Earth, Sun, Moon Interactions Flashcards
Demonstrate why the sun and moon appear to be the same size as each other when viewed on earth
The diameter of the Sun is about 400 times larger than the Moon’s, but it is also roughly 400 times farther away from Earth.
What is the period of a lunar phase cycle
29.5 Days
Demonstrate an understanding of lunar phases and deduce the lunar phase cycle from given data.
New moon, Waxing Crescent, Half Moon, Waxing Gibbous, Full moon, Waning Gibbous, Half Moon, Waning Crescent, New Moon
Why is the lunar cycle 2.2 days longer than the moons orbit period
An extra 2.2 days is needed to bring the Moon, the Sun and Earth back into alignment and complete the lunar cycle.
Describe the appearance of partial and total solar and lunar eclipses.
Total- all of the sun/moon will beblocked out of view
Partial- bits of the sun/moon will be blocked out
Describe, using diagrams, the mechanisms causing solar and lunar eclipses.
- Sun & direction of sunlight
- Earth
- Moon
- Cones of shadow
- Area of umbra
- Area of penumbra
- Area of totality (if appropriate)
( practise drawing the eclipse )
Demonstrate an understanding that the duration of total solar and lunar eclipses are different and that they do not occur every new and full Moon.
Type of Eclipse Maximum Duration Solar (Total) 7 minutes, 30 seconds Solar (Annular) 12 minutes, 30 seconds Lunar (Total) 1 hour, 40 minutes
Sometimes they are aligned sometimes not
Describe the terms ̳solar day‘ and ̳sidereal day‘.
A solar day is the time taken for the Sun to move from its highest point in the sky back to its highest point the following day. This is exactly 24 hours.
A sidereal day is the time it takes for the Earth to actually rotate once on its axis. A sidereal day is four minutes shorter than a solar day.
Explain why a solar day is longer than a sidereal day.
The sidereal day is shorter than the solar day because as well as rotating on its axis, the Earth also orbits the Sun
Describe how a sundial can be used to determine time.
A sundial is a device that tells the time of day by the apparent position of the Sun in the sky. In the narrowest sense of the word it consists of a flat plate (the dial) and a gnomon which casts a shadow onto the dial. As the sun appears to move across the sky, the shadow aligns with different hour-lines which are marked on the dial to indicate the time of day.
Demonstrate an understanding that there are seasonal variations in the rising and setting of the Sun.
The Veranl Equinox in the Northern Hemisphere is during spring time however in the Southern Hemisphere it is during Autumn
Demonstrate an understanding of the terms ̳apparent Sun‘ and ̳mean Sun‘.
Sun time, or apparent solar time, is the time the Sun shows in the day. Normally we can make a sundial to tell this.
Mean solar time is the time on our watches that humans have invented as Sun time is an unreliable way to tell the time.
Because of the Earth’s elliptical orbit and the axis of Earth, apparent solar time as told on a sundial can be inaccurate to as much as 16 minutes. Apparent Midday on a sundial in Bristol will occur at a different moment to apparent Midday in London.
Demonstrate an understanding of the term ̳equation of time‘ (apparent solar
time — mean solar time) and perform simple calculations. This can be hard!
the difference between mean solar time (as shown by clocks) and apparent solar time (indicated by sundials), which varies with the time of year.
Describe aurorae and recall from where on Earth they are most likely to be observed.
These are spectacular displays of light and colour in the sky. In the northern hemisphere this is called Aurorae Borealis. In the southern hemisphere this is Aurora Australis. Most likely to be observed at the poles
Explain how aurorae are caused.
The particles that get caught in the Van Allen Belts then move along these field lines toward the magnetic north and south poles and observers in these location witness aurorae.
