| Glossary -- left-click here :-) |
| Moon |
| What is light? |
It is electromagnetic radiation to which the human eye is sensistive. Light consists of either visible radiation or optical radiation |
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| Light |
| What is light? |
It is electromagnetic radiation to which the human eye is sensistive. Light consists of either visible radiation or optical radiation |
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| What is a light wave? |
It is the rising and falling of electromagnetic radiation, disturbance, that transports energy from a source to a receiver without the actual transfer of material. |
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| What is the wavelength? |
It is the distance between the crest and trough of a wave, and is measured in angstrom of which the unit is Å |
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Planets |
| Mercury has a crust consisting of light silicate rock with average density of about 3 times that of water. Then why has an overall average density of almost 5.5 that of water? |
Scientists believe that Mercury has a very dense core surrounded by a rocky crust. The core is believed to be about the size of our Moon. |
(Curtesy of Planetary Science Research Discoveries PSRD http://www.psrd.hawaii.edu/) |
| Despite the fact that Venus shares similarities with Earth in size, mass, density and distance from teh Sun, one could not live there. Why? |
1) Temperatures on Venus reach 482º;
2) the atmosphere is rich in the poisonous gas carbon dioxide;
3) the atmospheric pressure is 90 times that of Earth and it could crush anyone attempting to get near it. |
(Curtesy of NASA http://www.nasa.gov/) |
| Earth consists of three principal layers What are they? |
1)Crust, it extends to an average of 35km (22 miles) ;
2)Mantle, its thickness is about 2,880 km (1,800 miles);
3)the Core, that's about 3,470 kn (2,170 miles) deep. |
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| Stars |
| Stars on the celestial sphere appear to move during the night. Why? |
Because Earth is inside the celestial sphere and rotates on its axis . |
Celestial Sphere |
| Circumpolar constellations: which ones are the closest to Polaris (the North STar)? |
Cassiopea, Cepheus and Ursa Minor N.B. At latitude 40ºN, Ursa Major and Draco are also circumpolar. |
Circumpolar Stars |
| Stars on the celestial sphere appear to move during the night. Why? |
Because Earth is inside the celestial sphere and rotates on its axis . |
Celestial Sphere |
| Stars on the celestial sphere appear to move during the night. Why? |
Because Earth is inside the celestial sphere and rotates on its axis . |
Celestial Sphere |
| Calculate the distance the Sun makes on the ecliptic every day |
The Sun moves 360° around the ecliptic in 1 year
1 year=360 days
Therefore 360º ⁄365 days = 0.986 tha we can round up to 1º
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| There is a 4 minutes difference between a sidereal and solar day. What causes it? |
Earth's revolution around the Sun
1 year=360 days
Therefore 360º ⁄365 days = 0.986 tha we can round up to 1º
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| Stars appear to move along arcs, in the sky during the night. Why? |
Because Earth rotates.
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| Each season some different constellations appear in the sky. Why? |
This is due to Earth's revolution around the Sun.
1 year=360 days
Therefore 360º ⁄365 days = 0.986 tha we can round up to 1º
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| What is the zodiac? |
A band of sky that extends about 9° on either side of the ecliptic, and it contains 12 constellations.
1 year=360 days
Therefore 360º ⁄365 days = 0.986 tha we can round up to 1º
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| A solar day is about 4 minutes longer than a sidereal day, Why? |
While Earth rotates on its axis, it also orbits around the Sun, thus Earth completes a bit more than a whole turn in space before the Sun appears on the observer's meridian.
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| The Sun is passing directly across your zenith at the time of the vernal equinox. What your location on Earth would be? |
On the Equator'
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| The Sun is passing directly across your zenith at the time of the summer solstice. What your location on Earth would be? |
Tropic of Cancer, 23.5°N
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| The Sun is passing directly across your zenith at the time of the winter solstice. What your location on Earth would be? |
Tropic of Capricorn, 23.5°S
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