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Editors of EarthSky

Solstices and equinoxes in a video from space

See how sunlight falls on Earth's surface during the solstices and equinoxes, and get a better understanding of why Earth's tilt causes the seasons.

Why does Earth have 4 seasons every year?

Some assume our planet's changing distance from the sun causes the four seasons. But it's actually the tilt of the Earth's axis.

Venus brightest in morning sky September 19, 2023

When is Venus brightest? It'll be brightest in the morning sky around September 19, 2023. Venus will not be this bright again until February and April of 2025.

Meteor shower guide: Up next October Draconids and Orionids

We've got several more meteor showers this year. Next up are the Draconids and Orionids in October, with Taurids mixed in. Your 2023 meteor shower guide here.

How many stars can you see on a moonless night?

Have you ever wondered how many stars are visible on a given night? It all depends on how dark your sky is, what your age is, and other limiting factors.

Cassiopeia ascends in September and October

Cassiopeia the Queen is an easy-to-find constellation. It has the shape of a W or M. Look in the north-northeast sky on September and October evenings.

Mercury – up before sunrise – greatest elongation September 22

Mercury reaches its greatest elongation - greatest distance from the sunrise - on September 22. Look east at dawn. It'll brighten through early October.

Catch the Winter Circle and the moon before dawn

The majestic Winter Circle isn't a constellation, it's an asterism. It's a giant circle - or hexagon - figure made of bright stars from several constellations.

Zodiacal light, or false dawn: Start watching now

The zodiacal light is an eerie light extending up from the horizon. The months around the September equinox are a good time to see it. How to see them, here.

Sapphire: September birthstone comes in many colors

Sapphire, the September birthstone, is typically blue, the color caused by small amounts of titanium and iron in the crystal structure.