July 25-31, 2013, Current Events Lesson Plan
Current Event:
A new image of Comet ISON taken by the Hubble Space Telescope is giving the public a tantalizing preview of what the deep-space traveler may look like when it makes its maiden voyage around the sun in late November. Some astronomers think the comet could outshine the full moon, rivaling the display put on by the Great Comet of 1860. That comet could be seen during daylight hours without a telescope. However, other researchers caution that the comet could fizzle. So-called sungrazing comets like ISON often break up or boil away during their perilously close passage by the sun. The comet also might not make it through the Asteroid Belt. Russian astronomers discovered Comet ISON in September 2012. The comet is named for the International Scientific Optical Network, a group of observatories in 10 countries. At this point, the nucleus of the comet is less than 3 miles (5 kilometers) in diameter, though its dusty head is much larger–about 3,100 miles (5,000 kilometers) across. Its tail is an amazing 186,400 miles (300,000 kilometers) long, thanks to the prodigious amount of carbon dioxide escaping from the comet each day.
Objective:
A comet is a bright heavenly body with a star-like center and often with a cloudy tail of light. A comet’s nucleus (center) is a ball of ice and rocky dust particles. As a comet nears the inner solar system, heat from the sun vaporizes some of the ice on the surface of the nucleus. The comet spews gas and dust particles into space. This gas and dust forms the comet’s coma. Radiation from the sun pushes dust particles away from the coma. These particles form a tail called the dust tail. Because comet tails are pushed by solar radiation and the solar wind, they always point away from the sun. Most of the comets that can be seen from Earth travel around the sun in long, oval orbits. We can see comets because the gas and dust in their comas and tails reflect sunlight. Also, the gases release energy absorbed from the sun, causing them to glow. The best-known comet is Halley’s Comet, which appears in the sky about every 76 years. The Behind the Headlines news stories and related World Book articles explore comets and other astronomical topics.
Words to know:
- Astronomy
- Comet
- Edmond Halley
- Halley’s Comet
- Hubble Space Telescope
- National Aeronautics and Space Administration (NASA)
- Oort cloud
- Solar system
- Space exploration (Probes to comets)
- Spitzer Space Telescope
- Telescope
Discussion Topics:
1. In Chicago, there is a joke about Halley’s Comet coming twice (1910 and 1986) since the last time the Cubs won the World Series (1908). Ask your students to name historical events that have happened since the last time Halley’s Comet appeared in 1986. (Students might say the Soviet Union collapse [1991], Oklahoma City bombing [1995], September 11 terrorist attacks [2001], Iraq War [2003-2011], Indian Ocean earthquake and tsunami [2004], Hurricane Katrina [2005], Japan earthquake and tsunami [2011].) Ask your students what they think is the most important event since 1986.
2. Ask your students to debate, “Astronomy is the most interesting school subject.”
3. Ask your students to use the World Book’s Timelines feature to create a timeline of famous comets. (Students may wish to use the Famous comets table in World Book’s Comet article for help. Students can either make a timeline of the comets’ first sightings or they can use the Period of orbit column to make a timeline of comet sightings.)