The Earth & The Solar System Flashcards
Define: perihelion.
The point where Earth is closest to Sun.
Define: nadir.
Direction in which local gravity acts.
Including the Earth, how many major planets are in our Solar System?
Eight.
How long is one solar year?
365.24 days.
What is the dominant factor affecting the seasons on the Earth?
The Earth’s axial tilt.
What are the six major events in the solar calendar and when do they occur?
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
Define: zenith.
Direction opposite to local gravity.
Define: orbital period.
Time taken for a planet to complete one orbit.
How else can we call the solar year?
Tropical year.
What are the seven major latitudes?
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
Define: true horizon.
The apparent line that separates the earth and the sky.
Define: ecliptic.
The plane in which the Earth orbits the Sun.
Define: solar year.
Time taken for the Sun to return to the same seasonal position relative to the Earth.
What is the Kepler’s Second Law?
A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
What is the value of the Earth’s axial tilt?
23.5° away from being perpendicular to the plane of ecliptic.
What is the Kepler’s First Law?
The orbit of a planet is an ellipse with the Sun at one of the two foci.
Define: solstice.
Time of maximum difference between day and night lengths.
Continuous day at one pole, continuous night at the other.
Define: aphelion.
The point where Earth is furthest from Sun.
Define: astronomical horizon.
A plane through the eyes of the observer.
How do we know if a year is the leap year?
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.
What is the difference in degrees between the Tropics, and what does that signify?
47°. It is the amount the Sun travels during one Tropical (solar) year.
Define: equinox.
Time of equal day and night lengths.
Sun overhead equator.
Both poles in constant daylight.
