astro 101 ch1-4
Why is the Hubble Space Telescope in space instead of on the ground?
-It avoids atmospheric distortion. -observes in the UV
The largest astronomical refractor has an aperture of 1 meter. Select all true statements below about why it would be impractical to build an even larger refractor with, say, twice the aperture.
-The degree of chromatic aberration increases as the focal length gets longer, and this would reduce image quality. -A lens with a 2 m diameter would be very heavy and would deform under its own weight within a few years. -The tube would have to be so long that housing and moving it would be extremely difficult, especially because it would be frontloaded with weight.
Based on the time frames given in the above figure, which of the following are implications of the finite speed of light?
-There would be a noticeable delay in communications at the speed of light between Earth and astronauts on the Moon. -When we gaze at the Andromeda Galaxy, we are looking back in time to the way it used to appear millions of years ago. -If the light of the Sun were suddenly extinguished, we wouldn't notice it from Earth for over 8 minutes.
A net force must be acting when an object (select all that apply):
-changes speed and direction. -accelerates. -changes direction but not speed. -changes speed but not direction.
The tilt of Earth's axis causes the seasons because
-days are longer in summer -rays of light strike the ground more directly in summer
Which stars we see at night depends on
-time -earth location in orbit -our location on earth
Which of the following can be observed from Earth's surface?
-visible light -radio waves
What causes the angle of the Sun to change over the year?
Earth's North Pole always points in the same direction in space. Sometimes this is toward the Sun, and sometimes it's away from the Sun.
Suppose you read on the Web that a new planet has been found. Its average speed in its orbit is 33 kilometers per second (km/s). When it is closest to its star, it moves at 31 km/s, and when it is farthest from its star, it moves at 35 km/s. This story is in error because
Kepler's second law says the planet must move fastest when it is closest, notwhen it is farthest away.
Besides adding adaptive optics to a telescope, what else can be done to reduce the effects of seeing?
Put the telescope at a higher altitude (the height above sea level).
Suppose you lived on the planet named "Tau Ceti e" that orbits Tau Ceti, a nearby star in our galaxy. How would you write your cosmic address?
Tau Ceti e Tau Ceti Milky Way Galaxy Local Group Virgo Supercluster Universe
Label these important reference points in your sky.
south > meridian > Zenith (above head) > East
How does the heliocentric model explain the retrograde motion of Mars?
The heliocentric model explains retrograde motion because Mars only appears to move backward as Earth passes it in its orbit around the Sun.
Which is not true about the vernal and autumnal equinoxes?
The motion of the stars in the sky on the equinoxes is different than on other days.
We always see the same side of the Moon because
the Moon rotates once each revolution.
Astronauts in a space shuttle can float while orbiting Earth. Why are these astronauts weightless?
They are falling around Earth at the same rate as the shuttle.
Based on the seasonal views of the sky in the diagram shown, is it more likely to be summer or winter when the following constellations are visible? (For the purposes of this problem you may ignore the fall and spring views.)
Winter (Orion, Canis Major) Summer (Scorpius Cygnus) Need more info (Ursa Major, Pegasus)
A light wave does not require:
a medium.
For a system in which a planet orbits a star, the center of mass is located
along the line between the planet and the star, closer to the star.
A light-year is a measure of
distance
Rank the given objects in order of increasing size. You may need to use the arrows on the side to scroll to see all of the images.
earth < solar system < milky way < local group < supercluster
The following astronomical events led to the formation of you. Place them in order of their occurrence over astronomical time.
hydrogen/helium created in big bang > stars are born > stars die > Dust/gas gather into clouds > sun/planets form
Occam's razor states that
if two hypotheses fit the facts equally well, choose the simpler one.
Suppose you are transported to a planet with twice the mass of Earth, but the same radius of Earth. Your weight would __________ by a factor of __________.
increase; 2
The connection between gravity and orbits enables astronomers to measure the __________ of stars and planets.
masses
Drag each label denoting length of time it takes light to travel from one location to another to the correct target.
moon to earth (1.2 sec) earth to sun (8.5 min) pluto to nearest star ( 4.3 years) length of milky way (100k years)
The cosmological principle states that
on a large scale, the universe is the same everywhere at a given time.
Place the following in order from largest to smallest semimajor axis:
planet with a period of 2 earth years > 1 earth year > 0.5 years > 84 days
The advantage of an interferometer is that
the resolution is dramatically increased.
The fact that scientific revolutions take place means that:
the science we know now is more correct than it was in the past.
When a ball is tossed in the air and reaches the top of its arc, which of the following quantities are zero?
velocity, speed
