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

Phantoms in Cassiopeia

October 26, 2024
Credit: Christophe Vergnes , Hervรฉ Laur
See this entry on NASA's APOD โ†’
These brightly outlined flowing shapes look ghostly on a cosmic scale. A telescopic view toward the constellation Cassiopeia , the colorful skyscape features the swept-back, comet-shaped clouds IC 59 (left) and IC 63. About 600 light-years distant, the clouds aren't actually ghosts. They are slowly disappearing though, under the influence of energetic radiation from hot, luminous star gamma Cas. Gamma Cas is physically located only 3 to 4 light-years from the nebulae and lies just above the right edge of the frame. Slightly closer to gamma Cas, IC 63 is dominated by red H-alpha light emitted as hydrogen atoms ionized by the hot star's ultraviolet radiation recombine with electrons. Farther from the star, IC 59 shows less H-alpha emission but more of the characteristic blue tint of dust reflected star light . The field of view spans over 1 degree or 10 light-years at the estimated distance of the interstellar apparitions .

Customized Star Charts Coming 1st Quarter 2027

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โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
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