The Rhythm of the Spheres

Reading the Night Sky

Wandering in Astronomy

The night sky is the oldest pattern of man, and every culture reads it differently. The stars above keep silent time, moving to a rhythm we are just now beginning to understand. Astronomy is where math, science, art, music, and words meet in a wondrous collision. In this section of our site, learn the basics of astronomy: from how a star chart is made, to projections and art that map the night sky, to how an astrolabe works just like it did thousands of years ago. Watch the North Star shift across centuries, explore how one sky has been mapped by many traditions, read what happened on this day in space, and see tonight’s moon for your location.

Map the Stars

The math behind star charts, with a projection explorer and a working astrolabe.

The Moving Sky

How the sky shifts across centuries, with a precession clock you can run.

The Traditions

One sky reads many ways, with a same-sky overlay of the world’s constellations.

This Day in the Stars

The sky’s events, discoveries, and lore tied to today’s date.

The Moon Tonight

Its phase and face, drawn live for where you’re standing.

✦  Astronomy Picture of the Day  ✦

APOD Turns Eighteen

June 16, 2013
© Wang Letian
The first APOD appeared eighteen years ago today, on 1995 June 16. Although garnering only 14 pageviews on that day, we are proud to estimate that APOD has now served over one billion space-related images over the past eighteen years. That early beginning, along with a nearly unchanging format, has allowed APOD to be a consistent and familiar site on a web frequently filled with change. Many people don't know, though, that APOD is now translated daily into many major languages. We again thank our readers, astrophotographers, and NASA for their continued support, but ask that any potentially congratulatory e-mail go this year to the volunteers all around the world who translate APOD's captions daily, many times with considerable effort. Some APOD images are featured in the above spectacular collage visualizing APOD as a classic film reel, submitted by an APOD enthusiast skilled in digital image manipulation. How many APOD images can you identify? APOD is also available in: Arabic, Bahasa Indonesian, Catalan, Chinese, Chinese, Czech, Dutch, Farsi, Farsi, Galego, German, French, Hebrew, Japanese, Polish, Portuguese, Romanian, Russian, Slovenian, Spanish, Thai, or Turkish

Customized Star Charts Coming 1st Quarter 2027

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
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