EarthSky - Earth, Space, Human World, Tonight

In August 2021, at nightfall, watch for the visible planets. Venus descends in the west as Jupiter and Saturn ascend in the east. Mercury and Mars hide in evening twilight.

Bruce McClure

Deborah Byrd

July 31, 2021

Space

Neutron-star mountains are tiny (but you can’t climb ’em)

Researchers in the UK have found that neutron-star mountains are less than a millimeter tall. These dense, dead stars are nearly perfectly smooth spheres.

Paul Scott Anderson

July 31, 2021

Brightest Stars

Exquisite Albireo, a much-loved double star

Albireo, in the constellation Cygnus the Swan, is a favorite among stargazers. Through a small telescope, it appears as a stunning gold star with a dimmer blue companion.

Bruce McClure

Shireen Gonzaga

July 31, 2021

Moon Phases

Moon phases for meteor watching in 2021

Use our calendar to find out what phase the moon is in. Dates closest to new moon provide the darkest skies and the best opportunities to spot meteors.

EarthSky

July 30, 2021

Human World

Space

A Dyson sphere harvests the energy of stars

Dyson spheres are named after inventor Freeman J. Dyson. A Dyson sphere is a megastructures that civilizations could use to harness the power of stars.

Deborah Byrd

July 30, 2021

Space

Jupiter X-ray aurora mystery solved, after 40 years

A Jupiter X-ray aurora mystery has perplexed astronomers for decades. Now they think ions responsible for the X-rays "surf" electromagnetic waves into Jupiter's atmosphere.

Lia De La Cruz

July 30, 2021

Astronomy Essentials

Transits of Jupiter’s moons ahead: A triple!

Observers using a good pair of binoculars or a small telescope can see events called transits on Jupiter, when a moon or its shadow passes in front of the giant planet.

Kelly Kizer Whitt

July 30, 2021