In honor of the Hubble Space Telescope's 30th anniversary, NASA revealed 30 freshly processed images of space objects from the Caldwell catalog, a collection of star clusters, nebulae and galaxies that are bright enough to be spotted by amateur astronomers. That means you can not only enjoy the Hubble versions, you can also try to find them for yourself with the right gear.
This ghostly blob is planetary nebula NGC 40, also known as Caldwell 2. "A shell of gas is expanding outward from the nebula's central star, which has reached the final stage of its life," said NASA.
These celestial sparklers are Caldwell 14, better known as the Double Cluster of the Perseus constellation. "To the naked eye, the two clusters look like one large hazy patch, but binoculars and telescopes neatly split the pair, providing beautiful views of this celestial treasure," said NASA.
Caldwell 17 is a dwarf galaxy called NGC 147. This may be one of the more challenging Caldwell objects to find. "Dwarf satellite galaxies tend to appear very diffuse and dim, so they can be difficult to spot (especially in light-polluted or hazy skies)," said NASA. You'll need a dark area and a decent telescope to find this lovely galaxy.
Astronomers think there's a supermassive black hole at the heart of NGC 5005, a lovely spiral galaxy that is Caldwell 29. NASA said to look to the constellation Cane Venatici with a small telescope in order to find this one.
Spiral galaxy NGC 3626 (Caldwell 40) sports an impressive center known as a galactic bulge. "This structure is a densely packed region of stars that encompasses the heart of a spiral galaxy," said NASA. "Most galactic bulges host supermassive black holes, with the masses of the black hole and the bulge typically linked (bigger bulges harbor more monstrous black holes)."
Spiral galaxies are some of the most eye-popping objects out there in space. NGC 5248 (Caldwell 45) is another great example. NASA called out the notable ring structure around its nucleus, indicating starburst activity. "Starburst regions are sites where stars form at a much higher rate than usual," the agency said.
Up for a challenge? Then try to find dwarf galaxy IC 1613, also known as Caldwell 51, in the constellation Cetus. "Caldwell 51 is very difficult to spot and is one of the most elusive Caldwell objects," said NASA. "It appears as an extremely faint and diffuse smudge in the sky, even when viewed through moderately sized telescopes." Hubble was able to find it, but it's a tough one for amateurs.
Caldwell 52 (NGC 4697) is an elliptical galaxy located 40 million light-years away from Earth. "The galaxy's core can be spotted with a small telescope in a suburban sky. From a darker location, the galaxy appears as an elongated patch of fuzz," said NASA.
Caldwell 53 (NGC 3115) is an example of a lenticular galaxy. You'll note that it doesn't have the splashy arcing arms of a spiral galaxy. NASA said, "This galaxy, like most of its kind, hosts an elderly stellar population and has used up nearly all of its star-forming material."
Planetary nebula NGC 246 (Caldwell 56) takes on a blue hue in this processed Hubble Space Telescope image. "Planetary nebulae are named such because when they were first observed through early telescopes, they resembled planets," said NASA. "However, a planetary nebula is actually the final stage in the evolution of a star that is similar to our sun."
This gloriously spangled collection of stars has several names: Caldwell 58, NGC 2360 or Caroline's Cluster. The star cluster was named for German astronomer Caroline Herschel, who discovered it in 1783. "Caldwell 58 is an open cluster — a group of stars loosely bound together by gravity," NASA said.
Get your kicks looking at Caldwell 66. Globular cluster NGC 5694 is 100,000 light-years away in the constellation Hydra. You'll need at least a small telescope to spot it. Hubble was able to capture this wonderful view.
This ghostly nebula is Caldwell 68 (NGC 6729). "Reflection nebulae are star-forming clouds of gas and dust that glow with the energy emitted from a hot, nearby star," said NASA in describing the nebula as part of its Caldwell catalog of space objects imaged by Hubble.
Open star cluster NGC 2477 is listed at 71 in the Caldwell catalog of space objects visible to amateur astronomers. This Hubble image was newly processed in honor of the space telescope's 30th anniversary in 2020.
Hubble brings us this glittery look at Caldwell 73 (NGC 1851), a dense globular cluster of stars. NASA said it "can be spotted through a pair of binoculars, appearing as a fuzzy patch of light." A telescope will help clear it up.
This globular star cluster might look similar to a previous one you saw, Caldwell 73, but it's different. This one is Caldwell 78 (NGC 6541) and is best viewed through a small telescope in order to appreciate its dazzling characteristics. Or you can just stare into this Hubble image.
Caldwell 82 (NGC 6193) is a star cluster with some elbow room. It has around 30 stars, which are captured in wonderful detail in this Hubble image released in 2020 for the space telescope's 30th anniversary.
The Caldwell catalog of objects that can be spotted by amateur astronomers is full of star clusters, including this one as seen by Hubble. Caldwell 84 has a lovely round shape and is also known as NGC 5286.
Caldwell 87 (or NGC 1261) shows off another great Hubble Space Telescope view of a globular star cluster. Hubble's observations of star clusters like this one are helping astronomers better understand them. "It seems as though many globular clusters contain stars with varying chemical abundances, suggesting the stars are different ages," said NASA.
The Coalsack Nebula (also know as Caldwell 99) is quite a sight in this Hubble Space Telescope image newly processed for the telescope's 30th anniversary in 2020. This view shows just part of the nebula's edge.
"The object at the center of the image is a (much smaller) protoplanetary nebula," said NASA. "The protoplanetary nebula phase is a late stage in the life of a star in which it's ejected a shell of hydrogen gas and is quickly heating up."
The Caldwell 108 (NGC 4372) globular star cluster is one more sparkling entry among 30 newly processed images released by NASA in honor of the Hubble Space Telescope's 30th anniversary in 2020. That thin black line is just an artifact due to the way Hubble's camera system works.