- Researchers created a mosaic of the distant universe, using 16 years of Hubble’s observations.
- It contains 265,000 galaxies that stretch back to 13.3 billion years.
The universe is nearly 13.8 billion years old, which means the light we see in distant space has to have been traveling for at 13.8 billion years or less. But since the universe is expanding all of the time, the edge of the ‘observable universe’ lies about 46 billion light-years away.
Before the launch of NASA’s Hubble Space Telescope in 1990, we were able to observe galaxies up to 7 billion light-years away. Also, ground-based telescopes were not advanced enough to explain the formation and evolution of galaxies in the early universe.
Now, astronomers have used 16 years of Hubble’s’ observations to develop a mosaic of the distant universe. They have named this picture Hubble Legacy Field. It consists of approximately 265,000 galaxies that stretch back to 13.3 billion years.
The mosaic’s wavelength ranges from UV to near-infrared light, thus it captures all essential elements of the galaxy. The farthest and faintest galaxies in the picture are nearly 10 billion times less bright than what human eyes can see.
The image is made by combining observations carried out by multiple Hubble deep-field surveys.
- In 1995, Hubble recorded thousands of previously unknown galaxies.
- In 2004, Hubble Ultra Deep Field generated a single image featuring about 10,000 galaxies.
- In 2012, Hubble eXtreme Deep Field combined observations taken over the past decade of a small region of sky in the constellation of Fornax.
Reference: European Space Agency
The new series of Hubble Legacy Field images is generated from 7,500 individual exposures. It’s a result of 31 Hubble programs conducted by different teams of researchers. The telescope has spent over 250 days on this region only. Whereas, the second series of images features over 5,200 Hubble exposures.
A wide range of sensitive color channels is now available to observe distant galaxies. These images also make it possible to study young and old stars and active galactic nuclei within galaxies.
Wide View of Universe | Credit: NASA/ESA
Hubble Legacy Field reveals the evolution of galaxies in the most simple way possible: it’s similar to watching individual frames of a movie. This can help researchers trace the expansion of the universe and better understand the underlying physics. The findings also reveal when chemical elements enabled the conditions which ultimately led to the emergence of life.
Overall, the picture yields a massive catalog of galaxies in the distant universe. Such high-resolution measurements make extragalactic study feasible. The successor of the Hubble, James Webb Space Telescope is planned to be launched in 2021. It will provide more detailed images, revealing every aspect of how the distant galaxies evolved over time.