Earth, Comet To Meet

By Dave Cuomo, Willard Smith Planetarium Supervisor


On the morning of November 17, Earth will collide with a comet.

Well not exactly a comet but the debris left behind from a comet, in this case 55P/TEMPEL-TUTTLE. As Earth passes through this debris field the small objects will burn up in Earth’s atmosphere and we will see them as the Leonids Meteor shower.

Comets are chunks of ices mixed with minerals that are in highly elliptical orbits around the Sun. While the ice is mostly water, ice comets also contain other ices such as Carbon Monoxide, Carbon Dioxide, Methane and Nitrogen. As a comet gets closer to the Sun the heat starts to melt the ices and the solar wind blows the dust and gas away from the sun forming the well-known tail. Comets actually have two tails: the Ion, or Gas Tail directly pointing away from the Sun, contains the volatilized gas molecules blown away by the Sun’s heat and Solar Wind. The second tail is the dust tail and contains larger bits of dust and ice. These bits are the size of smoke particles and are also blown away by the solar wind. Larger particles about the size of sand grains or peas trail behind the comet. This trail of debris stays in orbit around the Sun. Once a year, as the Earth passes through the debris field, the tiny particles of dust hit the Earth’s atmosphere at upwards of 50,000 mph. These particles are no larger than a pea, but due to the great speeds involved, the heat generated causes them to burn up as bright streaks across the sky and are seen asmeteors.

To see the Leonid Meteor shower, go to a dark sky location looking towards the East. Best viewing will be on the mornings of November 17 & 18 between 1:00 a.m. and 2:00 a.m.  As you look to the East, you will see a bright Jupiter just rising and above that you will see the stars of the constellation Leo. The meteors will radiate out from the area of the lion’s neck and head. This gives the meteor shower it’s name.

Meteoroid: A small piece of rock or metal traveling in space.

Meteor: When a meteoroid hits the Earth’s atmosphere it changes into a meteor. It burns up due to friction with the atmosphere and can be seen as a bright light streaking across the sky.

Meteorite: Sometimes a large enough object will survive entry and land on Earth. This is a Meteor. Meteors will often have a chared exterior called the fusion crust. Metallic meteorites can appear visibly melted. Correctly identifying a meteor can be tricky and even experts can be confused.