swap_horiz HB 21 Alternatives
Looking for alternatives to HB 21? Compare the top Nebula options ranked by our AI scoring system.
HB 21
HB 21 is a mixed-morphology supernova remnant in Cygnus, discovered as a radio source in 1953 and known to interact with molecular clouds.
apps Top HB 21 Alternatives
The top alternative to HB 21 in 2026 is Eagle Nebula with a score of 9.7/10, followed by Tarantula Nebula (9.6) and Rho Ophiuchi Cloud Complex (9.5).
Eagle Nebula
The Eagle Nebula is Messier 16 in Serpens, famous for the Pillars of Creation, a star-forming column imaged by Hubble in...
Tarantula Nebula
The Tarantula Nebula is 30 Doradus in the Large Magellanic Cloud, the Local Group's most active star-forming region.
Rho Ophiuchi Cloud Complex
The Rho Ophiuchi Cloud Complex is a nearby star-forming region in Ophiuchus and Scorpius, notable for colorful reflectio...
Veil Nebula
The Veil Nebula is the visible part of the Cygnus Loop, a supernova remnant from a massive star that exploded about 10,0...
North America Nebula
The North America Nebula is NGC 7000, an H II region in Cygnus whose continent-like outline was named from Max Wolf's 18...
Vela Supernova Remnant
The Vela Supernova Remnant is the expanding debris of a nearby stellar explosion in Vela, notable for containing the Vel...
Lagoon Nebula
The Lagoon Nebula is Messier 8, an H II region in Sagittarius noted for active star formation and recorded by Giovanni H...
Omega Nebula
The Omega Nebula is Messier 17 in Sagittarius, a bright H II region discovered by Philippe Loys de Cheseaux in 1745 and...
Dumbbell Nebula
The Dumbbell Nebula is M27 in Vulpecula, discovered by Charles Messier in 1764 and widely cited as the first planetary n...
Egg Nebula
The Egg Nebula is CRL 2688, a bipolar protoplanetary nebula in Cygnus whose peculiar properties were first described fro...
Jellyfish Nebula
The Jellyfish Nebula is IC 443, a supernova remnant in Gemini known for interacting with nearby molecular clouds and lik...
W49B
W49B is a supernova remnant in Aquila, about 33,000 light-years away and notable for an asymmetric, possibly jet-driven...
W44
W44 is a mixed-morphology supernova remnant in Aquila, associated with pulsar PSR B1853+01 and roughly 20,000 years old.
Monoceros Loop
The Monoceros Loop is a large supernova remnant in Monoceros, recognized in 1963 and notable for its roughly 220-arcminu...
RCW 86
RCW 86 is a supernova remnant often linked to the guest star seen by Chinese astronomers in 185 CE, making it a candidat...
Footprint Nebula
The Footprint Nebula is M1-92, a bipolar protoplanetary reflection nebula in Cygnus discovered by Rudolph Minkowski in 1...
Puppis A Supernova Remnant
Puppis A is a supernova remnant in Puppis, notable for the fast-moving compact stellar remnant RX J0822-4300 left by the...
G1.9+0.3
G1.9+0.3 is a supernova remnant near the Galactic Center in Sagittarius, identified in 2008 as the youngest known remnan...
Gum Nebula
The Gum Nebula is a vast emission nebula across Vela and Puppis, named for Australian astronomer Colin Gum, who cataloge...
CTB 1
CTB 1 is a large supernova remnant in Cassiopeia, discovered as a radio source in 1960 and also known by the nickname Me...
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