2000年6月7日 · What Are Comets? * Comets are small, fragile, irregularly shaped bodies composed of a mixture of grains and frozen gases. They have highly elliptical orbits that repeatedly bring them very close to the Sun and then swing them deeply into space, often beyond the orbit of Pluto.

2025年1月9日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

Don’t let the name fool you. Our solar system’s small bodies – asteroids, comets, and meteors – pack big surprises. These chunks of rock, ice, and metal are leftovers from the formation of our solar system 4.6 billion years ago.

Discovery. Comet 2P/Encke was first discovered by Pierre F. A. Mechain on Jan. 17, 1786. Other astronomers located this comet in subsequent passages, but these sightings were not defined as the same comet until Johann Franz Encke calculated its orbit.

Halley's Connection to Meteor Showers. Each time Halley returns to the inner solar system its nucleus sprays ice and rock into space. This debris stream results in two weak meteor showers each year: the Eta Aquarids in May and the Orionids in October.

2025年1月9日 · Richard Stember is the father of two boys, an entrepreneur and an avid amateur astronomer. He is the founder of a non-profit organization that arranges donations of telescopes to public schools for use in science education.

2025年1月9日 · NASA’s real-time science encyclopedia of deep space exploration. Our scientists and far-ranging robots explore the wild frontiers of our solar system.

Introduction. Asteroids, sometimes called minor planets, are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago.

The small Kuiper Belt Object called Arrokoth is a contact binary. It was discovered in 2014 by NASA’s New Horizons science team, using the Hubble Space Telescope.

2025年1月9日 · NASA's Deep Dive Planetary Website. Launched in October 1998, the Solar System Exploration website is a real-time, living encyclopedia of the robotic exploration of our solar system.