Astronomy Fun Fact #55

One of the most accurate ways to measure time comes from space!

There's a type of star called a pulsar that rotates at such a predictable rate that we can use them to keep track of time. In fact, pulsars are so accurate the the European Space Agency actually used them to calibrate atomic clocks, which lag behind by about 1 second every 10 million years or so, depending on what kind of atom is used.