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 I 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 |
|---|---|
| Iapetus | One of Saturn’s moons, known for its stark brightness contrast between its leading and trailing hemispheres. |
| Icarus (1566 Icarus) | A near-Earth asteroid with an exceptionally small perihelion distance, making it one of the closest known asteroids to the Sun. |
| Ice Giant | A type of gas giant planet, like Uranus and Neptune, primarily composed of elements such as hydrogen, helium, and water in various forms. |
| Impact Basin | A large, circular depression on a planet or moon’s surface resulting from the impact of a massive celestial body, often forming early in their history. |
| Impact Event | The occurrence of a collision between a celestial body (e.g., asteroid, comet) and another object, such as a planet or moon. |
| Indus | A southern constellation representing the Indian, introduced by Dutch astronomer Petrus Plancius in the late 16th century. |
| Infrared Astronomy | The branch of astronomy focused on observing and studying celestial objects and phenomena using infrared radiation. |
| Intergalactic Medium | The sparse and tenuous matter that exists between galaxies in the vast expanse of space. |
| International Space Station (ISS) | A habitable space station that orbits Earth and serves as a laboratory and living space for astronauts from various countries. |
| Interplanetary Dust | Microscopic particles of dust that exist in the space between planets, often originating from comets or asteroids. |
| Interstellar | The space between stars within a galaxy. |
| Interstellar Medium | The matter and gases that exist in the space between stars within a galaxy, composed of gas, dust, and cosmic rays. |
| Invariable Plane | The plane defined by the angular momentum vector of the Solar System, which remains nearly constant despite the gravitational influences of the planets. |
| Inverse Compton Scattering | A process in which a high-energy photon gains energy when it interacts with a lower-energy electron, commonly observed in astrophysical environments. |
| Inverse Doppler Effect | The apparent decrease in frequency of electromagnetic waves emitted by a receding source, observed when an object is moving away from an observer. |
| Inverse Square Law | A physical law stating that the intensity of a physical quantity (such as light or gravity) decreases with the square of the distance from the source. |
| Io | One of Jupiter’s largest moons, known for its active volcanism and colorful surface features. |
| Io Plasma Torus | A region of charged particles surrounding Jupiter and its moon Io, influenced by their magnetic interactions and volcanic activity. |
| Io Torus | A doughnut-shaped region of charged particles, mainly sulfur and oxygen ions, surrounding Jupiter and its moon Io. |
| Ionosphere | A region of Earth’s upper atmosphere where ions and electrons are present, important for radio wave propagation and satellite communication. |
| Irregular Galaxy | A galaxy with a non-symmetrical or irregular shape, often lacking defined spiral or elliptical structures. |
| Isotope | Variants of a chemical element with the same number of protons but a different number of neutrons, resulting in different atomic masses. |
| Izar (Epsilon Bootes) | A double star system in the constellation Bootes, easily distinguishable as a binary star through a telescope. |
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