space

Some scientists say the comet last visited the Earth around 50,000 years ago.

Marking the latest step in the commercialization of space, the SpaceX mission has launched four civilians, including a billionaire CEO, a physician assistant and a geoscientist.

The two countries' space agencies say the proposal, which sets no time frame, could include an orbiting station, a base on the surface, or both.

The astronauts will spend around eight days in orbit in what would be a new step for joint private-public space missions.

On Monday evening, Jupiter and Saturn appeared closer to each other in the sky than they have for hundreds of years in what has become known as the Great Conjunction.

At least, that's how it will look to someone craning their head aloft. On the winter solstice, the pair of gas giants will appear closer to each other in the night sky than they have in centuries.