Saturn's giant moon Titan may not have a vast underground ocean after all.

Titan instead may hold deep layers of ice and slush more akin to Earth's polar seas, with pockets of melted water where life could possibly survive and even thrive, scientists reported Wednesday.

A stray comet from another star swings past Earth this week in one last hurrah before racing back toward interstellar space.

Discovered over the summer, the comet known as 3I/Atlas will pass within 167 million miles (269 million kilometers) of our planet on Friday, the closest it gets on its grand tour of the solar system.

Legend once had it that the huge, three-toed footprints scattered across the central highlands of Bolivia came from supernaturally strong monsters — capable of sinking their claws even into solid stone.

Then scientists came here in the 1960s and dispelled children's fears, determining that the strange footprints in fact belonged to gigantic, two-legged dinosaurs that stomped and splashed over 60 million years ago, in the ancient waterways of what is now Toro Toro, a village and popular national park in the Bolivian Andes.

Scientists have detected what they believe to be lightning on Mars by eavesdropping on the whirling wind recorded by NASA's Perseverance rover.

A telescope in Chile has captured a stunning new picture of a grand and graceful cosmic butterfly.

The National Science Foundation's NoirLab released the picture Wednesday.

NASA unveiled close-up pictures on Wednesday of the interstellar comet that's making a quick one-and-done tour of the solar system.

Discovered over the summer, the comet known as 3I/Atlas is only the third confirmed object to visit our corner of the cosmos from another star. It zipped harmlessly past Mars last month.

Three Chinese astronauts stranded at their nation's space station after their spacecraft was apparently hit by space debris departed for home Friday using the craft that had brought a replacement crew, China's space agency said.

Their capsule was expected to land in a remote part of northwest China's Inner Mongolia region later the same day.

Space weather forecasters issued an alert on Tuesday for incoming severe solar storms that could produce colorful northern lights and temporarily disrupt communications.

In the past few days, the sun has burped out several bursts of energy called coronal mass ejections that could reach Earth Tuesday night and early Wednesday. The potential severe geomagnetic storms could disrupt radio and GPS communications, according to forecasters with the National Oceanic and Atmospheric Administration.

Scientists have long debated whether dinosaurs were in decline before an asteroid smacked the Earth 66 million years ago, causing mass extinction.

Three scientists won the Nobel Prize in medicine Monday for discoveries about how the immune system knows to attack germs and not our own bodies.