Why do stars twinkle?
Because stars are so incredibly distant, to our eyes they appear strictly as points in the night sky. Irregularities in […]
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
How fast is Earth moving through space?
To begin with, Earth is rotating on its axis at the familiar rate of one revolution per day. For those
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
Why does the Moon look bigger at the horizon?
The “Moon illusion,” in which the Moon appears larger than normal when close to the horizon, is not the result
Can solar flares and sunspots affect Earth?
While no direct link between sunspots and Earthly events, such as volatile stock markets, has ever been found, extremes in
What is the nearest star?
Of course, the nearest star to Earth is the one we see every day — our dear old Sun. At
How many stars are in the Milky Way?
Most estimates place the number of stars in our galaxy at between 100 billion and 500 billion.
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