How big is our galaxy?
The Milky Way’s disk spans at least 100,000 light-years and probably contains several hundred billion stars, which makes our home […]
How many galaxies are there in the universe?
Quite a few. Most estimates place the number of galaxies at around 100 billion. Most of those galaxies are little
What is the largest telescope?
The largest visible-light telescope currently in operation is at Gran Canarias Observatory, and features a 10.4-meter (34-foot) primary mirror. The
Who invented the telescope?
The true inventor of the first telescope is somewhat difficult to nail down. However, the first person to apply for
What causes tides?
For the most part, the rise and fall of the tides is caused by the gravitational influence of the Moon.
How big is the solar system?
The farthest known object orbiting our Sun is a ball of ice and rock unofficially called FarFarOut, which lies about
Is there a tenth planet in our solar system?
No. On August 23, 2006, the International Astronomical Union decided that the solar system contains only eight planets. Pluto, which
How often do all the planets line up?
Alignments of the fast-moving inner planets can occur as regularly as every few months or so, while groupings of the
How was the size of Earth first measured?
Earth’s circumference was first accurately measured more than 2,000 years ago by the Greek astronomer Eratosthenes, who at the time
What causes the Northern and Southern Lights?
The famous Northern and Southern Lights — Aurora Borealis and Aurora Australis for those Latin lovers among us — are