Exploration of the Universe

1. Exploration of the Universe For thousands of years humans have looked up at the sky in wonder.As they observed they learned the sky was constant and predictable.They learned to tell the time of day, the date, the weather, their position and the occurrence of tides and eclipses.Many other events were thought to depend on the skies and astrologers were often employed to read the sky.This type of prediction has nothing to do with science however. In this same vein many different cultures have myths that are associated with asterisms (distinctive star patterns such as the Big Dipper) or constellations (an officially registered grouping of stars such as Leo). Today the sky is divided up into 88 regions, each associated with a constellation (see constellation map) recognized by the International Astronomical Union. Hand out star map

2. Movement of Celestial Bodies The Sun moves from east to west across the sky. The Sun moves through the Zodiac constellations once per year.The Moon moves from east to west across the sky but the moon rises a bit earlier each day.The stars all revolve around Polaris (the North Star), one complete revolution every 24 hours although each star rises four minutes earlier each night.Planets seem to move with the stars but after simple observations it can be seen that planets wander through the sky.More careful observations show that planets move eastward through the sky although about once per year they experience retrograde motion where the planet moves westward (backward) for a week or so. Bring in telescope and observe sunspots Set up astronomy nights.

3. Stargazing Activity • Observe the setting sun (or rising sun) from the same position and record the time and location of the sunset. • Observe the moon from the same position at the same time and record its location. Draw the shape of the moon. • Observe Jupiter from the same position at the same time and record its location. • Observe Venus (in the morning!!) from the same position at the same time and record its location. • Each set of observations (hopefully 10 at least) should be on its own sheet of paper. Draw the landscape in front of you as well.

4. Moon Nov. 17 8:28 pm Nov. 14 8:15 pm Nov. 12 8:23 pm

5. Retrograde Motion The word planets comes from the Greek word for wanderer. Stars move very slowly in the sky relative to other stars but Planets change their position quite quickly relative to stars.Outer planets (Mars, Jupiter, Saturn, Uranus, Neptune) also display retrograde motion. Planets move eastward in the night sky but once a year for a month or two they move westward.This “reversal” is called retrograde motion. Try the Retrograde Motion Activity. Celestial Motion The Greek philosopher Aristotle (500 BC) thought that all of the planets and the Sun orbited Earth (geocentric model).All of these objects were thought be contained in a sphere called the firmament of fixed stars or celestial sphere. These ideas dominated until the 1500’s but the retrograde motion could never be explained adequately by geocentric model.Ptolemy (100 AD) added epicycles (circles on circles) but still the geocentric model didn’t fit the night sky observations.

6. Copernicus in the 1500’s proposed a heliocentric model which had the planets, including Earth, orbiting the Sun. This allowed the motion of all planets to fit the night sky observations almost perfectly. Many people were against this model but slowly this model was accepted.One piece of evidence which supported this model was that Galileo found 4 moons orbiting Jupiter (with the better telescopes he designed).He also found that Venus displayed phases (just like the Moon). Copernicus’s model was excellent but not perfect. The wonderful observations of Brahe (late 1500’s) and the calculations of Kepler showed that the planets actually move in ellipses around the Sun.Finally Newton’s discovery of a theory of gravity explained why the planets orbit the Sun and moons orbit planets. Kelvin Scale for Temperature 1 degree change on the Kelvin Scale is equal to 1 degree change on the Celsius Scale. 273 K is equal in temperature to 0 o C.

7. Consulting the Planetary Expert: You Fill out the table on p. 446 (in your notebook) by consulting the planetary data cards on p. 448 – 452. Saturn temp is -180 not -18 Make a list for each characteristic arranging them in order from least to greatest. Use the Kelvin scale for temperature. Write down the value of the characteristic as well. State in months the orbital period of Mercury and Jupiter. State in hours the rotation period of Saturn and Venus. What is the diameter of Jupiter and Venus in km? In km how far away from the Sun are Mars and Neptune? Answer questions 1-7 p. 447 Some answers may need information from p. 443 – 445 while other answers need information from the planetary data cards.

8. On a legal sheet of paper show the relative distances from the Sun of all of the planets (Pluto optional). On a legal sheet of paper show the relative diameters of all the planets, in no particular arrangement, by drawing circles of the proper relative size. Colour the planets. Modeling the Solar System p. 453 Outdoor Activity Moon Phases Draw one diagram of the Sun, Earth and the Moon showing how a full Moon, half Moon, crescent Moon, gibbous Moon and new Moon are produced. (Bonus, show a diagram of the Sun, Earth and a half Venus. Read p. 454 and make brief notes on Asteroids, Comets, Meteors and Meteorites. Chapter 13 Review p. 458-459 Questions 1-8