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MHR • Unit 4 Space Exploration
The average temperature of the universe is about –270°C, or 3° above absolute zero. This higher- than-expected temperature is thought to be the result of heat left over from the original formation of the universe. This is sometimes referred to as “fossil glow.” Find out more about this topic. Start your search at www.bcscience9.ca.
In 2001, NASA sent another spacecraft out to gather more information about cosmic background radiation. This one is called the Wilkinson Microwave Anistropy Probe (WMAP), and it is able to make more precise measurements than have ever been made before. The microwave radiation data collected by the probe has been mapped, as shown in Figure 10.8. Blue shows the slightly denser regions of the early universe. These, many scientists believe, are the areas where galaxies formed as a result of gravity. Red shows the less dense regions that became emptier and emptier as the universe expanded. These WMAP results have confirmed the data gathered by the COBE satellite, giving scientists greater understanding about the universe’s early moments.
10-1B
TheUniverseinaSpoonfulofSand
In 1999, measurements taken by the Hubble Space Telescope led astronomers to speculate there were 125 billion galaxies in the universe. A German supercomputer has run simulations that suggest the number could even be as high as 500 billion galaxies. The numbers used to measure quantities in space are enormous. In this activity, you will compare the number of grains of sand in a given volume with the estimated number of galaxies in the universe.
Materials
• 100 mL sand
• one 0.5 mL measuring spoon • paper
• 1 cm3 box
What to Do
2. Add up your two counts. Compare your total with the totals counted by your classmates. Note the range in totals for the same quantity of sand.
3. Count the number of spoonfuls it takes to fill the 1 cm3 box. Estimate the number of grains in that 1 cm3 container.
What Did You Find Out?
1. Estimate how many grains of sand would be found in: (a) 1m3
(b) abathtub (c) 1km3
2. Determine the estimated volume required to hold 500 billion sand grains.
3. Why would it be incorrect to estimate the size of the universe based on the volume of 500 billion galaxies?
4. Why might the estimate of 500 billion galaxies be proven wrong?
1.
Working with a partner, place 0.5 mL of sand on a piece of paper and divide it in half into two samples. While you count the sand grains in one sample, your partner will count the grains in the other.
The WMAP microwave radiation map
of the universe
Find Out ACTIVITY
Figure 10.8