There are so many astronomical objects out there behaving in mysterious ways that astronomers are still trying to figure out. A brand new set of words and language has to be invented every time something is discovered and that is part of what makes the study of space so interesting. There’s so much out there that is waiting to be found.
The use of mythological and ancient names to name all the objects that are in space has also always given astronomy an air of mystery and wonder that attracts all kinds of people and incentivizes them to look at the sky every night.
There are so many space-related words and terms that it is hard to keep up.
This is why below, we have compiled a list of space words that start with O so you can learn more about the study of the universe. These are words that are related to astronomy and space, if what you are looking for is specifically for name ideas or the names of objects, check out our lists of star names, planets, or constellations. You will also find those sorted by letter.
| Word | Meaning |
|---|---|
| O-type Star | A massive and extremely hot star of spectral type O. |
| Oberon | One of the major moons of Uranus, discovered by William Herschel in 1787. |
| Oblateness | The flattening of a celestial body at its poles due to its rotation. |
| Observatory | A facility equipped for observing celestial objects and phenomena. |
| Occam’s Razor | The principle that, among competing explanations, the simpler one is usually preferable. |
| Occulting Disk | A device used in telescopes to block out the light of a bright object to observe a fainter one. |
| Omega Centauri | A globular cluster in the Centaurus constellation, one of the brightest and largest known. |
| Omega Nebula | A large emission nebula in the Sagittarius constellation. |
| Oort Cloud | A theoretical region of icy bodies at the edge of the solar system. |
| Open Cluster | A group of relatively young stars that formed from the same molecular cloud. |
| Ophiuchus | A constellation located near the celestial equator, often depicted as a serpent-bearer. |
| Orbit | The path that a celestial body takes around another due to gravitational forces. |
| Orbit Insertion | The process of placing a spacecraft into its intended orbit around a celestial body. |
| Orbital Velocity | The minimum velocity needed for an object to maintain a stable orbit around a planet or star. |
| Orion | A prominent winter constellation, named after the hunter from Greek mythology. |
| Orion Nebula | A diffuse nebula in the Orion constellation, a region of active star formation. |
| Osiris | An asteroid in the outer asteroid belt, named after the Egyptian god of the afterlife. |
| Oumuamua | An interstellar object that passed through the solar system, believed to be an elongated asteroid or comet. |
| Outer Galaxy | The region of a galaxy located away from the galactic center, typically containing spiral arms. |
| Outer Planets | The gas giant planets (Jupiter, Saturn, Uranus, Neptune) located beyond the asteroid belt. |
| Outer Space | The vast expanse beyond Earth’s atmosphere containing stars, planets, and other celestial objects. |
| Owl Cluster | A nickname for Messier 103, an open cluster of stars in the Cassiopeia constellation. |
| Owl Nebula | A planetary nebula in the constellation Ursa Major, known for its resemblance to an owl’s face. |
| Ozone Layer | A layer of ozone high in Earth’s atmosphere that absorbs most of the Sun’s ultraviolet radiation. |
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