April 2-8, 2015, Current Events Lesson Plan
Current Event: How to Become a Star
Recently, a team of astronomers discovered a protostar that, in a relatively short period of time, underwent a significant change in how energy flows from its core. A star develops from a giant cloud of gas and dust. The cloud begins to collapse inward, becoming smaller, and the collapsing material becomes warmer, and its pressure increases. Eventually the collapse slows to a gradual contraction. The inner parts of the clump form a protostar, a ball-shaped object that is no longer a cloud but is not yet a star. Surrounding the protostar is an irregular sphere of gas and dust that had been the outer parts of the cloud. In 1996, astronomers first examined a massive protostar about 4,200 light-years from our solar system. Back then it was releasing shockwaves in a spherical formation from its center. Astronomers could detect these shockwaves because they excited particles in the protostar’s surrounding cloud of gas, causing them to glow. When the team looked at the star in 2014, they noticed that the shockwave-containing region had changed from a sphere to an elongated oval. Such a quick change is rarely detected when studying the stars.
Objective:
Stars are huge, shining balls in space that produce a tremendous amount of light and other forms of energy. The sun and most other stars are made of gas and a hot, gaslike substance known as plasma. Stars come in many sizes. The sun’s radius (distance from its center to its surface) is about 432,000 miles (695,500 kilometers). But astronomers classify the sun as a dwarf because other kinds of stars are much bigger. Some of the stars known as supergiants have a radius about 1,000 times that of the sun. The smallest stars have a radius of only about 6 miles (10 kilometers). Stars are grouped in huge structures called galaxies. The sun is in a galaxy called the Milky Way that contains hundreds of billions of stars. There are billions, possibly even trillions, of galaxies in the universe. Each galaxy consists of from hundreds of thousands to trillions of stars. Thus, billions of trillions of stars may exist. But if you look at the night sky far from city lights, you can see only about 3,000 of them without using binoculars or a telescope. The Behind the Headlines news story and related World Book articles explore stars and other astronomical topics.
Words to know:
Discussion Topics:
1. Constellations are groups of stars visible within a particular region of the night sky. Ask your students to name some constellations. (Students might say Andromeda, Aries, Cancer, Canis Major, Canis Minor, Gemini, Leo, Orion, Pisces, Sagittarius, Southern Cross, Ursa Major, and Ursa Minor.) Note: the Big and Little Dippers are not constellations, but form part of Ursa Major (Big Dipper) and Ursa Minor (Little Dipper).
2. Have your students debate the topic, “It is important to study stars and other parts of the universe.”
3. Ask your students to use World Book’s Timelines feature to view or add to the Milestones of Star Study timeline. (Students may wish to use World Book’s “Star” article for help.)