(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