EarthSky | Earth, Space, Sun, Human, Tonight

There may be less water ice on the moon than we thought

September 21, 2023

On the equinox, are day and night equal that day?

Day and night are mostly equal on the equinox. There's a bit more daylight because the sun is a disk, not a point, and Earth’s atmosphere refracts sunlight.

Bruce McClure

September 21, 2023

Earth

Florida’s bleached corals get emergency sunshades

Scientists constructed sunshades over bleached corals in two of Florida's national parks in an effort to protect them from further damage.

Kelly Kizer Whitt

September 21, 2023

Sun

Sun activity is moderate, with an almost-X flare

Sun activity for September 21, 2023, is moderate with an M8 flare. Earth's geomagnetic field has quietened down, but may become active over the next day.

September 21, 2023

Psyche mission to explore priceless asteroid

The Psyche mission will launch on October 5, 2023, on a mission to explore the metal-rich asteroid Psyche. Learn more about the mission and asteroid here.

Kelly Kizer Whitt

September 20, 2023

Astronomy Essentials

Visible planets and night sky for September

Mars is going into the sun. Jupiter and Saturn are evening objects. Morning planets are Venus, Jupiter and Mercury. Visible planets, here.

September 20, 2023

Ants, little but tough: Lifeform of the week

Ants are common insects with unique capabilities. They can harvest, herd, milk, and build amazingly complex and stable underground cities.

Cristina Ortiz

September 20, 2023

Tonight

Equinox sun rises due east and sets due west

The 2023 September equinox occurs on September 23 at 6:50 UTC (1:50 a.m. CDT). At the equinox, the sun rises and sets due east and due west.

Bruce McClure

September 20, 2023

Space

Closest black holes yet in famous Hyades star cluster?

Researchers in Europe say that they may have found the closest known black holes to Earth, in the Hyades open star cluster 150 light-years away.

Paul Scott Anderson

September 19, 2023

Tonight

Why can’t I find the Big Dipper in September?

Use the famous Big Dipper to find Polaris, the North Star. In September, the Big Dipper is in the northwest in the evening. But watch for it soon!

Larry Sessions

September 19, 2023

Astronomy Essentials

Year’s fastest sunsets happen around equinoxes

The year's fastest sunsets are at the equinoxes, and the slowest are at the solstices. We're talking about how long it takes the sun to sink below the horizon.

Bruce McClure

September 19, 2023