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1. Astronomy makes use of lots of very large and very small
numbers. For instance, the mass of the Sun is
2,000,000,000,000,000,000,000,000,000,000 kg while the mass of an
electron is only 0.000000000000000000000000000000911 kg. These numbers
are hard to work with and even harder to key into a calculator - we
need a better way of representing the very large and the very
small. The answer is scientific notation which makes use of powers of
ten. So the masses of the Sun and the electron are usually written
2*1030 kg and 9.11*10-31 kg, respectively.
a) Go to the scientific notation tool at http://janus.astro.umd.edu/astro/scinote/
and practice converting between normal numbers and scientific notation
until you can do this type of problem in your sleep! Click the "help
me" button if you have any trouble. Then take the quiz; print out a
copy of your corrected quiz to hand in.
b) Now practice
multiplying and dividing scientific notation numbers. See the help
file for some examples. When you are comfortable, take the
multiply/divide quiz until you get them all right. Hand in a corrected
copy of your quiz.
2. The Universe is a big place! To get a sense of just how large it is, go
to the Astronomical Distances program at http://janus.astro.umd.edu/astro/distance/.
a) How fast can you make the spaceship travel?
b) At maximum speed, how quickly can you get to the Moon? To Pluto?
c) When we look at a galaxy in the Coma cluster, how long ago did the light that we see leave that galaxy?
d) If you could drive to the Moon and Pluto, how long would each journey take?
3. The Universe is also a very old place. How old? 13.7 billion
years! To get a sense of this immense amount of time, go to the Universe Timeline webtool at
http://janus.astro.umd.edu/astro/times.html and
compress the history of the Universe into one year.
a) On what dates
do the Sun, Earth, and Moon form?
b) When does life and
complex multicellular life arise?
c) How long did the dinosaurs last?
d) How much time does the
entire history of the human race occupy?
4. Finally, go to the class webpage at http://www.astro.umd.edu/~hamilton/ASTR109
and click on the image at the top. The nine planets are displayed with
their correct relative sizes and in order of their distance from the
Sun.
a) Name the planets in this order.
b) What are the
first four planets primarily made of (choose from rock, ice, gas)? How about the
next four?
c) What is Pluto made of? You may have heard that
astronomers have been arguing about whether Pluto is a planet - why do
you think that this is an issue?
Think about these questions and explore the ASTR109 website further on your own!