(A) Topic 1,2,3,4 wrong Flashcards
Define the term eclipse
When the shadow of a celestial body, such as the Earth or the Moon, obscures the light of another object in space
When do eclipses occur?
When the sun moon and earth are aligned with each other
Define the term ‘nodes’
points of intersection wherein the Moon’s orbit intersects the elliptic
Why do eclipses occur?
Occur because the bodies intersect each other
When do lunar eclipses take place
When the Moon passes through the Earth’s shadow, usually occurring during a full moon
What happens during the first contact in a lunar eclipse?
Moon enters earth’s penumbra
What happens during the second contact in a lunar eclipse
Moon moves into earth’s umbra.
Change in lunar surface colour due to refraction of sunlight caused by earth’s atmosphere
What happens during the third contact in a lunar eclipse?
Moon moves out of earth’s umbra
What happens during the fourth contact of a lunar eclipse?
Moon moves out of the earth’s penumbra
What happens during a partial lunar eclipse?
Earth’s shadow intrudes into Moon’s disc but doesn’t block it entirely
What occurs during an annular eclipse?
The appearance of a solar eclipse is that of a ring. Happens when the moon’s shadow is too small to cover the sun’s disc completely.
What is the line of totality?
the line on the Earth’s surface where the shadow is focused.
What happens during the first contact of a solar eclipse?
Moon becomes visible over the sun’s disc. sky darkens and temperature drops
What happens during the second contact of a solar eclipse?
the moon completely covers the sun’s disc. diamond effect and bailey’s beads produced. only sun’s corona is visible
What happens during the third contact of a solar eclipse?
Moon starts moving away, the sun reappears. Baileys beads and diamond effect produced again
What happens during the fourth contact of a solar eclipse?
Moon completely exits the sun’s disc. penumbra leaves
What causes precession?
Earth’s shape: oblate spheroid + the gravitational pull of the sun + moon. the gravitational pull of the sun and moon pulls on the earth’s equatorial bulge of which the west side gets pulled more (uneven), causing poles to move westwards along the elliptic
What is the precession of the equinoxes?
slight wobble in the earth’s axis every 26,000 years
Why do tides change their positions?
Moon is orbiting Earth, Earth rotates + water is attracted to and from Moon, Sun exerts a tidal force that is 40% that of the Moon.
What phase is the Moon in during Spring Tides?
Full + New Moon
What is the difference between Spring tides and Neap tides?
Spring tides: high tides are higher, low tides are lower
Neap tides: high tides are lower, low tides are higher
Why do the Sun and Moon appear to be the same size in the sky?
Moon is 400x smaller than the Sun, but the Sun is approx. 400x further away from Earth than the Moon.
How long is a day on the Moon?
27.3 Earth days
How big is the diameter + depth of Copernicus?
86km diameter, 4.8km depth
Why is Copernicus easy for astronomers to spot?
Slightly hexagonal shape + brighter than its surroundings
How big is the Ocean of Storms?
2500km
What is the Sea of tranquillity best known for?
Apollo landing site
What are valleys on the Moon?
Long depressions on the Moon’s surface
How are valleys thought to be formed?
Formed by ancient lava flows, collapsed lava tubes or geological faults
How are mountains on the Moon thought to be formed?
impacts which released under the early lunar surface
Describe the shape of a crater
Typically consist of a wall or rim, often have a central peak + slope leading to it
What are the poles?
A point 90 degrees from the equator.
Define prime meridian
Internationally agreed line of longitude from which measurements are taken. 0 degrees longitude
What is a tropic?
A region where the sun is directly overhead in the zenith at least once a year
Name the hottest part of the Earth and what element it’s composed of
Inner core: Iron
What purpose does daylight savings time serve?
So we have more time during the summer months
What is the difference between GMT and UTC?
UTC deviates to GMT by a second to account for earth’s rotation and is adjusted at times to account for leap seconds
What happens when you move to a time zone east of your original position?
You gain time
What happens when you move to a time zone west of your original position?
You lose time
How many meridians is the world split into?
24 meridians
Why did Harrison create the H4?
To tell time at sea
How would a sailor calculate the Lunar Distance method?
Measure the altitude of a prominent star above the horizon, and then observe the angle between the Moon and the star. Then consult an almanac (table of contents) to work out the longitude
Why does the Equinox change every year?
Due to precession, vernal equinox gets slightly earlier each year
What is a solstice?
When the day is at its longest/ shortest
What is an equinox?
When the sun passes over the celestial equator
Define ecliptic
Path the sun appears to take over the course of a year
Why do we have more daylight at different times of the year?
The daylight of a location on Earth receives depends on its position on earth, and the time or season of year
What is the difference between a sidereal month and a synodic month?
Sidereal: Moon orbits the earth with respect to the background star
Synodic: the period between the same phase of the moon
Why do moon phases occur?
Different amounts of sunlight reflected depending on moon’s position
What causes the sundial to be accurate during the year?
the earth’s axis (obliquity of the orbit) and the earth’s orbit
What are inaccuracies in apparent solar time caused by?
Caused by the earth’s elliptical orbit and axis of the earth.
Why is Earth’s rotational period 4 minutes less than 24 hours?
Earth’s axis of rotation is fixed with respect to the background stars, not the sun
