescope to photograph 265,000 galaxies that go back to just 500 million years after the Big Bang.
The assembled image comes from 16 years of observations from the jointly run NASA and European Space Agency (ESA) telescope and is part of the Hubble Legacy Field.
The mosaic is a collective of nearly 7,500 individual images, from 31 teams working with Hubble for a total of 250 days.
The field of view is just roughly the size of a full moon in the sky. You can click here for a zoomable image.
Hubble's first deep sky image was made in 1995, just five years after it launched into orbit around Earth. Hubble pointed to a small patch of sky over 10 days in December of that year, producing 100 hours of total exposure time (like leaving the shutter open on your camera). Astronomers were stunned to see more than 3,000 galaxies.
A second deep-field image, called the Hubble Ultra Deep Field, was taken in 2003–2004 after a new camera — the Advanced Camera for Surveys — was installed. The telescope took more than 800 exposures for a total time of 11.3 days.
Back in time
When we're looking at objects in space, we're looking back in time. Light from the sun takes about eight minutes to reach us. Even light from the moon takes roughly 1.3 seconds to reach us. So when we're looking at distant galaxies, we are looking back in time.
In the case of the Hubble Ultra Deep Field, the image captured 10,000 galaxies. Of those, 100 of them were some of the most distant known at the time, existing when the universe was just 800 million years old.
In 2012, a decade of observations were combined to produce the Hubble eXtreme Deep Field image. The image revealed more than 5,000 galaxies in an area of the sky that was just a tenth of the width of the full moon.
Trying to capture the most distant galaxies is no easy feat: because they're so far, they're also extremely dim. That's why Hubble is pointed to a particular part of the sky for so long with its camera lens open for long stretches. This way, it is able to capture more light, revealing what was once hidden.
Next up will be a second Hubble Legacy Field that will contain more than 5,200 Hubble exposures.