Ch. 1 HW

How is an astronomical unit (AU) defined? Give an example of a situation in which this unit of measure would be convenient to use.

The average distance between Earth and the Sun; used to measure distances across the solar system. 1 AU = 1.496 x 10^8 km = 92.96 million miles Avg distance between Sun & Jupiter is 5.2 AU

What are the advantages of using powers-of-ten notation?

All the cumbersome zeros that accompany a large number are consolidated into one term consisting of 10 followed by an exponent, which is written as a superscript. The exponent also tells you how many tens must be multiplied together to give the desired number, which is why the exponent is also called the power of ten. A negative exponent tells you to divide by the appropriate number of tens. Because it bypasses all the awkward zeros, powers-of-ten notation is ideal for describing the size of objects as small as atoms or as big as galaxies.

How are scientific theories tested?

An important part of a scientific theory is its ability to make predictions that can be tested by other scientists. If the predictions are verified by observation that lends support to the theory and suggests that it might be correct. If the predictions are not verified, the theory needs to be modified or completely replaced.

What is the difference between a hypothesis and a theory?

Hypothesis= a collection of ideas that seems to explain what is observed Theory= a body of related hypotheses can be pieced together into a self-consistent description of nature

What is the advantage to the astronomer of using the light year as a unit of distance?

Light year= distance that light travels in one year This is a useful concept because the speed of light in empty space always has the same value, 3.00 x 10^5 km/s or 1.86 x 10^5 mi/s. Physicists often measure interstellar distances in light-years because the speed of light is one of nature's most important numbers.

Describe the role that skepticism plays in science.

Skepticism is an essential part of the scientific method. New hypotheses must be able to withstand the close scrutiny of other scientists. The more radical the hypothesis, the more skepticism and critical evaluation it will receive from the scientific community, because the general rule in science is that extraordinary claims require extraordinary evidence.

What is the difference between a solar system and a galaxy?

Solar System= the star we call the Sun and all celestial bodies that orbit the Sun--including Earth, other planets, all their various moons and smaller bodies such as asteroids and comets Galaxies= huge assemblages of stars that are grouped together; our Sun is just one star in a galaxy we call the Milky Way; Typical galaxies contain several hundred billion stars; some galaxies are much smaller, containing a few million stars