The Solar System

Question 1

Ecliptic

Answer 1

Earth is tilted on its axis at 23.5 degrees.
Therefore, through the year, the position of the sun relative to the equator varies between 23.5 S and N, called the Ecliptic.

Question 2

Seasons

Answer 2

Due to the tilt of the earths axis with the plane of the equator at an angle of 23.5 degrees. If there was no tilt, no seasons.

Question 3

Orbit direction

Answer 3

Anti clockwise in an elliptical shape.

Question 4

Obliquity of the ecliptic

Answer 4

Angle between the earths celestial equator and the plane of ecliptic.

Question 5

Apparent ‘real’ movement

Answer 5

Always in the plane of ecliptic, between 23.5 degree N and S.

Question 6

Keplers first law

Answer 6

Orbit of a planet describes an ellipse , with the sun at one focus.

Question 7

Keplers second law

Answer 7

A line joining any planet to the sun sweeps out equal area in equal time.

Question 8

Perihelion

Answer 8

Fastest orbital velocity.
3rd January.

Question 9

Aphelion

Answer 9

Slowest orbital velocity.
3rd July.

Question 10

Axial tilt

Answer 10

Axis of rotation is tilted approximately 23.5° away from being at right angles to the plane of the ecliptic. Now between vertical and new line.

Earth’s axis of rotation is inclined to its orbital path around the sun
at an angle of 66.5 degrees.

This determine amount of sun light received.

Question 11

No axial tilt

Answer 11

Equal day and night.

Look around the orbit at any point and would find a point where the axis would be at right angles to a line between Earth and the Sun.

Question 12

Northern hemisphere summer on June 21st

Answer 12

-From N64.5 to North Pole is continuous daylight.
-N66.5 is called Artic circle.
-Sun will not set at any time of year above these latitudes.
-At midday sun is directly overhead Tropic of Cancer 23.5N.
-length of night increases the further south you go.
-S66.5 called Antarctic circle.
-S66.5 to South Pole night time is continuous.

Question 13

Southern hemisphere summer on December 21st

Answer 13

Exact same as Northern Hemisphere but for southern.

Question 14

The solstices

Answer 14

Two points where the sun has either:
-Reached its northernly limit and stops moving north
-Reached its southerly limit and stops moving south
-Northern solstice = 20th/21st June
-Southern solstice = 21st/22nd December

Question 15

The equinox’s

Answer 15

When the sun is directly overhead the equator, daytime and nighttime are equal:
-One occurs in March, 20th/21st.
-One occurs in September, 22nd/23rd.

The equinoxes - when the declination of the sun is 0 as it is above the equator.

Question 16

Declination (latitude) of the sun.

Answer 16

The suns declination is the suns position relative to the plane of the equator. When the declination of the sun is 0 degrees, the sun is directly above the equator - the rate of change of daylight is greatest.

Question 17

Orbital period

Answer 17

A leap year is every 4 years unless the year is a hundred unless it’s a 400.

Question 18

Apparent solar day

Answer 18

An apparent solar day is measured against the real or ‘apparent’ sun.
The sun as it actually appears to an observer on the surface of the earth.
– Using the apparent sun introduces the problem of the apparent solar day not being a constant length.

Question 19

Mean solar day

Answer 19

A mean solar day is the length of an apparent solar day averaged out
throughout the year.
– It is of constant length - 24hrs - and is divided into hours, minutes and seconds of ‘mean’ time.

Question 20

Mean sun

Answer 20

The mean sun is assumed to travel at a constant angular velocity in the plane of the equator.

‘Mean’ implies it is constantly located overhead the equator.