The mind-blowing images below show us wispy remnants of stars that exploded long ago and distant galaxies with energetic supermassive black holes at their centres.
What makes this set so interesting is that some of these distant cosmological marvels are invisible to the human eye. In order to create the beautiful pictures shown to the right, NASA has combined the light detected from several different telescopes.
The reason astronomers study light with different wavelengths and energies is because this technique illuminates the universe in ways that would otherwise remain hidden. And the more they see, the more astronomers can understand the cosmos.
What humans see is only a very small part of what scientists call the electromagnetic spectrum. This spectrum encompasses all forms of radiation — energy that moves through space. The term “visible light” refers to the part of the spectrum that we can see:
NASA’S different space telescopes all pick up electromagnetic radiation from different parts of this spectrum:
- Chandra X-ray Observatory detects X-rays
- Galaxy Evolution Explorer detects ultra-violet rays
- Hubble Space Telescope detects visible light
- Spitzer Space Telescope detects infrared light
NASA also uses telescopes on the ground like the Australia Telescope Compact Array, which detects radio waves, and the Digital Sky Survey, which (like Hubble) detects visible light.
Most of the pictures below are not what you would actually see if you were looking through a powerful telescope. In order to study objects in different wavelengths, astronomers convert the non-visible parts of the spectrum into colours like purple, blue, and red, which you see in the images below.
Astronomers can study the bones of stars that exploded in a brilliant light show, called a supernova, millions of years ago.
This image of a supernova remnant, called SNR 0519-69.0, is more than 163,000 light years away in a nearby galaxy called the Large Magellanic Cloud.
If you could hop on a spaceship and travel to this gaseous nebula, you might be disappointed. That’s because the image above is not what you would see in reality.
Below is a gif of the two real images — one of visible light from Hubble (which is what you could see through a telescope) and one of X-rays from Chandra — and then the final composite image. It’s amazing how NASA is able to combine them to create the final composite piece, using the special abilities of each individual telescope:
A Star Without A Pulse
The supernova remnant, called MSH 11-62, is a bit of a mystery. Judging from its shape, astronomers suspect that there is a rapidly rotating, extremely dense star, called a pulsar, toward the top of this cloud of gas.
Pulsars emit powerful pulses of high-energy radiation and that, together with their spinning rotation, produces a signature-shaped, elongated cloud, like the one in the composite below. But astronomers have yet to detect any pulses within the distant nebula.
Radio waves are lower in energy than visible light or X-rays, so they’re good for detecting low-temperature gas, which shows up in the purple image below:
Millennia In The Making
About 2,000 years ago, ancient Chinese astronomers recorded a “guest star” that seemingly appeared out of nowhere and remained visible for eight months. Modern astronomers suspect that this guest star was a supernova and that the composite image below is the left-over guts of what remains of that star.
The false-colour picture above is made from combining a Hubble shot in visible light and a Chandra image in the X-ray part of the spectrum (blue/purple). See how NASA puts these two images together in the animation below:
Hungry, Hungry Black Holes
Located 700 million light years from Earth is the Cygnus A galaxy. This is a fascinating example of the power of supermassive black holes. Cygnus A is known as an active galaxy because the supermassive black hole at its center is emitting large amounts of radiation into space, which this image highlights in blue and red.
In reality, this galaxy looks nothing like the image above. But with the help of Chandra and NSF’s Very Large Array radio telescope, astronomers can see the dynamic nature of this galaxy’s center.
The false-colour image above is made from three photos taken by Chandra in X-rays (blue), NSF’s Very Large Array in radio waves (red), and Hubble in visible light. (Here, red is a false colour and not what you would see in reality, unlike the true red colour in the earlier Hubble image of SNR 0519-69.0.)
Check out the stark contrast in temperature of the hot X-rays around the center versus the low-temperature gas that the black hole has ejected millions of light years away.
The Most Picturesque Of All?
Last but not least is one of the most picturesque galaxies in the universe: the Whirlpool galaxy. This galaxy floats in space 21 million light years from Earth and is part of a class of galaxies called spiral galaxies because of their distinct spiral arms swirling out from the center.
Spiral galaxies are particularly interesting to astronomers because our home galaxy, the Milky Way, is also a spiral galaxy. Learning more about other spiral galaxies gives insight to our own.
The false-colour image above is made from four photos taken by Chandra in X-rays (purple), the Galaxy Evolution Explorer in in ultraviolet (blue), Hubble in visible light (green), and the Spitzer Space Telescope in the infrared (red).
Astronomers study objects in infrared (red) wavelengths because, as with radio waves, infrared shows low-temperature gas. At higher energies, in ultra-violet (blue) wavelengths, astronomers can detect pockets of star formation.
With that in mind, check out the level of activity at the galaxy’s center in all of the images below: The infrared indicates that there’s a great deal of dust around the center; the ultra-violet points to bright spots of star formation; visible light shows dark patches where gas is blocking the light; and the X-rays highlight blazing-hot gas, which the supermassive black hole at the center is shooting off into space.
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