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 […]
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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
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Who invented the telescope?
The true inventor of the first telescope is somewhat difficult to nail down. However, the first person to apply for
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What causes tides?
For the most part, the rise and fall of the tides is caused by the gravitational influence of the Moon.
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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
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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
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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
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Why do stars twinkle?
Because stars are so incredibly distant, to our eyes they appear strictly as points in the night sky. Irregularities in
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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
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