Solar System

Hot Jupiter superrotation

Hot Jupiter superrotation is the atmospheric regime in which equatorial winds on tidally locked hot Jupiters exceed the planet's rotation, displacing the dayside hotspot eastward of the star-facing point.

Hycean planet

A Hycean planet, or Hycean world, is a proposed class of habitable sub-Neptune exoplanet with a water ocean under a hydrogen-rich atmosphere, theorized in 2021.

Iapetus (moon)

Iapetus is the third-largest moon of Saturn, a cratered icy body with one hemisphere dark and one bright and an equatorial ridge up to 20 km high.

Icarus (journal)

Icarus, also known as the International Journal of Solar System Studies, is a peer-reviewed journal of Solar System research, first published by Academic Press in 1962.

Ice giant

An ice giant is a giant planet composed mainly of water, ammonia, and methane rather than hydrogen and helium; Uranus and Neptune are the Solar System's two members.

Ilmarë (moon)

Ilmarë is the large satellite of the trans-Neptunian object Varda, discovered in 2009 in Hubble images and named in 2014 after a handmaid of Varda in Tolkien's mythology.

Immanuel Velikovsky (Иммануил Великовский)

Immanuel Velikovsky (Иммануил Великовский, 1895–1979) was a Russian-born psychiatrist and psychoanalyst whose 1950 bestseller Worlds in Collision claimed recent planetary catastrophes, igniting fierce scientific controversy.

Impact event

An impact event, also called an Earth impact, is a collision between an asteroid or comet and Earth or another body, leaving a crater or causing an airburst.

Indian Institute of Space Science and Technology

The Indian Institute of Space Science and Technology (IIST) is a deemed university in Thiruvananthapuram, Kerala, founded by ISRO and inaugurated in 2007 as Asia's first space-dedicated university.

Inner main belt

The inner main belt is the innermost zone of the main asteroid belt, between about 2.05 and 2.5 au, dominated by Vesta and a major source of meteorites.

Internal structure of Jupiter

The internal structure of Jupiter is the layered arrangement of hydrogen, helium, and heavier elements inside the largest planet, inferred indirectly from gravity and magnetic-field measurements.

Internal structure of the Moon

The internal structure of the Moon is its division into a crust, a silicate mantle 1,100 to 1,300 km thick, and a core of 300 to 400 km radius.

International Asteroid Warning Network

The International Asteroid Warning Network (IAWN) is a UN-endorsed, NASA-coordinated collaboration of asteroid astronomers, created in 2013 after the Chelyabinsk airburst, that tracks hazardous near-Earth objects and issues impact warnings.

Io (moon)

Io, also known as Jupiter I, is the innermost of Jupiter's Galilean moons and the most volcanically active world in the solar system, with about 400 active volcanoes.

Io (Ἰώ)

Io is Jupiter's innermost Galilean moon, slightly larger than Earth's Moon, and the most volcanically active body in the Solar System, with roughly 400 active volcanoes.

Iron and nickel vapor in comets

Iron and nickel vapor in comets refers to neutral iron and nickel atoms found in cometary atmospheres, first widely detected in about twenty comets with the VLT in 2021.

J002E3

J002E3 is a near-Earth object discovered by Bill Yeung in 2002, later identified as the likely Saturn V third stage that launched Apollo 12 in 1969.

Jacobi integral

The Jacobi integral, also called the Jacobi constant, is the only known conserved quantity of the circular restricted three-body problem, representing energy in the frame rotating with the two primaries.

January 2018 lunar eclipse

The January 2018 lunar eclipse, popularly called the super blue blood moon, was a total lunar eclipse on January 31, 2018, combining a supermoon, a blue moon, and totality.

John Carter of Mars

John Carter of Mars is the hero of Edgar Rice Burroughs's science fiction series, beginning with A Princess of Mars in 1912 and spanning eleven books.

Journal of Geophysical Research

The Journal of Geophysical Research is a family of peer-reviewed geoscience journals published by the American Geophysical Union, tracing its lineage to Terrestrial Magnetism, founded in 1896.

JPL Horizons On-Line Ephemeris System

JPL Horizons On-Line Ephemeris System is a web service of NASA's Jet Propulsion Laboratory that produces accurate, customizable ephemerides for planets, moons, asteroids, comets, and spacecraft.

JPL Small-Body Database

The JPL Small-Body Database (SBDB) is a NASA database maintained by the Jet Propulsion Laboratory covering orbital data for nearly one million known asteroids and comets.

July 2018 lunar eclipse

The July 2018 lunar eclipse was a total lunar eclipse on 27–28 July 2018, the longest total lunar eclipse of the 21st century at 1 hour 43 minutes.

Jupiter

Jupiter is the fifth planet from the Sun and the largest in the solar system, a gas giant with 115 known moons and a day of 9.9 hours.

Jupiter's dilute core

Jupiter's dilute core is an interior structure in which heavy elements are dissolved into the planet's hydrogen and helium envelope, revealed by NASA's Juno spacecraft.

Jupiter's polar cyclones

Jupiter's polar cyclones are clusters of large, long-lived storms at the planet's poles: eight circumpolar cyclones in the north and five in the south, discovered by NASA's Juno spacecraft in 2016.

Kamoʻoalewa

Kamoʻoalewa, minor planet 469219, is a roughly 18-meter near-Earth asteroid in a quasi-satellite orbit around Earth, discovered in 2016 in Hawaii and targeted by China's Tianwen-2 sample-return mission.

Kepler-1625b I

Kepler-1625b I is a candidate exomoon of the Jupiter-sized planet Kepler-1625b, 8,000 light-years away in Cygnus, claimed in 2018 and disputed since, with no moon confirmed.