The Earth & The Solar System

Question 1

Define: perihelion.

Answer 1

The point where Earth is closest to Sun.

Question 2

Define: nadir.

Answer 2

Direction in which local gravity acts.

Question 3

Including the Earth, how many major planets are in our Solar System?

Answer 3

Eight.

Question 4

How long is one solar year?

Answer 4

365.24 days.

Question 5

What is the dominant factor affecting the seasons on the Earth?

Answer 5

The Earth’s axial tilt.

Question 6

What are the six major events in the solar calendar and when do they occur?

Answer 6

Perihelion: early January

March equinox: 20/21 March

June solstice: 20/21 June

Aphelion: early July

September equinox: 22/23 September

December solstice: 21/22 December

Question 7

Define: zenith.

Answer 7

Direction opposite to local gravity.

Question 8

Define: orbital period.

Answer 8

Time taken for a planet to complete one orbit.

Question 9

How else can we call the solar year?

Answer 9

Tropical year.

Question 10

What are the seven major latitudes?

Answer 10

N 90°: North Pole

N 66.5°: Arctic Circle

N 23.5°: Tropic of Cancer

N/S 00°: Equator

S 23.5°: Tropic of Capricorn

S 66.5°: Antarctic Circle

S 90°: South Pole

Question 11

Define: true horizon.

Answer 11

The apparent line that separates the earth and the sky.

Question 12

Define: ecliptic.

Answer 12

The plane in which the Earth orbits the Sun.

Question 13

Define: solar year.

Answer 13

Time taken for the Sun to return to the same seasonal position relative to the Earth.

Question 14

What is the Kepler’s Second Law?

Answer 14

A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

Question 15

What is the value of the Earth’s axial tilt?

Answer 15

23.5° away from being perpendicular to the plane of ecliptic.

Question 16

What is the Kepler’s First Law?

Answer 16

The orbit of a planet is an ellipse with the Sun at one of the two foci.

Question 17

Define: solstice.

Answer 17

Time of maximum difference between day and night lengths.

Continuous day at one pole, continuous night at the other.

Question 18

Define: aphelion.

Answer 18

The point where Earth is furthest from Sun.

Question 19

Define: astronomical horizon.

Answer 19

A plane through the eyes of the observer.

Question 20

How do we know if a year is the leap year?

Answer 20

It has to be divisible by four.

Exceptionally, a year is not a leap year even if it’s divisible by 4 if the it contains a whole hundred. This exception does not apply if the year is divisible by 400.

Question 21

What is the difference in degrees between the Tropics, and what does that signify?

Answer 21

47°. It is the amount the Sun travels during one Tropical (solar) year.

Question 22

Define: equinox.

Answer 22

Time of equal day and night lengths.

Sun overhead equator.

Both poles in constant daylight.