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.

โœฆ  Astronomy Picture of the Day  โœฆ

Seven Sisters versus California

April 5, 2022
Credit: Neven Krcmarek
See this entry on NASA's APOD โ†’
On the upper right, dressed in blue, is the Pleiades . Also known as the Seven Sisters and M45 , the Pleiades is one of the brightest and most easily visible open clusters on the sky. The Pleiades contains over 3,000 stars, is about 400 light years away, and only 13 light years across. Surrounding the stars is a spectacular blue reflection nebula made of fine dust . A common legend is that one of the brighter stars faded since the cluster was named. On the lower left, shining in red, is the California Nebula . Named for its shape, the California Nebula is much dimmer and hence harder to see than the Pleiades . Also known as NGC 1499 , this mass of red glowing hydrogen gas is about 1,500 light years away. Although about 25 full moons could fit between them , the featured wide angle, deep field image composite has captured them both . A careful inspection of the deep image will also reveal the star forming region IC 348 and the molecular cloud LBN 777 (the Baby Eagle Nebula).

Customized Star Charts Coming 1st Quarter 2027

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โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
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