Peak viewing for use will be Friday night December 13 into the pre-dawn hours on Saturday the 14th with a decent number of meteors likely still visible the evening of December 14th as well. And unlike other meteor showers, which are typically best viewed during the couple of hours prior to sunrise, with the Geminids, under clear skies you often can spot some bright streaks flying by early in the evening with the show only ramping up through the night.
The cold dry air of December, being free from haze, which often obscures meteors during the warmer months, is one of the reasons, along with the typically high shooting star rates, that makes this a great meteor shower to check out. All you need to do is look up. It doesn’t matter which direction you look, as long as you’re looking up. And, for the best potential of seeing as many shooting stars as possible, try to find a place with as wide a view of the sky and as far from light pollution as possible. And although the meteor rates will be much lower, the Geminids will remain active through the 17th.
WHY THE SHOW
The Geminid meteor shower occurs as the Earth passes through the dust cloud left behind every time the 3.6 mile wide asteroid, known as 3200 Phaethon, circles the sun on a period of every 1.4 years. Each time 3200 Phaethon makes its closest approach to the sun on its journey through the solar system, its surface heats up to a temperature of approximately 700 degrees C causing it to shed particles creating the dust cloud.
Fun fact, most meteor showers are caused by particles shed by comets, this meteor shower and the Quadrantids in January, however, are the only two major meteor showers that result from something other than a comet.
The particles that make up the dust cloud are tiny, generally the size of grain of sand or piece of granola and hit the top of the atmosphere, 50-75 miles up, at speeds of about 18-22 miles per second or around 78,000 miles per hour (which is actually considered slow.) The relatively slow speed of the particles make the Geminid’s light streak easy to spot. That light streak is caused by the huge amount of friction that occurs between the meteor and the upper atmosphere which flash heats the air molecules along the path to thousands of degrees F creating a cushion of super heated air that runs in advance of the particle. When those super heated molecules cool, which happens almost instantaneously, they release light which creates the streak that we see. The faster the particle is moving, the more friction and thus the hotter the air, and subsequently the brighter the meteor streak.
According to Sky & Telescope, the reason this and other meteor shows are better in the hours just before sunrise versus early in the evening is due to the fact that the Earth’s orbital velocity combines with the velocity of the shooting stars in the hours prior to sunrise which increase the arrival speeds that then goes on to creates brighter streaks. During the evening, however, the relative particle impact speed is lower so the meteor streaks are more faint making less of the visible in most cases.