The Hubble Space Telescope has now passed 25 years of service, so we took a look back at its biggest discoveries. As Hubble continues to operate from low-Earth orbit, a poll was taken from 100 international, professional astronomers to create this list.
1. The Cause of Gamma-Ray Bursts
Gamma-Ray Bursts (GRB) are rare and a typical galaxy will only experience a few in a million years. They are an incredibly powerful event and in just a few seconds they can release the same amount of energy as the sun would in 10 billion years. The Hubble monitored the aftermath of a GRB and spotted another cosmic explosion called a kilonova, which is understood to be the result of ‘neutron stars’ merging. This indicated that the GRB is created by a similar process.
2. How Planetary Collisions Work
For a month after 21 fragments of a comet hit Jupiter, the telescope monitored its scared atmosphere. Waves were emitted from the biggest impacts, like ripples in a pond which gave the opportunity to make calculations about the deep atmosphere and water below it.
3. Protoplanetary Discs
These look like small islands. The discs consist of cold dust and gas left over from the formation of a new star in the Orion nebula. Most of this dust and gas will dissapear over time but some will stick around and start to form a baby planet.
4. Calculating the Age of the Universe
Hubble observed the expansion of the spiral galaxy, M81, which through its expansion rate enabled the age of the universe to be calculated. Before Hubble was around the debate was whether the Universe was 10 or 20 billion years old, but Hubble observations have enabled a figure of 13.8 billion years to be placed on its age.
5. Supermassive Black Holes
Black Holes are tricky to find because not even light can escape their intense gravitational pull, which makes them invisible. Hubble has enabled us to identify the speed of objects and material around black holes which has made it possible to work out the mass.
6. Dark Matter
The galaxies, planets and stars that we can observe make up just 15% of the Universe’s matter. The other 85% is dark matter which emits nor absorbs no known wavelength of light, which acts as the scaffolding for galaxies to sit alongside. Hubble enabled scientists to create a 3D map of dark matter for the first time.
7. Generations of Stars
Globular Clusters are hundreds of thousands of stars that are bound together. Hubble examined a cluster named NGC2808 and discovered there to be 3 different generations of stars within it instead of the single generation expected.
8. Exoplanet Atmospheres
1890 planets have been identified as orbiting other stars than the Sun. Hubble has made it possible to detect the atmosphere around one of these exoplanets. Osiris is a planet which is 150 light years from Earth, which has a temperature of 1100 degree centigrade as it orbits its star which it is just 6.4 million kilometres away.
9. Accelerating Expansion of the Universe
The expansion of the Universe is accelerating and it is being driven by the phenomenon called ‘dark energy’. Hubble enabled supernovae to be monitored up to 10 billion light years away which enabled scientists to confirm that the expansion of the Universe was accelerating but had also had previously been decelerating in earlier times. Hubble helped indicate that the acceleration we see today started 5 billion years ago.
10. How Galaxies Evolve
One of Hubble’s most famous images is the Hubble Deep Field, which is a snapshot of a tiny patch of sky in the constellation Ursa Major. The image covers just one 24-millionth of the sky yet it contains around 3000 galaxies crowded together giving astronomers a massively valuable window into the past.