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Spacecraft and Space Missions

NASA Launches Lucy Mission to Trojan Asteroids

NASA’s ambitious Lucy mission has launched to explore Jupiter's Trojan asteroids, pristine examples of the solar system's early years.

2021 PH27

Solar System

Astronomers Discover Asteroid that Flies Close to the Sun

Newly discovered asteroid 2021 PH27 orbits the Sun in just 113 days.

Solar System

Two Extremely Red Asteroids Discovered Far from Home

Astronomers have discovered the two reddest objects in the asteroid belt, and their origin story might tell us more about planet formation.

Orbit of Comet 2014 UN271

Solar System

Giant Oort Cloud Comet Lights Up in the Outer Solar System

Astronomers have discovered a new comet coming from the Oort Cloud — and it appears to be a big one.


Solar System

Iron Volcanos: Maybe Not Science Fiction After All

A new study of asteroid 16 Psyche suggests that ferrovolcanism, volcanoes that spewed molten iron, might have been present on this object.


Celestial Objects to Observe

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.

Explore the Night with Bob King

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/

Explore the Night with Bob King

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

Explore the Night with Bob King

Catalina Comet Sails Into Northern Skies

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

Science-based Q&A

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.

Science-based Q&A

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.

Astronomy Questions & Answers

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

Hobby-based Q&A

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

Science-based Q&A

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…