Make Your Vocabulary Skyrocket With These Space Words

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Our universe is unfathomably huge and getting bigger all of the time, according to the Big Bang model and the theory of universe expansion. That’s a pretty cool concept and term, right? As the theory goes, dark energy (more on this later) is causing the universe to continually stretch itself.

Studying the universe introduces us to some fascinating concepts in general: black holes, rogue planets, Oort clouds—and white holes, too? If you are a casual space explorer, you probably already know stellar objects like comets, asteroids, meteors, and galaxies. But there is so much more out there for you to discover! Jump in our (word) rocket ship as we boldly discover some awesome intergalactic words.


From Earth, a pulsar resembles a flickering star. In reality, a pulsar is a neutron star—a really dense object left over when a big star dies—that radiates beams of light in two directions. The pulsar rotates as it shines light beams, which makes it appear to blink or pulse as it spins away from Earth and points its lights in other directions.


Asterism is a fancy word that means “a group of stars.” So, what makes an asterism different from a constellation? The 88 constellations in the sky have officially recognized names and shapes. Asterisms are those other groups of stars that aren’t officially recognized but still have popular names. The Big Dipper (part of Ursa Major) and Orion’s Belt (part of Orion) are two examples of commonly known asterisms.


Just like the Earth, the Sun has an atmosphere surrounding it. The outermost layer of the Sun’s atmosphere is called the corona. Because the Sun is so bright, you can only see the corona during a total solar eclipse. The Sun’s corona is very dense and, mysteriously, has a much higher temperature than the Sun itself.


A facula (plural faculae) is an unusually bright spot on the surface of the sun. A facula is smaller and harder to see than the more well known sunspots. Both faculae and sunspots are caused by bubbles of hot gas and both are used to keep track of the solar cycle. As one last bit of trivia, the word facula is Latin for “little torch.”


A nebula is a cloud of dust and gas in outer space. While that may not sound terribly exciting, nebulae act as star nurseries as they have the perfect conditions that new stars need to form. The word nebula comes from Latin and means “mist,” “vapor,” or “cloud.”


A planetesimal is a small celestial object formed from dust, rocks, and other materials. According to one theory, planetesimals may be the building blocks that combined together to form the early planets of the universe. Planetesimals may have also played a part in the formation of the Earth’s moon and some of the other moons in our solar system as well.

Do you know the difference between a meteor, comet, and asteroid?

rogue planet

A rogue planet is a planet that doesn’t orbit a star. Many planets, like Earth, are part of a solar system and orbit around a central star. Rogue planets, on the other hand, are not confined to drift around a star and roam wherever they want across space. Because they aren’t next to a star and don’t emit light themselves, rogue planets are very hard for astronomers to find. Despite their lack of starry friends, evidence suggests that it may be possible for life to exist on rogue planets.

white hole

As you likely know, a black hole is a region of space where the gravity is so intense that not even light can escape. We often imagine black holes as terrifying objects that suck in all the matter around them.

A white hole is the theoretical opposite of a black hole, a celestial object that would endlessly expel matter out of it. According to Albert Einstein’s theories, black holes and white holes serve as the entrance and exits of wormholes that would allow travel through time and space. Other modern theories propose that a white hole could theoretically exist as the final stage of a black hole, where all of the mass sucked into a black hole is released back out again.


A quasar is a celestial object located very far away from us in distant galaxies. Quasars are a result of gas and stars accumulating into a disk around a gigantic black hole. This disk emits a huge amount of heat, making quasars some of the brightest objects in all of the known universe. Quasars also emit radiation (and in some cases, radio waves) into space, which is how we have been able to find them. In fact, the name quasar is short for “quasi-stellar radio source,” which refers to the radio telescopes that were first used to detect them.


A blazar is basically identical to a quasar except for one quality: its angle toward Earth. Typically, a quasar is angled slightly toward Earth; that means we can detect its light and radio wave emissions. A blazar is angled directly toward the Earth so that the light and radiation shoots directly toward us. This difference in angle makes a blazar appear even brighter than an already absurdly luminous quasar.

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Oort Cloud

The Oort Cloud is the furthest outer region of our solar system, being more than a thousand times away from the Sun than Pluto is. The Oort Cloud is often imagined as a bubble of icy objects that exists around our solar system. The Oort Cloud could possibly contain trillions of celestial objects and is the source of many comets that pass through our solar system. The Oort Cloud is named for astronomer Jan Oort, who originally theorized its existence.

dark matter

Dark matter is a theoretical, invisible form of matter that exists in space. The word matter is used to refer to all of the stuff that takes up space as we know it. In outer space, everything is positioned where it is because of gravity. We can see what is going on in outer space because of light. However, there are areas of outer space where astronomers can detect mass (due to gravity) but nothing in that area is emitting or absorbing light. Because something must be there, this invisible “missing mass” is known as dark matter.

According to scientific estimates, dark matter makes up about 27 percent of space. This may not sound like much, but the “regular matter” that makes up our Earth and all the suns and planets accounts for less than 5 percent of the universe! But wait, we are only at about 32 percent of the universe. What is the rest of it made of?

dark energy

The answer, according to modern science, is dark energy. Dark energy is a theoretical form of energy that exerts negative, repulsive pressure. In the simplest sense, dark energy is basically “reverse gravity” that causes things to repel away from each other rather than attract each other as is the case with gravity. Dark energy is thought to be responsible for the expansion of our universe and is what the “empty space” of outer space is believed to be made out of.


No, a cat didn’t just walk across the keyboard. In astronomy, a syzygy is an alignment of three celestial objects. For example, when the Earth, sun, and moon are all positioned in a line to cause an eclipse, they are aligned in syzygy. This incredibly cruel word to use in a game of Hangman comes from the Greek word syzygía, meaning “union” or “pair.” In addition to syzygy, other cool words that astronomers use to refer to space observations include azimuth, parsec, ephemeris, and albedo.

Hyperjump over to take the quiz!

Did this list of cosmic words launch you into the stratosphere? You can jump into the void and review this expansive list of terms and their meanings with our word list here. Or, demonstrate your new grasp of space by heading to our short quiz on these words.

Take another outer space word trip right from your home with these words.

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