Resources and Education

Here you’ll find the resources you need to get started observing, photographing, and more — your essential introduction to astronomy. Find out which telescopes are best for starting out, the basics of using a star wheel, and what terms you need to know.

And that’s just to get your started. As you delve into the hobby, you’ll want to start using our interactive observing tools and star charts, and maybe you’ll even try your hand at astrophotography. Whatever you try, good luck and clear skies!

Comet ISON (C/2012 S1)

What is a comet? Where do comets come from?

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.

Comet Hale-Bopp.Fred Espenak, NASA GSFC

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.

Earth and Sun size comparison.ESA & NASA

How big is the Sun?

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.

perseids_meteor_shower

What is a meteor shower?

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.

Andreas Cellarius's illustration of the Ptolemaic System (17th century), which shows the solar system and signs of the zodiac with the Earth at the center.J. van Loon, National Library of Australia

Astrology vs Astronomy: What’s the difference?

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.

New Comet Machholz

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.