Tied with the Big Dipper for the biggest celebrity constellation, Orion is the great hunter in our night sky. If you look carefully on a clear night, you can see the great Orion Nebula right beneath Orion’s belt. The nebula contains on estimated 2,000 times the mass of our Sun and is one of the best—observed stellar nurseries — a hotbed of new stars. Observing the Orion Nebula has helped astronomers understand more about how stars and planets form.
Incredibly vast and only 1,600 light years away from us, if the North America Nebula were brighter, it would be the size of the full Moon in our sky. If we scaled the nebula down to the actual size of North America, the Earth would be the size of a grain of sand.
“Lagoon” is what you name a nebula that doesn’t look like anything. This amorphous nebula is actually pretty close to us, as far as nebulas go — only 4,100 light years away. It’s one of only two nebulae visible to the naked eye (from the northern hemisphere), but it’s pretty dim so don’t get your hopes up.
This epic space rose is 5,219 light years away from us in the Milky Way, and stretches 130 light years across. If it were the size of an actual rose, the Milky Way would be a pond 60 m across that the rose was floating in.
Omega Centauri is a vast “globular cluster”, a tightly grouped bunch of stars. 15,800 light years away and 150 light years across, Omega Centauri is the size of the full Moon in our night sky and can be seen in rural areas on clear nights. Containing 4 million solar masses, Omega Centauri is the largest, brightest, and most massive known globular cluster in the Milky Way. Some astronomers hypothesize that Omega Centauri is the remnant of a dwarf galaxy that merged with the Milky Way.
Messier 54 is a globular cluster astronomers originally thought was in the Milky Way. Then in the 1990s it come out that this whole time, Messier 54 has been in the Sagittarius Dwarf Elliptical Galaxy instead. Not really sure how you make that mistake.
The Great Nebula in Carina, formally called NGC 3372, lies in one of the brightest ports of the Milky Way. It boasts several massive stars and other nebulae — you know, the usual. The most energetic star within this nebula used to be the brightest star in the sky around 200 years ago — then it slowly faded. Take that as a lesson, kids, even interstellar fame isn’t forever.
Not all nebulae are worth talking about.
Residing in the Large Magellanic Cloud, this giant spider is the largest known nebula — almost 10,000 times the length and a trillion times the volume of the smallest nebulae. If the Sun were the size of a grain of sand, and the largest stars were the size of cars, and the smallest nebula were 1.5 km wide, the Tarantula Nebula would be 10% bigger than the Earth! The nebula houses R136, the most productive star formation hotspot known in the Local Group of galaxies.
A couple of years ago astronomers had a riddle to solve. The theory of the Big Bang predicts that larger galaxies like the Milky Way are surrounded by a couple hundred dwarf galaxies — the galactic version of moons, orbiting Ground larger galaxies. But only a dozen have been discovered yet. One possible explanation is so-called “galactic cannibalism”. Larger galaxies have such intense gravitational fields that they suck up smaller surrounding galaxies, like the time the Milky Way ate the Sagittarius Dwarf Elliptical Galaxy for breakfast.
Recent analyses of the Leo 2 Dwaric galaxy indicate that it consists of older stars, suggesting that it somehow managed to go this whole time without being eaten by the Milky Way. This is kinda badass of it, since it is only 2,400 light years across, just a bit bigger than the largest nebulae. If the Milky Way were the size of a frisbee, Leo 2 would be a 3 mm pebble.
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