To celebrate International Astronomy Day (May 7), we are highlighting this post from ScIU’s archives! It was originally published by Jennifer Sieben in April 2020 and has been lightly edited to reflect current events.
April 24th, 2020 was the 30th anniversary of the launch of perhaps the most famous telescope: the Hubble Space Telescope. Orbiting the earth, this telescope has changed the way astronomers and the public alike view the universe. With over 1.4 million observations, providing data for more than 16,000 peer-reviewed scientific papers, Hubble has exceeded expectations.
If you have ever seen an image of a spiral galaxy as a desktop background, textbook cover, or in the background of an inspirational quote, the chances are high that it was taken by Hubble. Images like these highlight the spectacular beauty of our universe and are often a great tool to encourage interest in science. Hubble images demonstrate that science can be more than a mixture of numbers and buggy code; it can also be spiral galaxies that show where new stars are being formed and remind us that the mystery of galaxy formation is still unsolved. New data received from Hubble constantly challenges our preconceived notions about the universe.
Hubble’s main science objective was to determine the size and age of the universe. To do this, astronomers measure the changing brightness of Cepheid variable stars, stars that have a varying brightness that follows a regular shape, but the frequency of the pattern is dependent on the actual luminosity of the star. Astronomers use the frequency of this pattern to determine how far away a galaxy is. Hubble’s large mirror helped detect Cepheid variable stars at farther distances, and the expansion and age of the universe was confirmed. Moreover, this same high resolution allowed for even more distant supernovae observations that showed the universe’s expansion is accelerating. This completely changed the field of cosmology and led to the 2011 Nobel Prize in Physics.
Closer to home, Hubble was also instrumental in the New Horizons mission. Hubble took images of the Pluto system from the early 1990s to 2010 in order to prepare for the flyby of New Horizons. And it was a good thing it did: Hubble discovered four of Pluto’s moons, and the mission scientists used these data to avoid a collision.
After capturing gorgeous images of Pluto, New Horizons then flew past the duck-shaped Kuiper Belt Object Arrokoth, another object discovered by Hubble. Without the space telescope, we never would’ve gotten to see this bizzare object and the mission would’ve ended much sooner.
Astronomy is a science of many surprises, and putting a telescope in space only revealed more. One such image was the Hubble Deep Field. The telescope pointed its camera to a part of the sky that appeared practically empty to all previous observations. And then, it left the shutter open for ten days, collecting all the light from a seemingly empty part of space. By using a long exposure, just like a traditional camera on Earth, astronomers were able to see what was hiding in the dark. This image is only 1/30th the size of the full moon, and yet it revealed 3,000 galaxies, several hundred of which had never been seen before.
Due to the long lifetime of the Hubble Space Telescope, astronomers have been able to view the unprecedented: motion and changes in the shapes of stellar jets over time. Stellar jets are caused by gas swirling into newly forming stars, some of which is then channeled by magnetic fields and shot from the poles of the spinning stars in opposite directions at supersonic speeds. Looking in the infrared, these energetic jets of glowing gas emitted from young stars can be seen in unparalleled detail. Many observations over time have been invaluable to understanding the cause of these jets and the environment in which stars are born.
Hubble lasted many more years than expected, with many shuttle missions providing repairs to the aging equipment. But as the telescope enters its 4th decade of science, it will be retired soon. There is no one telescope planned that will replace this grand observatory, but a combination of the James Webb Space Telescope (JWST) and the Wide Field Infrared Survey Telescope (WFIRST) may come close. Both telescopes will have greatly advanced camera technology, in addition to larger mirrors that can collect more light (similar to leaving a camera shutter open longer, leading to greater depth and detail). Together, they will cover the wavelength range that Hubble operated in, while also reaching beyond. I cannot wait for the next generation of space telescopes to surpass Hubble and illuminate even more wonders of the universe.