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

Treble Clef: Unusual X-ray Hot Radio Source

October 19, 2026
Credit: X-ray: NASA/CXC/INAF-IRA/A. Botteon et al.; Infrared: UKIDSS-GPS; Radio: ASTRONLOFAR; Image processing: NASA/CXC/SAO/N. Wolk
See this entry on NASA's APOD โ†’
Explanation : What is Treble Clef? This unusual radio structure extends over 2 million light-years and resembles a common musical symbol -- but has its visible light hidden by our own Milky Way Galaxy. Examined in 2004, the nature of VLSS J0318.9+5755, dubbed Treble Clef, remained unknown. Recent observations by the Chandra X-ray Observatory and eROSITA, however, have led to the hypothesis that the Treble Clef central cloud of charged particles was originally expelled by a supermassive black hole at the center of a galaxy. After the radio emission from those particles faded, they may have been reinvigorated by a shock wave from the collision of two clusters of galaxies. The featured composite image shows radio emission in red, while recently discovered X-rays are shown in blue. Unusual objects like Treble Clef give humanity unexpected clues about how whole clusters of galaxies interact as well as the general evolution of our universe.

Customized Star Charts Coming 1st Quarter 2027

We respect your privacy. Unsubscribe at any time.

โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
Space Oct 29, 2026

Is this our solar systemโ€™s future? Scientists spot disk around dead star

Researchers have discovered a white dwarf surrounded by a debris disk with 2 separate rings. It offers a possible glimpse of our solar system's future.

Read
Earth Oct 29, 2026

The enormous oarfish could inspire new ways to explore the ocean

The giant oarfish has a remarkable fin that could inspire quieter underwater robots and open new possibilities for ocean exploration and conservation.

Read
Human World Oct 29, 2026

Spooky ghost lights: Believe in them if you dare

Ghost lights are strange lights seen over swamps or bogs. Here are some popular places known for ghost lights. Believe in them ... if you dare!

Read
Observing Oct 29, 2026

The Sky Today on Thursday, October 29: Open cluster Collinder 463

Looking for a sky event this week? Check out our full Sky This Week column.  October 28: The Moon hangs with Uranus The W-shaped constellation Cassiopeia is prominent in the northernโ€ฆ

Read
Astronomy Oct 28, 2026

Sun's outer magnetic field mapped in 3D for the first time

A team of researchers has produced the first global, three-dimensional estimates of the sun's magnetic field, including the area beyond the sun's visible edge. This marks a step toward more accuratโ€ฆ

Read
Astronomy Oct 28, 2026

NASA systems engineering team details Habitable Worlds Observatory mission architecture

Finding an Earth-like world beyond the solar system is the holy grail of exoplanet research, and the field has seen remarkable technological advances in detecting and studying exoplanets since the โ€ฆ

Read
Observing Oct 28, 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 sunlโ€ฆ

Read
Robotic Spaceflight Oct 28, 2026

Oct. 28, 1971: The U.K. launches a satellite

The Prospero satellite, which launched on Oct. 28, 1971, holds the distinction of being the first and only British satellite to be launched by a British rocket. (The first British satellite launcheโ€ฆ

Read
Astronomy Oct 27, 2026

Double debris disk orbiting a dead star hints at our solar system's future

Astronomers using the European Southern Observatory's Very Large Telescope (ESO's VLT) have found a rare disk of debris around a dead star that provides a glimpse of what may happen to our solar syโ€ฆ

Read