Mercurys Sodium Tail
3.05.2022

That's no comet. Below the Pleiades star cluster is actually a planet: Mercury. Long exposures of our Solar System's innermost planet may reveal something unexpected: a tail. Mercury's thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun.

Circling the Sun
13.01.2024

Earth's orbit around the Sun is not a circle, it's an ellipse. The point along its elliptical orbit where our fair planet is closest to the Sun is called perihelion. This year...

Southwest Mercury
13.02.2000

The planet Mercury resembles a moon. Mercury's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron.

Two Views of Earth
23.07.2013

In a cross-Solar System interplanetary first, our Earth was photographed during the same day from both Mercury and Saturn. Pictured on the left, Earth is the pale blue dot just below the rings of Saturn, as captured by the robotic Cassini spacecraft now the gas giant.

Mercurys Transit: An Unusual Spot on the Sun
24.08.2014

What's that dot on the Sun? If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse that occurred in 2006. Usually it is the Earth's Moon that eclipses the Sun. This time, the planet Mercury took a turn.

Mars Engulfed
17.06.2018

What's happened to Mars? In 2001, Mars underwent a tremendous planet-wide dust storm -- one of the largest ever recorded from Earth. To show the extent, these two Hubble Space Telescope storm watch images from late June and early September (2001) offer dramatically contrasting views of the martian surface.

Venus Unveiled
10.02.2019

What does Venus look like beneath its thick clouds? These clouds keep the planet's surface hidden from even the powerful telescopic eyes of Earth-bound astronomers. In the early 1990s, though, using imaging radar...

September Sunrise Shadows
24.09.2022

The defining astronomical moment for this September's equinox was on Friday, September 23, 2022 at 01:03 UTC, when the Sun crossed the celestial equator moving south in its yearly journey through planet Earth's sky.

APOD: 2023 May 24 Б Observatory Aligned with Moon Occulting Jupiter
24.05.2023

Sometimes we witness the Moon moving directly in front of -- called occulting -- one of the planets in our Solar System. Earlier this month that planet was Jupiter. Captured here was the moment when Jupiter re-appeared from behind the surface of our Moon.

APOD: 2026 February 1 Б Galle: Happy Face Crater on Mars
1.02.2026

Mars has put on a happy face. The Martian crater Galle is famous because it has internal markings that make it look like a face that is both smiling and winking. These markings were originally discovered in the 1970s in pictures taken by the Viking Orbiter.