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.
Milky Way Above Easter Island
Customized Star Charts Coming 1st Quarter 2027
We respect your privacy. Unsubscribe at any time.
Superdense neutron star caught feeding on a blue hypergiant's stellar wind
Using data from the Japan–led XRISM (X-ray Imaging and Spectroscopy Mission) observatory, astronomers have directly observed a giant star's outflow, called a stellar wind, being captured by its c…
ReadBy any other name: NGC 1269 or NGC 1291?
The galaxy you see here has an identity crisis. Scottish astronomer James Dunlop discovered it in 1826, and John Dreyer included it as the 1,291st entry in his New General Catalogue. Ten years afte…
Read2026 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…
ReadResearchers measure the environment where the first supermassive black holes formed
When the James Webb Space Telescope pointed its powerful instruments toward the early universe, scientists were surprised by what it found. At high-redshift (z) values, corresponding to less than 1…
ReadSept. 21, 1974: Mariner 10 flies by Mercury
On Sept. 21, 1974, the Mariner 10 spacecraft made its second flyby of Mercury, passing by the surface at a distance of just under 30,000 miles (48,000 kilometers). Launched Nov. 3, 1973, Mariner 10…
ReadVisible planets and night sky guide for September
Visible planets and night sky guide: This is magnificent week! Don't miss the equinox, the full Harvest Moon, and Saturn and Venus in the evening sky.
ReadSun news: Promising sunspot group AR4534 is growing
Sun news September 21, 2026: The sun is taking a breather, but sunspot region AR4534 is growing fast and just gained a promising delta complexity.
Read6th batch of Pentagon UAP files: Air Force talk and more
The 6th batch of the Pentagon UAP files has just been released. Read about a U.S. Air Force talk on UAP from 1952, see more videos and more.
ReadHubble spots an out-of-sync galaxy
Though the spiral galaxy in this new image from the NASA/ESA Hubble Space Telescope seems serene, it hides a chaotic secret. This galaxy is NGC 4698, and it lies about 55 million light-years away i…
Read