SUNSET: 
The Martian Methane Mystery Continues
The most advanced instrument ever sent to Mars to study its atmosphere has failed to find any methane after months of searching.
Curiosity Sees Phobos Transit . . . After Sunset
NASA's Curiosity rover just spied transits of both Martian moons across the face of the Sun — including one that happened after the Sun had set.
New Study Confirms Methane on Mars – But It’s Not Definitive
Independent methane detections in the Martian atmosphere by the Curiosity rover and Mars Express orbiter add confusion to a convoluted story.
Saturn's Rings Built Up Its Tiny, Close-in Moons
A new study of observations from NASA's Cassini sheds light on the tiny moons that orbit within Saturn's vast ring system.
Hayabusa 2 Finds Asteroid Ryugu Is Dark & Dry
Hayabusa 2’s asteroid Ryugu has some unexpected characteristics. In particular, its dry surface could spell trouble for current theories about how Earth obtained its water.
Bumpy Road Ahead For NASA’s Osiris-REX
Asteroid Bennu is turning out to be a hazardous place for the NASA spacecraft to sample: It has uneven, rugged terrain and occasionally even hurls rocks into space.
New Results Probe the Origin of "Ultima Thule"
As observations trickle in from NASA's New Horizons spacecraft, mission scientists have new insights on how their two-lobed target formed in the Kuiper Belt.
‘Oumuamua "Sped Up" in the Inner Solar System. This Might Be Why.
Astronomers think a jet-powered rocking motion could solve the puzzle.
Pluto and Charon Are Missing Small Craters
Scientists studying New Horizons images of craters on Pluto and its moon Charon have found that the Kuiper Belt must contain fewer small objects than expected — which suggests the outer solar system hasn’t changed much since its earliest days.
Hayabusa 2 Touches Down, Collects Asteroid Sample
The Japanese spacecraft Hayabusa 2 has touched down on Ryugu, the asteroid it's been orbiting since last summer, and collected a sample from its surface.
Meet Hippocamp, Neptune's Smallest Moon
Although first recorded by Hubble in 2004, subsequent imagery shows that this tiny, innermost moon of Neptune likely had had a violent history.
New Astro Camera Spots Thousands of Celestial Flare-ups
A vision from 70 years ago, the Zwicky Transient Facility has produced a wave of discoveries — but it’s only a hint of what’s to come.
Hubble Sets Its Sights on the Ice Giants
New Hubble Space Telescope images reveal an expanded polar cap on Uranus and another mysterious dark vortex on Neptune.
Comet Iwamoto Ascends and Brightens
Comet Iwamoto is visible as a binocular target from a dark sky. Follow it this week as it passes from Virgo into Leo.
Curiosity Rover Exposes Mountain’s Origin
Scientists have used an innovative measure of Mars's gravity to reveal the origin of the mountain the rover is exploring.
Did a Mars-size Body Bring Life-essential Elements to Earth?
Collision with a Mars-size body — the same body thought to have formed the Moon — might also have brought life-supporting volatile elements to Earth.
Amateur Scopes Help Find Planet Formation’s Missing Link
A surprisingly inexpensive setup of amateur equipment is helping astronomers on their quest to find Kuiper Belt objects of every size to better understand how planets formed in our solar system.
Astronomers Identify Weather Cycle on Jupiter
Astronomers have identified a periodic clearing at the gas giant's equator; amateurs may have spotted the change at the end of 2018.
Asteroid Impacts Increased 290 Million Years Ago, Lunar Craters Reveal
Researchers have estimated the ages of craters on the lunar surface, finding that the rate of large impacts nearly tripled 290 million years ago — an increase that might be ongoing.
Initial Results from the Ultima Thule Flyby
NASA's New Horizons made history when it flew by "Ultima Thule" on New Year's Day, but the science return is only beginning. Here's the latest from mission principal investigator Alan Stern.
