Exploring The Sky

Question 1

From what location on Earth can an observer see the centre of the Milky Way (RA 17h, Dec -29°)

Answer 1

In the southern hemisphere (negative declination) or any latitude North smaller than 60°

Question 2

What is the best time of year to see Altair (RA 19h)

Answer 2

End of June

Question 3

Menkar is 10 times fainter than Vega, if the apparent magnitude of Menkar is 2.53, what is the apparent magnitude of Vega

Answer 3

0.03

Question 4

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?

Answer 4

Twice the Earth-Sun distance

Question 5

Why does the right ascension of the sun increase faster in January than it does in July?

Answer 5

Due to the eccentricity of the Earth’s orbit around the sun

Question 6

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

Answer 6

C

Question 7

In Kiev (50° N 30° E), when does the sun cross the local meridian relative to when it does in Greenwhich?

Answer 7

2 hours before

Question 8

When does the sun, moving along the eclipse, cross the celestial equator moving from south to north?

Answer 8

The vernal equinox

Question 9

If the mass of the moon were doubled, how would the gravitational attraction between the earth and the moon change?

Answer 9

It would be twice as strong

Question 10

From earth when do we see Mercury moving with retrograde rotation?

Answer 10

At inferior conjunction (mercury between the earth and sun)

Question 11

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

Answer 11

10 times brighter than Spica

Question 12

The best time to see Sirius (RA 6hr) is…

Answer 12

End of December

Question 13

How often are the conditions met to see a solar eclipse somewhere on earth?

Answer 13

Every 173 days

Question 14

What is the rotational period of the moon orbiting the Earth

Answer 14

The sidereal month

Question 15

What is the maximum deviation of Solar time from the mean Solar time?

Answer 15

+- 15 minutes

Question 16

If the earth-moon distance was twice as large then the gravitational attraction according to Newtons law would be….

Answer 16

A quarter as strong

Question 17

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?

Answer 17

900 times fainter than from the inner planet how does

Question 18

How long is the sidereal year compared to the tropical year

Answer 18

Longer

Question 19

In Lake Tahoe, 39° N 120° W, when does the sun cross the local meridian compared to Greenwhich time

Answer 19

8 hours after

Question 20

When looking at Orion, it is covered by an outstretched hand held at arms length, what is it angular extent?

Answer 20

18°

Question 21

What of the following does the celestial equator pass through?

A - Canis Major
B - Orion
C - Ursa Major
D - Ursa Minor

Answer 21

B

Question 22

Who introduced the scheme of specifying the brightness of a star by its magnitude?

Answer 22

Hipparchus

Question 23

What if the following does the ecliptic pass through?

A - Canis Major
B - Aries
C - Ursa Major
D - Ursa Minor

Answer 23

B

Question 24

What is the period of the precession of the equinoxes?

Answer 24

26,000 years

Question 25

When does a Lunar eclipse happen?

Answer 25

When the Earth is between the Sun and the Moon

Question 26

When is a superior planet best observed at?

Answer 26

Opposition

Question 27

Keplers third law states that the square of a planets orbital period is proportional to which power of its semi major axis?

Answer 27

Third

Question 28

What did Einstein’s theory of relativity explain?

Answer 28

The orbit of Mercury