Comet NEOWISE

Comets

Comet NEOWISE Delights at Dawn

Skywatchers are treated to a naked-eye comet as NEOWISE emerges into the the dawn sky.

Asteroid illustration

Solar System

Exploring Links Between Nearby Asteroids

In preparation for the launch of Destiny+, a new study reveals that two near-Earth asteroids may share the same parent.

Chaotic, Jupiter-like orbit

Solar System

Jupiter Has Trapped a Comet in a Bizarre Orbit

Jupiter has captured an icy comet from the outer solar system. The comet's bizarre orbit will bring it back for another super-close pass in 2063.

Celestial News & Events

Sky Surprises: New Comet ASASSN1, Nova in Scutum, and Supernova in Pisces!

Between the discovery of the new comet ASASSN1 and two stellar explosions, there's a lot happening in the sky this week. Take your telescope out and see what all the excitement's about.

Finder Chart Comet 45P/

Comets

Bright Prospects for Comets in 2017

Comet lovers have much to look forward to in the new year with six potential bright binocular comets and at least two others for modest backyard telescopes.

Blue Q-tip

Comets

Catalina Comet Sails Into Northern Skies

Comet Catalina returns this month with naked-eye potential. Follow its every move with our guide and maps.

Astronomy Questions & Answers

Asteroids: What Are They and Where Do They Come From?

Asteroids are rocky objects leftover from the solar system's formation, found primarily in the asteroid belt, a region of the solar system in between the orbits of Mars and Jupiter.

Comet ISON (C/2012 S1)

Astronomy Questions & Answers

Comets: What Are They? Where Do They Come From?

Comets are suspected to be remnants of planet formation in the solar system about 4.6 billion years ago and primarily originate in the Kuiper Belt and the Oort Cloud.

Astronomy Questions & Answers

Why do comets have tails?

Comets develop tails as they approach perihelion—the place in their orbits when they are closest to the sun. The sun’s heat causes some of the material in a comet to vaporize, which in turn releases dust particles that were trapped in the ice.

Science-based Q&A

If asteroid 99942 Apophis ever strikes Earth, how big would the crater be?

If the near-Earth asteroid 99942 Apophis ever strikes Earth, how big would the crater be? Apophis (formerly 2004 MN4) ranks at the top of the worrisome-asteroid list. On April 13, 2029 (yes, that will be a Friday the 13th), it will pass only 30,000 kilometers (18,600 miles) from Earth’s surface…

Astronomy Questions & Answers

How large an asteroid could a person jump off?

How large an asteroid could a person jump off? This interesting question goes back to 1952 or even earlier. It turns out that the asteroid must be no bigger than 3.9 v(ρe / ρ) kilometers in diameter, where ρ is the asteroid’s density and ρe is that of Earth in…

Comet Tempel 1

Hobby-based Q&A

What is the most distant human-caused event that’s been easily verifiable with ordinary optics?

Like other amateurs, I observed the brightening of Comet Tempel 1 after it was hit by Deep Impact on July 4, 2005. Was this the most distant human-caused event that’s been easily verifiable with ordinary optics? (I used my 12-inch Dobsonian reflector.) Yes, we think so. The Deep Impact collision…

Tim Hunter and his telescope

Astronomy Questions & Answers

How Can Amateurs Find Asteroids?

In a 1996 article titled “Hunting Asteroids,” you said a dedicated amateur could discover an asteroid on almost any night using a CCD-equipped 8-inch telescope. Is that still true today? It was easier for backyard observers to discover asteroids a few years ago. Today, massive professional surveys such as LINEAR,…

Comet Halley

Hobby-based Q&A

Will it ever be possible to observe Halley's Comet around its entire orbit?

With larger and larger telescopes being built, will it ever be possible to observe Halley's Comet around its entire orbit? It's already being done! The most recent observations of Halley were made on March 6, 7, and 8, 2003, by Belgian astronomer Olivier Hainaut and his colleagues, who acquired simultaneous…

Apophis and Earth in 2029

Astronomy Questions & Answers

Will asteroid 99942 Apophis eclipse the Moon when it passes by?

When I heard that a 300-meter asteroid will approach Earth at a distance of only 18,000 miles in 2029, I figured it was time to break out the old slide rule. Wouldn't an object that big and close be able to eclipse the Moon, if it should pass in front…

Comet Holmes

Astronomy Questions & Answers

Does a comet's tail (or lack there-of) tell us what direction it's heading?

When Comet Holmes was heading away from Earth, we on Earth didn't see an angled view of the comet's tail. Was it tailless because of its motion? That is, would a comet also appear tailless if it were approaching, with Earth right in its path? It's impossible to tell where…

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