There are 161 active volcanoes in the United States, more than 1/3 of which have been classified as posing a high threat to nearby communities. A new law aims to improve volcano monitoring.

Liftoff is targeted at 11:30 p.m. EDT, with a 4-hour launch window. SpaceX is calling the launch its most difficult ever, because the rocket must release 24 satellites into 3 different orbits.

The Mars Helicopter will launch with Mars 2020. It'll be the first vehicle in history to attempt to establish the viability of heavier-than-air vehicular flight on another planet. Plus ... space engineers celebrate with a selfie after attaching the Mars 2020 rover's remote sensing mast.

The American Astronomical Society - chief organization for US astronomers - said it is in conversations with SpaceX about the impending launch of 12,000 Starlink satellites. The astronomers worry the satellites will interfere with their work of understanding the universe.

Nearly 100 countries have already signed up to organize national campaigns, to provide the public with an opportunity to vote. The deadline is July 30 to express interest in organizing a national campaign. The IAU will announce results in December.

Check out this optical illusion and find out what it says about your brain.

A new study suggests a series of supernovae - peaking 2.6 million years ago - might have triggered earthly events that promoted proto-humans’ upright walking.

Will Elon Musk's plan to launch 12,000 Starlink satellites - aimed at bringing internet access to the world - interfere with astronomy? Astronomer Guy Ottewell ponders this question.

A hundred years ago today, Einstein’s theory of gravity was first put to the test when Arthur Eddington observed light “bending” around the sun during a solar eclipse. A century later, scientists are still searching for the limits of the theory.

Watch 2 Russian cosmonauts perform a spacewalk outside the International Space Station (ISS) on Wednesday, May 29.