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  ✦

Eclipse Over New York

November 4, 2013
© Chris Cook
A sunrise over New York City rarely looks like this. Yesterday, however, the Sun rose partly eclipsed by the Moon as seen from much of the eastern North American and northern South America. Simultaneously, much of Africa, already well into daytime, saw the eclipse from beginning to end. The eclipse was unusual in that it was a hybrid -- parts of the Earth saw the Moon as too angularly small to cover the whole Sun, and so at maximum coverage left the Sun surrounded by a ring a fire, while other parts of the Earth saw the Moon as large enough to cover the entire Sun, and so at maximum coverage witnessed a total solar eclipse. Slight changes in the angular size of the Moon as seen from the Earth's surface are caused by the non-flatness of the Earth and the ellipticity of the Moon's orbit. Pictured above, the famous Empire State Building in New York City is seen to the left of the partially eclipsed Sun, adorned with scenic clouds. The next solar eclipse visible from New York City -- a very slight eclipse -- will occur during the sunset of 2014 October 23. Growing Gallery: See great eclipse pictures

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
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