Since its mission began in 1990, the Hubble Space Telescope has made more than a million observations. Here are just a few of its most important revelations.
Hubble has uncovered a plethora of strange galaxies in various stages of maturity and interaction with one another.
Its views of galaxy mergers offer us a preview of the inevitable collision between our own Milky Way Galaxy and the neighboring Andromeda Galaxy billions of years from now.
Hubble's studies of exploding stars called supernovae (like the one at lower left) helped show that the universe is not just expanding, but expanding faster and faster – a discovery that led to the 2011 Nobel Prize in Physics.
The mysterious force behind this accelerated expansion, called dark energy, pervades the universe.
After astronomers discovered ripples in spacetime called gravitational waves from a neutron-star collision in the galaxy NGC 4993, Hubble detected visible light from the associated kilonova and watched it fade away over several days.
A kilonova happens when a pair of compact objects such as neutron stars crash together.
This was the first time visible light from a gravitational-wave event had ever been seen.
A flash of light from a red supergiant star called V838 Monocerotis lit up nearby clouds of dust in a phenomenon called a light echo.
A series of Hubble images captured this remarkable reverberation of light.
These ground-breaking discoveries represent a mere fraction of what Hubble has taught us so far and what the telescope will continue to reveal as it continues to explore the universe over the years to come.
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Credit: NASA Goddard Space Flight Center
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