Test 1 Flashcards
What are constellations?
Groups of stars relatively close together in the sky.
Where on Earth can you stand and, over the course of a year, see the entire sky?
The equator.
Why do we only ever see the same side of the Moon?
The moon rotates once each orbit. Also known as tidal lock.
When the moon is at the Meridian at sunrise, it’s phase is what?
Third quarter.
If you see the first quarter moon on the Meridian, the sun is in what direction?
On the western horizon.
If people on earth were looking at a total lunar eclipse, what would you see from the moon?
A totally dark earth.
The cities of Beijing and Philadelphia have about the same latitude, how does their view of the sky compare?
They’re identical.
What star does the Earth’s axis point toward?
Polaris
What direction does the moon rise in?
The east.
What is the term for the a planet appearing to travel backwards as the Earth catches up to it?
Retrograde motion.
What are inferior planets?
Any that are closer to the Sun.
What are superior planets?
Any that are farther from the Sun.
Describe the speeds of planets with elliptical orbits.
They slow when they travel away from their star and speed up when moving towards it.
Describe Kepler’s second law.
A planet will move fastest when it is closest to it’s star.
What is one of the first public criticisms of the geocentric model?
Galileo’s observations of the phases of Venus and of moons orbiting Jupiter, indicating not all things orbit Earth.
Define eccentricity.
The stretch of a planet’s elliptical orbit.
Why are high eccentricity planets unlikely to support life?
The changing distance from the star drastically changes the temperature.
Which of Newton’s laws explains why people continue moving when a car stops.
Inertia.
Why do we wear seatbelts in cars and airplanes?
To protect against acceleration.
How would the speed of a satellite moving to a different orbiting altitude change?
Lower: faster, higher: slower
The connection between gravity and orbits enables astronomers to measure a planet’s what?
Mass.
How does the gravitational force change based on distance?
It is an inverse square. So a moon half as far would experience 4 times the force, while a moon twice as far would experience a fourth of the force.
Describe where the moon is during spring(vernal) and neap tides.
During spring tides it is in line with the Earth and the Sun, while during neap tides they form a right angle.
Self gravity is what?
The gravitational effect of all parts of a body.
Tidal tails are caused by…?
Gas on one side being pulled before the gas on the far side.
Astronauts experience weightlessness because…?
They are free falling around the Earth.
What kind of orbit is best represented by Kepler’s second law?
An elliptical orbit.
How long does it take light to reach the earth?
Roughly 8 minutes.
What is the term for the compression and elongation of frequencies?
The Doppler effect.
As a black body becomes hotter it also…?
becomes more luminous and bluer.
When a planet radiates less energy, what happens to the planet?
It’s temperature increases until equilibrium is achieved.
What happens when light enters a medium?
It slows down and refracts.
Star A is twice as far as Star B and equally as bright. How do their luminosities compare?
Star A is 4 times as luminous.
What does thermal equilibrium mean?
The amount of energy entering is the same as the amount leaving.
What does the negative number mean in Doppler shift calculations?
The star is moving closer to the observer.
What will doubling a star’s temperature do to it’s flux?
The flux will increase by 16 times as much.
Through what material does light travel fastest?
A vacuum.
What are some advantages of reflecting telescopes?
They have long focal length in a short tube; they don’t experience chromatic aberration; they don’t bend due to the weight of the lens; they don’t influence the light with a medium.
What is the purpose of adaptive optics?
To adjust a telescope to correct for light bending due to air turbulence.
What does better angular resolution mean?
Smaller details are visible.
What is the benefit of CCDs compared to normal photography?
They have higher quantum efficiency and see fainter objects.
What is the advantage of space telescopes over grounded?
They are unaffected by the atmosphere.
What are the different types of information gathering missions performed by probes?
Flybys - Travel past different planets, picking up data.
Rovers - land on ground and study the land matter.
Atmospheric probes - dip into the atmosphere of gas giants and send back data.
Why are all large telescopes reflective?
Chromatic aberration is minimized?
What is the biggest disadvantage for putting telescopes in space?
They are expensive to build and access for repairs.
