Exploring The Sky Flashcards
From what location on Earth can an observer see the centre of the Milky Way (RA 17h, Dec -29°)
In the southern hemisphere (negative declination) or any latitude North smaller than 60°
What is the best time of year to see Altair (RA 19h)
End of June
Menkar is 10 times fainter than Vega, if the apparent magnitude of Menkar is 2.53, what is the apparent magnitude of Vega
0.03
A space mission leaves Earth, when they see the sun 4 times fainter than it is seen on Earth, how far are they from the sun?
Twice the Earth-Sun distance
Why does the right ascension of the sun increase faster in January than it does in July?
Due to the eccentricity of the Earth’s orbit around the sun
What is true about the tropical year?
A - it is longer than the side real year
B - it is shorter than the eclipse year
C - it is the period from one vernal equinox to the next
D - it is the period of the earths orbit around the sun
C
In Kiev (50° N 30° E), when does the sun cross the local meridian relative to when it does in Greenwhich?
2 hours before
When does the sun, moving along the eclipse, cross the celestial equator moving from south to north?
The vernal equinox
If the mass of the moon were doubled, how would the gravitational attraction between the earth and the moon change?
It would be twice as strong
From earth when do we see Mercury moving with retrograde rotation?
At inferior conjunction (mercury between the earth and sun)
If Sirius has an apparent magnitude -1.46 and Spica has an apparent magnitude of 0.97, how much brighter if fainter is Sirius to Spica
10 times brighter than Spica
The best time to see Sirius (RA 6hr) is…
End of December
How often are the conditions met to see a solar eclipse somewhere on earth?
Every 173 days
What is the rotational period of the moon orbiting the Earth
The sidereal month
What is the maximum deviation of Solar time from the mean Solar time?
+- 15 minutes
If the earth-moon distance was twice as large then the gravitational attraction according to Newtons law would be….
A quarter as strong
A star orbited 2 exoplanets, the inner planet has an orbit with the radius 0.05AU and the outer has an orbit of the radius 1.50AU, from the outer planet how does the star appear?
900 times fainter than from the inner planet how does
How long is the sidereal year compared to the tropical year
Longer
In Lake Tahoe, 39° N 120° W, when does the sun cross the local meridian compared to Greenwhich time
8 hours after
When looking at Orion, it is covered by an outstretched hand held at arms length, what is it angular extent?
18°
What of the following does the celestial equator pass through?
A - Canis Major
B - Orion
C - Ursa Major
D - Ursa Minor
B
Who introduced the scheme of specifying the brightness of a star by its magnitude?
Hipparchus
What if the following does the ecliptic pass through?
A - Canis Major
B - Aries
C - Ursa Major
D - Ursa Minor
B
What is the period of the precession of the equinoxes?
26,000 years
When does a Lunar eclipse happen?
When the Earth is between the Sun and the Moon
When is a superior planet best observed at?
Opposition
Keplers third law states that the square of a planets orbital period is proportional to which power of its semi major axis?
Third
What did Einstein’s theory of relativity explain?
The orbit of Mercury
