Download 1. Titius-Bode Law --

1. Titius-Bode Law -• A general guide to the distances of the
planets from the Sun.
• Oversimplified, each planet’s orbit is twice
as far from the Sun as the previous
planet’s orbit.
2. albedo -• The fraction of incident sunlight that is
reflected by an object into space.
• Mercury’s albedo is 0.1.
• Venus’ is 0.7.
3. transit -• A smaller, darker object passing in front of
a larger, brighter one.
• Mercury and Venus transit the Sun.
4. scarp -• A cliff.
• This feature is found on Mercury, but not
on the Moon.
5. Caloris Basin -• An immense crater on Mercury formed by
the impact of a large asteroid.
6. Weird terrain -• A ripply and wavy surface feature on
Mercury on the opposite side from the
Caloris basin.
1. Why is Mercury only
observed when on the horizon?
Since Mercury is closer to the
Sun than the Earth, it is always
observed in the same direction
as the Sun. Therefore, when
visible, it is only visible
immediately before sunrise or
after sunset. When it is any
higher in the sky, it is obscured
by sunlight.
2. What is a transit?
• When a small, dark object crosses over a
larger, brighter object.
3. How does Mercury’s size
compare with the other planets?
• Mercury is the second smallest of the nine
planets. It is only a little larger than
EarthÕs Moon.
4. Tell two surface features
found on Mercury that are not
found on the Moon.
• Scarps – cliffs
• “Double-ringed craters”
5. How do Mercury’s daytime
and nighttime temperatures
vary?
• Daytime temperatures can reach as high
as 700K. Nighttime temperatures are
about 100K.
• This 600K temperature range is the largest
of any planet or moon in the solar system.
1. morning star -• Venus’ “nickname” when viewed in the
morning sky.
2. evening star -• Venus “nickname” when viewed in the
evening sky.
3. Sirius -• The brightest star in the sky.
• Venus is 10 times brighter than this star.
4. superior conjunction -• When Venus and the Earth (or Mercury
and the Earth) are on opposite sides of the
Sun.
5. inferior conjunction
• When Venus and the Earth (or Mercury
and the Earth) are on the same side of the
Sun.
6. Mariner -• Space exploration series sent by the
United States to Venus and Mercury.
7. Venera -• Space exploration series sent by the
Soviet space program to Venus.
• Many Venera soft landed on the surface of
Venus.
8. retrograde rotation -• Venus rotates on its axis in a clockwise
direction when viewed from celestial north.
• This is opposite its direction of revolution
and the direction of rotation of most other
planets.
9. Ishtar Terra -• Extensive highland region in the northern
hemisphere of Venus.
10. Aphrodite Terra -• Extensive highland region along the
equator of Venus.
11. Cleopatra crater -• Large, meteoric crater on the Ishtar Terra.
12. shield volcano -• Volcano formed over long periods of time
by successive eruptions and lava flows.
• Most common type on Venus.
13. caldera -• Crater at the summit of a shield volcano
formed when the center of lava recedes.
14. coronae -• Huge, roughly circular volcanic regions on
Venus.
15. basalt -• Type of rock produced by volcanic activity.
• Most rock tested on Venus is basaltic.
16. granite -• Crust-like rock.
• Some rock on Venus is granite.
1. Why were Mercury and
Venus each thought to be two
separate celestial objects at
first?
Each planet was only seen near
the western horizon in the
evening sky, and near the
eastern horizon in the morning
sky, and NEVER seen higher in
the sky.
2. How does Venus’ orbital
period relate to its rotational
period?
Venus’ orbital period is 225
Earth days.
Venus’ rotational period is 243
Earth days.
A day is longer than a year.
3. What is extremely unique
about Venus’ rotation on its
axis?
• Venus rotation is retrograde. Opposite its
direction of revolution.
4. Why did all Soviet Venera
soft-landers on Venus cease to
function within one hour of
landing?
The surface temperature of
Venus is 750K and the surface
pressure is 90 times that of
Earth.
The Venera landers were either
cooked or crushed.
5. What gas makes up most of
Venus’ atmosphere? How does
this affect surface temperature?
Carbon dioxide - 96.5%. This
causes a Greenhouse Effect
absorbing 99% of the infrared
radiation released from the
surface of Venus.
6. Why is Venus called Earth’s
sister planet?
• Aproximately the same size. The same
basic composition.
8. Does Venus have volcanic
activity today? How do we
know?
It is believed that Venus still has
volcanic activity. Sulfur dioxide
levels fluctuate greatly. Bursts
of radio energy are observed
which are similar to lightning
charges around volcanos on
Earth. However, no erupting
volcano has yet been detected.
9. Do other planets besides
Mercury and Venus observably
transit the Sun as viewed from
Earth? Why?
No. The other planets have
orbits outside the Earth’s. Only
Venus and Mercury can EVER
move to a position between
Earth and the Sun.
10. Why does Mercury transit
the Sun more frequently than
Venus?
• Venus is farther from the Sun and the
proper alignment occurs less frequently.
11. Describe one surface
feature that is unique to Venus.
• Coronae - Huge,roughly circular volcanic
structures. Apparently caused by
upwelling mantle material.
12. How does the brightness of
Venus compare to other celestial
objects?
• Venus is the third brightest object in the
sky. It is 10 times brighter than the
brightest star (Sirius).