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.
Like asteroids, comets are suspected to be remnants of planet formation in the solar system about 4.6 billion years ago. But while asteroids are generally comprised of rock and metal, comets are more akin dirty snowballs. Comets primarily originate in the Kuiper Belt and the Oort Cloud.
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.
The Sun is more than 330,000 times as massive than the Earth. It has a diameter of nearly 1.4 million kilometers (865,000 miles), and its volume could enclose about 1.3 million Earths.
There are eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
The Sun’s outer atmosphere, the corona, is the source of the solar wind, a steady outflow of charged particles from the Sun.
When it comes to both mass and volume, Jupiter is the largest planet in the solar system, while Mercury is the smallest.
Meteor showers occur when Earth passes through a stream of meteoric material. The brief streaks of luminescence we call meteors are caused by meteoroids burning up as they pass through the atmosphere.
The practices of astrology and astronomy have common roots, but they have evolved into two separate fields. Astronomy studies positions, motions, and properties of celestial objects. Astrology attempts to study how those positions, motions, and properties affect people and events on Earth.
Radio astronomy is the study of the universe through analysis of very long-wavelength emission from celestial objects.
Toddlers can gain a great deal from star parties, more than we might think possible. Here are some further resources for engaging youngsters at your next event.
Look a little deeper into the summer sky with our new e-book, Summer Deep-Sky Observing. We'll have you happily busy at your telescope all season long!
When a meteor shower is coming up, have you thought of trying your hand at meteor photography? Here are some techniques to help you on your way.
Download our free guide to the heavens and learn how to observe all the wonders overhead.
A nova visible in good binoculars was spotted July 7, 2012, by observers in Japan.
Both Pluto and the star are 14th magnitude, but observers with big telescopes and sufficient video capability should try to record this important event.
Watch S&T senior editor Alan MacRobert show and explain how to use star charts and planispheres (star wheels).
Here are some celestial photos taken with Celestron's new flagship telescope, the 14-inch EdgeHD.
On November 3, 2010, two amateurs in Japan discovered an 8th-magnitude comet visually. It's visible in binoculars.
For anyone in a 25-mile-wide path right across Los Angeles, a bright star in Ophiuchus will wink off for several seconds in the predawn hours of April 6, 2010.
California's comet-hunting veteran Don Machholz bagged his 11th discovery on March 23 and 26, 2010. It's a faint diffuse comet, low in the morning sky.
Here are hyperlinks to many websites that can help you forecast the astronomical observing conditions for next few nights — or longer.
Japanese amateur Koichi Itagaki, of recent comet fame, has just discovered a nova near Rigel on November 25, 2009.
Have you ever felt that you ought to be able to see more in the night sky using just your unaided eyes? You may need nothing more than a new pair of eyeglasses.
On March 26, 2009, Korean amateur Dae-am Yi caught the small, greenish glow of a new comet with his Canon camera.