We on Earth get to take in the wonder of a meteor shower typically when our planet passes through the trail of a comet. The bits of rock and debris burn up when they hit Earth’s dense atmosphere, and streak across the sky.
The Geminid meteor shower is nearly 200 years old, according to known records — the first recorded observation was in 1833 from a riverboat on the Mississippi River — and is still going strong. In fact, it’s growing stronger. That’s because Jupiter’s gravity has tugged the stream of particles from the shower’s source, the asteroid 3200 Phaethon, closer to Earth over the centuries.
Named after Gemini
The Geminid meteor shower can be seen every year between December 4 and December 16, with its peak activity being around December 13-14. The shower owes its name to the constellation Gemini because the meteors seem to emerge from this constellation in the sky.
The tiny bits of rock and debris that produce the Geminids are believed to originate from a small, 3-mile-wide asteroid named 3200 Phaethon, which was not discovered until 1983 (while the annual Geminid shower has been recognized since 1862). Every 1.4 years, Phaethon’s orbit takes it closer to the Sun than any other known asteroid, heating its surface to roughly 1,300 °F (700°C).
This extreme heating is believed to cause Phaethon to crack and shed debris, which then sparsely spreads out all along the asteroid’s orbital path, much like a flowing river of pebbles. Though Phaethon’s orbit around the Sun takes 1.4 years, Earth passes through Phaethon’s river of debris every December, which ultimately produces the beautiful Geminid shower we have grown to know and love.
When to see them
The meteors tend to peak about 2 a.m. your local time wherever you’re observing from, but can be seen as early as 9-10 p.m.
The Geminids, as their name implies, appear to emanate from the bright constellation Gemini (the twins). To find Gemini in the Northern Hemisphere, look in the southwestern sky for the constellation Orion, which is easy to spot by the three stars in the hunter’s “belt.” Then look just up and to the left of Orion to see Gemini, high in the southwestern sky. In the Southern Hemisphere, Gemini appears to the lower right of Orion and both will hang in the northwestern sky.