00:00 When a comet soars across the sky, twin trails of gas and dust streak behind it.
00:05 Now a new study suggests that the moon may have a similar tail, but it's only visible
00:09 once a month when Earth passes directly through it.
00:13 In the 1990s, astronomers noticed that the moon has a tail.
00:21 It isn't visible to the naked eye, but using a special telescope, they were able to see
00:25 the faint orange glow of sodium streaking off of the moon.
00:28 This sodium tail comes from lunar soil that gets blasted into space when asteroids hit
00:32 the moon, and it's only visible from Earth once a month during a new moon when the moon
00:37 sits between Earth and the sun.
00:40 When these three bodies are aligned, photons from the sun push that airborne sodium hundreds
00:44 of thousands of miles away from the moon.
00:46 Earth's gravity then pinches that sodium tail into a long beam that wraps around our planet
00:51 and shoots out the other side.
00:53 That beam is about 50 times too dim for humans to see with the naked eye, but when astronomers
00:58 look at it with the right telescopes, they see a fuzzy orange spot about five times wider
01:03 than the full moon.
01:05 After a few days, it vanishes.
01:07 That fuzzy sodium spot always appears at the same time each month, but strangely, its brightness
01:12 is constantly changing.
01:13 In a new study published this month in the journal JGR Planets, astronomers tried to
01:19 figure out why.
01:20 After looking at 14 years worth of lunar photos, they figured out that the spot tends to appear
01:24 brighter when more random meteors are sighted over Earth.
01:28 What's the connection?
01:30 More meteors over Earth means more asteroids slamming into the surface of the moon, which
01:34 doesn't have an atmosphere to protect it like our planet does.
01:38 According to the researchers, these random meteors tend to be larger, faster, and more
01:42 powerful than the broken up rocks that are parts of the annual meteor showers that we
01:47 see like the Leonods in November.
01:50 Larger meteors mean bigger impacts on the moon, which means a bigger cloud of sodium
01:54 flying into space and eventually passing over Earth.
01:57 And so, scientists on Earth see a brighter spot when our planet focuses that cloud into
02:03 a beam that passes around our planet.
02:06 The moon's tail and the beam it creates are both harmless to our planet, which has a strong
02:10 atmosphere to protect it from those pesky particles.
02:13 So the next time a new moon rises, take a minute to thank our friend in the sky for
02:17 sprinkling us with a little cosmic pixie dust.
02:20 (Music)
Comments