Astronomy prologue-ch1
Terms
undefined, object
copy deck
- 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)