1.1 Planet Earth Flashcards
(28 cards)
what is the average diameter of the earth?
the average diameter of the Earth is 13 000 km
what is the shape of the earth?
the Earth’s shape is an oblate spheroid
what is the longitude of a point?
the longitude of a point is the angle between the point on the Earth’s surface, the centre of the earth and a point on the equator
what are the latitudes of the poles?
the latitude of the poles are 90°N and 90°S
how much is the Earth’s polar axis tilted to the plane on which it orbits the Sun?
the Earth is tilted 66 1/2 degrees on the plane on which it orbits the Sun
what is the name of the plane on which the earth orbits the Sun?
the plane on which the Earth orbits the Sun is the ecliptic plane
on what dates are the spring and autumnal equinoxes?
the spring equinox falls on the 21st of March the autumnal equinox falls on the 22nd/23rd of September
what are the equinoxes?
the equinoxes are the name given to the phenomenon when the sun lies directly above the equator and they only occur twice a year
Tropic of ______ : 23 1/2°N
Cancer
Tropic of _______ : 23 1/2°S
Capricorn
what are the dates of the solstices?
the solstices fall on June 21st and December 21st
in terms of x, how is longitude expressed?
longitude is expressed x°E or x°W
in terms of x, how is latitude expressed?
latitude is expressed as x°N or x°S
how much of the Earth’s atmosphere is made up of nitrogen?
78% of the Earth’s atmosphere is made up of nitrogen
how far out is the generally-agreed Kármán line?
the Kármán line lies at 100km
what is the mean water temperature on earth?
15°C is the mean water temperature on Earth
why is the sky blue in day?
the reason that the sky appears blue is that gas molecules in the atmosphere ‘selectively scatter’ the shorter wavelengths of sunlight, making the sky appear blue.
what can most infared radiation be absorbed by? (3)
most infared radiation can be absorbed by water vapour, carbon dioxide and methane
X-rays and gamma rays are absorbed by what?
x-rays and gamma rays are absorbed by nitrogen
what is a refracting telescope?
a refracting telescope is a glass convex lens that collects the light and brings it to the surface
what is a reflective telescope?
a reflective telescope is a curved mirror which collects all the light rays
what type of telescope are most professional and large telescopes?
most professional telescopes are reflectors
what are the three disadvantages of orbiting telescopes?
the three disadvantages of orbiting telescopes are:
- reduced lifetime
- difficult or impossible maintenance/repairs/upgrades
- more expensive to build and launch into orbit
how are Van Allen belts held in place?
Van Allen belts are held in place by Earth’s magnetic field.
