Shared Flashcard Set

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Astro. Test 1
Chap 1./ First 2 lectures
15
Astronomy
Undergraduate 1
02/17/2009

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Cards

Term
What are models?
Definition
hypotheses that have withstood observational or experimental tests
Term
What are meteorites?
Definition
bits of interplanetary debris that sometimes fall onto our planet's surface; oldest objects found on Earth
Term
More massive stars have more/less nuclear fuel and live longer/shorter?
Definition
more; shorter
(they burn fuel much more quickly)
Term
Some dead stars can become pulsars. What are these?
Definition
rapidly rotating neutron stars
Term
What are quasars?
Definition
Distant extremely bright objects in sky
Term
What is the angular size of the moon? The sun?
Definition
1/2 a degree!
Term
When measuring distances across a solar system, what unit of length do astronomers use?
Definition
AU, parsec, light-year
Term
What is 1 AU?
Definition
The distance from the Earth to the Sun
Term
What is a light-year?
Definition
Distance that light travels in 1 year
Term
What is a parsec?
Definition
the distance at which 1 au subtends an angle of 1 arcsec, 3.26 ly
Term
Distance from Earth to Sun (in miles)?
Definition
93 million miles
Term
Distance from Earth to Moon (in miles)?
Definition
250,000 miles
Term
How many degrees is Earth's tilt?
Definition
23.5 degrees
Term
When are shadows longest? Why?
Definition
in wintertime, the sun is closer to the horizon so there is more sunlight spread out causing it to be colder than when the sun is farther away from the horizon causing the same amount of energy to be focused in a smaller space and thus hotter (with a smaller shadow)
Term
What is the distance away from every star in which scientists think life may occur?
Definition
zone of habitability
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