Gravity

Over the course of the Apollo moon missions in the 1960s and 1970s, several NASA astronauts walked on the lunar surface.

Einstein's general theory of relativity beautifully describes the nature of gravity and its effect on large objects in the universe. However, there are alternative explanations.

This new model does not require any negative mass exotic material and offers a very simple design.

Astronauts were allowed to hit under and over the net and decided that the primary goal was in continuing to get the ball past the net in conditions that lack a gravitational constant.

Any potential end is still 30 to 40 billions of years away, researchers said, but there's hope the universe could expand infinitely.

Low gravity, surprising surfaces and chunky suits make a recipe for tumbling.

Astronauts on the International Space Station do not even have sinks because of the way water behaves in microgravity.

Stronger gravity requires stronger—and pricier—rockets to overcome.

Millions have had their cosmic horizons widened by his best-selling books; and even more, around the world, have been inspired by a unique example of achievement against all the odds.

Scientists hit the road with a high-precision clock hooked up to a trailer.

Weak nuclear force is stronger than gravity, but weaker than, you know, strong nuclear force.

Thank Newton for our understanding of rainbows and the motion of soccer balls.

The recently patented technology could one day save an astronaut from becoming lost in space.

Because the change travels at the speed of light, it could tell scientists the real size of an earthquake in just three minutes.

The astrophysicist most recently chimed in about "Titanic." Is he veering away from his strictly science-based reviews?

The galaxy in question appears as it was 11 billion years ago, just 2.7 billion years after the Big Bang.

Einstein predicted that gravity and light could be used to calculate the mass of a star. But he never thought scientists could actually do it.

The theory breaks with the popular idea that expansion is caused by dark energy and suggests energy for expansion would never run out.

Panels at the philosophy and music festival feature discussions of topics as varied as sexuality, feminism, gravity and democracy.

An American flight engineer who landed back on Earth in Kazakhstan Monday documented his months-long journey on social media.