Comets - NASA Science
Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets.
What’s Up: October 2024 Skywatching Tips from NASA
Oct 2, 2024 · The comet, known as C/2023 A3, aka Tsuchinshan-ATLAS, is currently speeding through the inner solar system. It passed its closest to the Sun in late September, and will be at its closest to Earth on October 13th.
Comets: Facts - Science@NASA
Comet Facts. In the distant past, people were both awed and alarmed by comets, perceiving them as long-haired stars that appeared in the sky unannounced and unpredictably. Chinese astronomers kept extensive records for centuries, including illustrations of characteristic types of comet tails, times of cometary appearances and disappearances ...
Asteroids, Comets & Meteors - NASA Science
Explore the 3D world of asteroids, comets, and NEOs. Learn about past and future missions, tracking and predicting orbits, and close approaches to Earth.
1P/Halley - Science@NASA
Halley is often called the most famous comet because it marked the first time astronomers understood comets could be repeat visitors to our night skies. Astronomers have now linked the comet’s appearances to observations dating back more than 2,000 years.
What is a Planet? - NASA Science
A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.
Solar System Exploration - NASA Science
Our solar system has one star, eight planets, five officially named dwarf planets, hundreds of moons, thousands of comets, and more than a million asteroids. Get Solar System Facts. Planet Facts. Planet Sizes and Locations. Temperatures Across the Solar System.
About the Planets - Science@NASA
The solar system has eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. There are five officially recognized dwarf planets in our solar system: Ceres, Pluto, Haumea, Makemake, and Eris. 8.
Asteroids, Comets & Meteors Facts - Science@NASA
Many comets, asteroids, and meteors haven't changed much in the 4.6 billion years since they first formed. Their relatively pristine state makes them wonderful storytellers with much to share about conditions in the early solar system.
Hubble Confirms Largest Comet Nucleus Ever Seen
Apr 12, 2022 · NASA’s Hubble Space Telescope has determined the size of the largest icy comet nucleus ever seen by astronomers. The estimated diameter is approximately 80 miles across, making it larger than the state of Rhode Island.