Five Planets and the Moon over Australia
16.08.2016

It is not a coincidence that planets line up. That's because all of the planets orbit the Sun in (nearly) a single sheet called the plane of the ecliptic. When viewed from inside that plane -- as Earth dwellers are likely to do -- the planets all appear confined to a single band.

Supermoon and Space Station
14.11.2016

What are those specks in front of the Moon? They are silhouettes of the International Space Station (ISS). Using careful planning and split-second timing, a meticulous lunar photographer captured ten images of the ISS passing in front of last month's full moon.

Venus and Mars: Passing in the Night
29.03.2022

When two planets pass on the night sky, they can usually be seen near each other for a week or more. In the case of this planetary conjunction, Venus and Mars passed within 4 degrees of each other earlier this month.

Mars Rises above the Lunar Limb
9.12.2022

On the night of December 7 Mars wandered near the Full Moon. In fact the Red Planet was occulted, passing behind the Moon, when viewed from locations across Europe and North America. About...

APOD: 2025 February 11 Б The Spider and the Fly
11.02.2025

Will the spider ever catch the fly? Not if both are large emission nebulas toward the constellation of the Charioteer (Auriga). The spider-shaped gas cloud in the image center is actually an emission nebula...

APOD: 2025 November 9 Б Road to the Galactic Center
9.11.2025

Does the road to our galaxy's center go through Monument Valley? It doesn't have to, but if your road does -- take a picture. In this case, the road is US Route 163 and iconic buttes on the Navajo National Reservation populate the horizon.

APOD: 2025 December 22 Б Sunset Solstice over Stonehenge
22.12.2025

Yesterday the Sun reached its southernmost point in planet Earth's sky. Called a solstice, many cultures mark yesterday's date as a change of seasons -- from autumn to winter in Earth's Northern Hemisphere and from spring to summer in Earth's Southern Hemisphere.

A Double Ringed Basin on Mercury
7.10.2009

What created the internal second ring of this double ringed basin on Mercury? No one is sure. The unusual feature spans 160 kilometers and was imaged during the robotic MESSENGER spacecraft's swing past our Solar System's innermost planet last week.

The Vertical Magnetic Field of NGC 5775
27.01.2021

How far do magnetic fields extend up and out of spiral galaxies? For decades astronomers knew only that some spiral galaxies had magnetic fields. However, after NRAO's Very Large Array (VLA) radio telescope...

APOD: 2024 July 23 Б The Crab Nebula from Visible to X Ray
23.07.2024

What powers the Crab Nebula? A city-sized magnetized neutron star spinning around 30 times a second. Known as the Crab Pulsar, it is the bright spot in the center of the gaseous swirl at the nebula's core.