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 J 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 |
|---|---|
| J2 Effect | A gravitational effect caused by the oblateness (flattening at the poles) of a planet, which affects the orbits of satellites and spacecraft. |
| J2000 Epoch | The standard reference epoch used for specifying celestial coordinates, often referred to as the Julian year 2000. |
| JPL | Jet Propulsion Laboratory, a research and development center managed by NASA that focuses on space exploration and robotic missions. |
| Jack-o’-lantern Nebula | A nebula in the constellation Cepheus, named for its pumpkin-like appearance in certain images. |
| Jackson’s Star | A historical name for the star Eta Carinae, a massive and highly unstable star in the Carina Nebula. |
| Jacob’s Ladder Nebula | A faint and intricate reflection nebula in the constellation Centaurus, resembling the rungs of a ladder. |
| Jacobi Constant | A constant of motion used in the study of celestial mechanics, particularly for understanding the stability of orbits in a three-body system. |
| Jacobi Ellipsoid | A theoretical model of an oblate spheroid used to describe the equilibrium shape of a rotating, fluid celestial body. |
| James Webb Space Telescope | A large, infrared-optimized space telescope set to replace the Hubble Space Telescope, designed to observe the universe in unprecedented detail. |
| Jansky | A unit of measurement used in radio astronomy to quantify the strength of radio signals from celestial sources. Named after Karl Jansky, a pioneer in radio astronomy. |
| Janssen Crater | A prominent impact crater on the Moon, named after Pierre Janssen, a pioneer in spectroscopy. |
| Janus | A small moon of Saturn, one of its shepherd moons, which helps maintain the shape of the planet’s rings. |
| Jarnsaxa | A moon of Saturn, named after a giantess in Norse mythology and part of the Norse group of Saturnian moons. |
| Jeans Instability | A gravitational instability that can lead to the collapse of a gas cloud and the formation of stars or other celestial bodies. |
| Jeans Length | The minimum size a region of gas must have in order for self-gravity to overcome pressure and initiate gravitational collapse, potentially leading to star formation. |
| Jellyfish Galaxy | Also known as IC 443, it is a supernova remnant and emission nebula located in the constellation Gemini. |
| Jellyfish Nebula | A supernova remnant located in the constellation Gemini, named for its shape resembling a jellyfish. |
| Jewel Box Cluster | A young open star cluster located in the southern constellation Crux (Southern Cross), known for its colorful and gem-like stars. |
| Jewel Box Galaxy | A barred spiral galaxy, also known as NGC 4755, found in the constellation Centaurus, resembling a sparkling gem in the sky. |
| Jewel Box Nebula | A planetary nebula in the constellation Crux, known for its intricate and colorful appearance. |
| Jitter | Small, rapid, and unpredictable movements or vibrations that can affect the stability and accuracy of astronomical observations. |
| Jittery Stars | Stars that appear to twinkle or shimmer due to the Earth’s atmosphere causing fluctuations in the light passing through it. |
| Job’s Coffin | An asterism in the constellation Scorpius, formed by a pattern of stars resembling a coffin. |
| Johnson Filter | A type of optical filter used in astronomy to isolate specific wavelengths of light, often named after their inventor, Lyman Spitzer Jr. |
| Jovian Moon | A moon that orbits one of the gas giant planets, such as Jupiter’s moons Io, Europa, Ganymede, and Callisto. |
| Jovian Planets | The gas giant planets of the outer solar system, including Jupiter and Saturn. |
| Jovian System | The entire collection of a gas giant planet, its rings, and its moons, along with their interactions and dynamics. |
| Joy Crater | A crater on Mars named in honor of the Mars rovers, Spirit and Opportunity, and their contributions to planetary science. |
| Julian Date | A continuous count of days since noon on January 1, 4713 BCE (Julian calendar), often used in astronomical calculations. |
| Julian Period | A long period of time, approximately 7980 years, often used in astronomy for calendrical calculations and conversions. |
| Jump Drive | A hypothetical propulsion system often depicted in science fiction, allowing spacecraft to instantly travel vast distances in space. |
| Jumping Craters | A phenomenon observed on some celestial bodies where craters appear to overlap or jump over one another due to impacts at different times. |
| Junko | A proposed name for a hypothetical planet beyond the orbit of Pluto, suggested as part of the naming contest for new dwarf planets. |
| Juno | A NASA spacecraft that is studying the planet Jupiter, designed to understand its composition, gravity field, magnetic field, and polar magnetosphere. |
| Jupiter | The largest planet in the solar system, known for its massive size, numerous moons, and distinct bands of clouds. |
| Jupiter Trojans | Groups of asteroids that share Jupiter’s orbit, located at stable points ahead of and behind the planet in its path around the Sun. |
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