Transcript 1. angular resolution

1. angular resolution
• ability to distinguish
between two adjacent
objects in the sky.
2. Cassegrain telescope -
• reflector telescope where
light is reflected back
through a hole in the center
of the curved mirror
3. charge-coupled device (CCD) -
• electronic device that
detects amount of light
hitting different pixels
4. chromatic aberration
• dispersion of light into its
colors by the prism-like
edges of lenses
5. coma -
• formation of tails on stars at
the edges of the field of
view, caused by improper
focus
6. focal length -
• distance from edge of mirror
or center of lens to the point
of the focus of light rays.
7. image -
• picture of object after
focusing by lens or mirror
8. Newtonian telescope -
• reflector where light is
reflected to the side near
the top of the telescope
9. prime focus -
• reflector telescope where
the image is viewed at the
point of focus of the main
reflector
10. radio telescope -
• reflector telescope which
only detects radio waves
11. reflector -
• telescope where light rays
are focused by reflecting
light at angles
12. refractor -
• telescope that focuses light
rays by bending them with
lenses
13. seeing disk
• the circle over which a star’s
light is spread due to
atmospheric blurring
1. How does a refracting
telescope focus light?
• A refracting telescope uses
a lens to bend light and
focus it at a point.
How does a reflecting telescope
focus light?
• A reflecting telescope uses
a curved mirror to focus light
at a point.
2. Why do all the world’s
largest optical
telescopes use the
reflector design?
Reflectors are used for four basic
reasons:
• (1) Lenses suffer from chromatic
aberration.
• (2) Lenses are opaque to IR and UV
radiation.
• (3) Large lenses are heavy, mirrors can be
supported across the back surface.
• (4) A lens has two surfaces that need to be
polished.
3. What advantages does the
Hubble Space Telescope have
over ground based telescopes?
• No atmospheric blurring.
What disadvantages?
• Must be serviced in space.
4. Why do radio telescopes
have to be extremely large?
• The radio waves to be
reflected are extremely long.
5. How does a radio telescope
work?
• The radio waves are
reflected to a central focal
point.
1. atmosphere -
• gaseous layer on the
surface of the Earth.
2. aurora -
• Light caused by
atmospheric particles being
excited by solar energy.
3. aurora australis
• Aurora at the south pole.
4. aurora borealis
• Aurora at the north pole.
5. basalt -
• Material that makes up the
crust under the oceans.
6. convection
• Circulation of fluids caused
by differences in density
due to differences in
temperature.
7. core -
• Hot center of the Earth;
made of iron and nickel.
8. crust -
• Thin surface of the Earth;
mostly made of granite on
the continents, basalt under
the oceans.
9. density -
• Mass divided by volume.
10. differentiation
• Separation of materials of
the Earth by density; most
dense in core, least dense
on surface.
11. dynamo theory -
• Convection currents in the
outer core combined with
the rotation of the Earth
produces the Earth’s
magnetic field.
12. exosphere -
• The outermost layer of the
Earth’s atmosphere
• (about 250 km).
13. granite -
• Material that makes up most
of the crust material at the
continents.
14. greenhouse effect
• The atmosphere of the
Earth traps much of the
heat re-emitted by the
surface.
15. hydrosphere -
• The water on the surface of
the Earth.
16. inner core -
• Central part of the core.
• Extremely hot (5000 K), but
compressed into a solid.
17. ionosphere -
• Atmospheric layer that is
very ionized.
• Conducts electricity.
• About 100 km.
18. lithosphere -
• Crustal plates and upper
mantle. Area that undergoes
tectonic activity.
19. magnetosphere -
• Area of charged particles
trapped by Earth’s magnetic
field.
20. mantle -
• Layer of Earth beneath the
crust.
21. mesosphere
• Layer of atmosphere from
50 - 90 km.
22. neap tide -
• Lower than normal tides
caused by the Sun’s gravity
pulling at right angles to the
Moon.
23. outer core -
• Outer part of the core.
• Very hot and liquid.
24. ozone layer -
• Atmospheric layer where
UV radiation is absorbed by
oxygen, ozone, and
nitrogen.
• (20 - 50 km)
25. plate tectonics
• Movement of crustal plates.
• Continental drift.
26. solar wind -
• Outward flow of charged
particles from the Sun.
27. spring tides -
• Higher than normal tides
caused when the Sun’s
gravitational pull is added to
the Moon’s because all
three are in line.
28. stratosphere -
• Atmospheric layer above
troposphere.
• 40 - 50 km.
29. thermosphere
• Layer of Earth’s atmosphere
above 90 km.
30. tidal bulge -
• Elongation of the Earth
caused by gravitational pull
of the Sun.
31. tides -
• Rising and falling motion
that bodies of water follow.
32. troposphere
• Atmospheric layer closest to
Earth.
• Up to 15 km.
• Weather.
33. Van Allen belts -
• Two donut-shaped regions
of magnetically trapped
charged particles high
above atmosphere.
1. By comparison with Earth’s
average density, what do the
densities of water and rocks in
Earth’s crust tell us about Earth’s
interior?
• Earth’s average density is 6
3
g/cm . Water and crust are
1 g/cm3 and 3 g/cm3.
Therefore, inner Earth must
be greater than 6 g/cm3.
2. Give a brief description of the
magnetosphere, and tell how it
was discovered.
• Area that is affected by the magnetic field
of the Earth, trapping charged particles
produced by the solar winds.
• Discovered by satellites launched in the
late 1950’s.
3. What process has created
the surface mountains, oceanic
trenches, and other large-scale
features on Earth’s surface?
• Plate tectonics.
4. How do we know that Earth’s
magnetic field has undergone
reversals in the the past?
• Study of the slight
magnetization of the areas
around the Mid-Atlantic
Ridge.