Our Star, the Sun
The Sun was born about 4.6 billion years ago from the gravitational collapse of a vast cloud of gas and […]
Our Star, the Sun Read More »
The Sun was born about 4.6 billion years ago from the gravitational collapse of a vast cloud of gas and […]
Our Star, the Sun Read More »
Mercury's surface closely resembles the Moon's. It is covered by impact craters, ancient lava flows, and quake fault lines. Mile-high
This bright ring of light is quite common. It’s related to the same process that creates rainbows: refraction. In this
What causes the bright halo that sometimes surrounds the Moon? Read More »
Observatories, like so much of astronomy, are truly ancient features of human culture; retracing the steps of the first person
Who built the first observatory? Read More »
Maps of the stars are nearly as ancient as human culture itself; inscriptions describing the positions of stars and constellations
Who made the first map of the universe? Read More »
Earth’s circumference was first accurately measured more than 2,000 years ago by the Greek astronomer Eratosthenes, who at the time
How was the size of Earth first measured? Read More »
Of course, the nearest star to Earth is the one we see every day — our dear old Sun. At
What is the nearest star? Read More »
The farthest known object orbiting our Sun is a ball of ice and rock unofficially called FarFarOut, which lies about
How big is the solar system? Read More »
No. On August 23, 2006, the International Astronomical Union decided that the solar system contains only eight planets. Pluto, which
Is there a tenth planet in our solar system? Read More »