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  ✦

130 Years of Earth Surface Temperatures

July 31, 2013
How has the surface temperature of Earth been changing? To help find out, Earth scientists collected temperature records from over 1000 weather stations around the globe since 1880, and combined them with modern satellite data. The above movie dramatizes the result showing 130 years of planet-wide temperature changes relative to the local average temperatures in the mid-1900s. In the above global maps, red means warmer and blue means colder. On average, the display demonstrates that the temperature on Earth has increased by nearly one degree Celsius over the past 130 years, and many of the warmest years on record have occurred only recently. Global climate change is of more than passing interest -- it is linked to global weather severity and coastal sea water levels.

Customized Star Charts Coming 1st Quarter 2027

We respect your privacy. Unsubscribe at any time.

✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
Astronomy Sep 9, 2026

Chandra uncovers 'hypersoft X-ray sources' that may solve two astrophysical puzzles

Using NASA's Chandra X-ray Observatory, scientists have discovered a new class of objects behaving unlike any they have seen before. Astronomers suggest these newly spotted objects in other galaxie…

Read
Astronomy Sep 9, 2026

If alien civilizations use hyper-efficient computers, they will have a distinct energy signal we can detect

Love it or hate it, artificial intelligence is likely here to stay. Its ravenous need for computational power has overwhelmed chip manufacturers and power companies alike. While our current AI obse…

Read
Astronomy Sep 9, 2026

Discontinuity and disorder: Explaining the luminosity bump in evolved stars

Toward the end of their lives, low-mass stars undergo an abrupt dip in brightness, also known as the luminosity bump. While the endpoint of this bump is well understood, its onset has remained elus…

Read
Observing Sep 9, 2026

2026 Full Moon calendar: When to see the Full Moon and phases

The phenomenon of a Full Moon arises when our planet, Earth, is precisely sandwiched between the Sun and the Moon. This alignment ensures the entire side of the Moon that faces us gleams under sunl…

Read
Today in the History of Astronomy Sep 9, 2026

Sept. 9, 1892: Edward Emerson Barnard sees Amalthea

When Edward Emerson Barnard peered through the 36-inch refractor at Lick Observatory on Sept. 9, 1892, and spotted Amalthea, it marked the first discovery of a moon of Jupiter in 280 years. Galileo…

Read
Space Sep 9, 2026

Peptides in Venus’ clouds could form life-giving shapes

A new study from MIT shows that peptides in Venus' clouds could survive in the sulfuric acid droplets and fold into the shapes need for biological life.

Read
Earth Sep 9, 2026

Will fall migration 2026 bring a billion bird night?

Will we see a billion bird night during fall migration this year? And get tips on how you can help birds by turning off exterior lights.

Read
Earth Sep 9, 2026

Fall hummingbird migration in progress across North America

The fall hummingbird migration typically lasts from August through October. Spot the birds in every U.S. state and Canadian province as they travel south.

Read
Observing Sep 9, 2026

The Sky Today on Wednesday, September 9: Visualize the ecliptic

Looking for a sky event this week? Check out our full Sky This Week column.  September 8: The Moon joins Jupiter The waning Moon has moved from Cancer to Leo and is nearing the brigh…

Read