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29 Cards in this Set

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fixed in space with respect to Earth's axis and Sun's direction at vernal equinox
celestial coordinates right ascension and declination
We would be more likely to get an accurate measurement of the distance from Earth to a nearby star if we took the angular measurements at times separated by what time interval?
6 months apart
A star overhead will move through what angle in the course of one hour?
15 degrees
What is the primary observable effect of the slow precession of Earth's rotational axis?
It causes the set of constellations visible on any fixed night each year to change over many years.
What distance would light travel through empty space in one year?
about 10 trillion kilometers (1012 km)
Why are the stars Betelgeuse and Rigel also known as alpha and beta Orionis?
They are the two brightest stars in the constellation Orion
Night and day have approximately equal length at what time or times of the year?
vernal and autumnal equinoxes
What is the length of time needed for the Earth's rotation axis to complete one cycle of precession?
26,000 years
How much longer is one solar day on Earth than one sidereal day?
3.94 Minutes
What is longer, a solar day or siderial day?
A solar day
1 * 10^9 is how long?
50 years
how long is 1 * 10^6?
2 weeks at 16 hrs a day
how long is 1000?
16 minutes
how is the astronomical perspective measured?
scientific notation
What is a light year?
the distance that light travels in one year with a speed ~3000,000 km/s = 3*10^5 km/s
how many constellations are there?
88 total
who named the constellations?
Greeks
Constellations
human nature to group things
revolution
365 days
rotation
1 day
Right Assension and Declination
can find any star (object) at any time
how long is a solar day?
24 hours
how much does the earth rotate during a solar day?
360.986 degrees
how long is a sidereal day
3.9 minutes shorter than a solar day
what does greek "sidus" mean?
star
what does day mean?
period
a sidereal day means
of time to rotate once relative to the background stars.
equation for distance?
360*baseline
_____________ =r
2 (pi) * parallax
equation for diameter? (baseline)
2(pi)r*parallax
--------------- = baseline
360 (degrees)