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  ✦

Time-Lapse Auroras Over Norway

December 29, 2013
© Terje S�rgjerd; Music: Gladiator Soundtrack: Now we are Free
Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case in 2011 March when one of the largest auroral displays in recent years appeared over northern locations like the border between Norway and Russia. Pictured in the above time-lapse movie, auroras flow over snow covered landscapes, trees, clouds, mountains and lakes found near Kirkenes, Norway. Many times the auroras are green, as high energy particles strike the Earth's atmosphere, causing the air to glow as electrons resettle into their oxygen hosts. Other colors are occasionally noticeable as atmospheric nitrogen also becomes affected. In later sequences the Moon and rising stars are also visible. With the Sun currently hovering near its time of maximum activity, there may be many opportunities to see similarly spectacular auroras personally, even from areas much closer to the equator. Free lecture: APOD editor to speak in NYC on Jan. 3

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
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