Reference Astronomical twilight is the darkest phase of twilight that a viewer sees before the last refracted sunlight leaves the horizon. It usually occurs twice a day.
Reference The constellations of the western zodiac are now used to orient skywatchers, navigate without technology and inspire interest in the night sky.
Reference Explore our 25 weird solar system facts and see how our neighborhood is stranger than we could ever imagine.
Reference Mars missions have been launching for over 50 years. Humanity has sent orbiters, probes and landers to Mars but not every mission has been successful.
Reference The global average surface temperature lies somewhere around 57 degrees Fahrenheit (13.9 degrees Celsius).
The speed of light puts a speed limit on matter, lets us peer back into the history of our universe, and has deep implications for physics and space travel.
REFERENCE Inspiration4 was the world's first orbital spaceflight unsupervised by professional astronauts, using commercial equipment to launch civilian space enthusiasts into orbit.
Reference There are a few good theories for a multiverse — an infinite number of parallel universes besides our own.
Einstein's paper on special relativity revolutionized light, light speed, matter and energy with a deceptively simple equation.
A biography of Soichi Noguchi, JAXA astronaut and only non-American so far to fly in the space shuttle, the Soyuz and SpaceX Crew Dragon.
Tianwen-1 is the ambitious first independent interplanetary mission from China, now in orbit around Mars.