Chapter 21 Inner Planets
Because of Mercury's eccentric orbit, maximum separation of 28° from the Sun can only happen when...?
... when the Earth-Sun line is perpendicular to the long axis of Mercury's orbit and Mercury is near aphelion (farthest from Sun).
Venus's Mass
.78 of the Earth's
Venus's Volume
.81 of the Earth's
Venus's Radius
.95 of the Earth's
Mercury's Day v Year?
1 Mercury Day= 59 Earth days 1 Mercury Year= 88 Earth days Days & years are in a 3:2 resonance (rotates 3x during 2x around sun)
Mercury's Magnetic field
1% as strong as Earth's
Mercury transits the Sun
13-14 times every century
How long does it take venus to orbit the sun?
225 earth days
Mercury's Size in Diameter
3025 miles
Mercury's Distance from the sun
36 million miles
Venus's Average Density
5300 kg/m^3
Mercury's Rotational Period
58.65 days
Mercury's rotation rate
59 days
Venus's Temperature
730 K
Mercury's Orbital Period
88 days
Venus's atmosphereic pressure
90 times the Earth's
Mercury and its phases are most visible at...
Aphelion (farthest point from Sun). Otherwise, its too close to the Sun & the horizon.
Venus's largest highlands
Aphrodite Terra
Why does Mercury have extreme temperature variations?
Because it has not magnetic fields and no atmosphere
How can the age of Mercury's craters be found?
By counting craters on the ejecta blankets after the original impact.
Large impact crater on Mercury
Caloris Basin
Mercury's Largest feature photographed by Mariner 10 probe
Caloris Basin
What is "weird terrain" and what formed it?
Caloris basic impact - focus of the seismic waves reached other side of planet creating weird terrain
Venus's atmosphereic Chemical Composition
Carbon Dioxide- 95.3% Nitrogen- 3.5%
What creates Mercury's almost non-exhistant atmosphere?
Charged particles blasts atoms off of Mercury's surface.
Mercury's Dominant surface feature
Craters
Is Mercury more or less dense than the Moon?
Denser than the Moon.
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. Radius: 3,959 miles (6,371 km) Age: 4.54 billion years Mass: 5.972E24 kg Distance from Sun: 92,960,000 miles (149,600,000 km), 1 AU Area: 196,900,000 sq miles (510,100,000 km²) Gravity: 9.8 m/s²
What is Mercury's surface most like?
Earth's Moon
Why is Mercury's high density odd?
High density usually means there is a big, metal core. BUT even though the core must be slow and therefore hardened, Mercury has a magnetic field, which would mean that the core is liquid.
Venus's highland containing Maxwell montes
Isthar Terra
Mercury has not atmosphere, but what comet-like feature does it have sometimes?
It has a tail formed by solar wind that is made of sodium
Why can't we easily see Mercury from Earth?
It is almost always blocked by sunlight
Venus's Probes
Magellan (orbiting)
Used radar imaging to map the surface of the planet Venus
Magellan probe
Mars
Mars is the fourth planet from the Sun and the second smallest planet in the Solar System. Named after the Roman god of war, it is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance. Radius: 2,106 miles (3,389 km) Surface area: 144,800,000 km² Distance from Sun: 141,600,000 miles (227,900,000 km) Gravity: 3.711 m/s² Length of day: 1d 0h 40m Moons: Phobos, Deimos
Is Mercury more or less cratered than Moon?
Mercury is less cratered than the Moon.
Mercury
Mercury is the innermost planet in the Solar System. It is also the smallest, and its orbit is the most eccentric of the eight planets. It orbits the Sun once in about 88 Earth days, completing three rotations about its axis for every two orbits. Radius: 1,516 miles (2,440 km) Distance from Sun: 35,980,000 miles (57,910,000 km) Surface area: 74,800,000 km² Length of day: 58d 15h 30m Density: 5.43 g/cm³ Orbits: Sun Gravity: 3.7 m/s²
3-to-2 spin coupling
Mercury's rotation: the planet spins three times every 2 revolutions around the sun
Is Mercury Tidally Locked?
NO. Proved by 3:2 resonance of days & years (not equal)
Does Mercury have radiation belts, like our Van Allens?
No.
Magnetic field of Venus
None
How did scientist measure the rotation rate of Mercury?
Pulsed radar to Mercury detected return from signal, used Doppler Effect
What was responsible for the blank spots on Mercury in pics taken by Mariner 10?
Scarps. The Mariner 10 passed a giant scarp when the sun was directly overhead, so the scarp didn't cast any shadows, leaving that part of the surface too bright to capture.
Venus's Unusual Motion
Slow retrograde rotation
What created Mercury's "weird terrain?"
The Caloris impact. Seismic waves went all the way around the planet & collided on the opposite side of impact.
Moon
The Moon is the only natural satellite of the Earth, and the fifth largest satellite in the Solar System. Wikipedia Distance to Earth: 238,900 miles (384,400 km) Gravity: 1.622 m/s² Orbital period: 27 days Age: 4.527 billion years Declination: 28° 0.000' Orbits: Earth
What is special about Mercury's core?
The planet has a huge core (70%) and a very small mantle before the surface
Mercury's named for
The winged messenger of the gods in Roman Mythology
Strength of Mercury's tidal forces? What are they from?
Tidal forces are very strong b/c of closeness to the Sun (so more on Sun-facing side).
Venus's Landers
Venera I&II
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after the Roman goddess of love and beauty. Radius: 3,760 miles (6,052 km) Distance from Sun: 67,240,000 miles (108,200,000 km) 0.723 327 AU Surface area: 460,200,000 km² Length of day: 117d 0h 0m Gravity: 8.87 m/s² Mass: 4.867E24 kg (0.815 Earth mass)
Mercury's Eccentricity?
Very circular: 0.206
Mercury's Albedo?
Very low & unreflective: 0.12
Does ice form on Mercury?
Yes, some ice forms in cool shadows in craters
what is there near the poles of Venus
a huge hurricane-like vortex
Venus underwent a global repaving event involving what
a large amount of tectonics or volcanism or both
Why is Venus called the morning or evening star?
because it is tied to the sun and only seen at those times
Mercury's Sky's color
black
Reflectivity of Venus compared to other planets
brightest
Mercury' location on the Solar System
closest planet to the sun
How did we know that Venus had water
comparing the relative abundance of hydrogen isotopes on Venus and Earth
Venus's Weather
constant cloud cover
Characteristics of Mercury's interior
cool, iron-rich core
When Mercury is seen best
during the day(from space) when it's highest in the sky
What is venus called in relation to earth?
evil step sister
why is Venus so hot
greenhouse effect, due to lots of CO2
What we're learned from Mariner 10
heavily cratered (intercrater plains[similar to the moons maria]), has scarps(long cliffs that appear to be cracks that formed from as the surface cooled and contracted), Caloris Basin(ring of mts.), hilly terrain(opposite Cal. B.), possibility of water ice, information on the interior
Characteristics of Mercury's orbit
highly elliptical, inclined plane
Venus
hotter, brighter than mercury. bigger, closer to earth, and clouds are reflective
On Mercury the smoothed surface regions possibly from lava flow covering the craters
intercraterplains
What is special about venus?
it rotates on its axis the opposite way of every other planet. it takes it longer to to make a complete rotation than it does to orbit the sun. aka. its day is longer than its year
Unusual hilly formation on opposite side of the planet from Caloris Basin on Mercury
jumbled terrain
Venus's Interior
large, hot, iron-rich core
characteristics of Venus' interior
large, hot, iron-rich core
Mercury's internal structure
mantle and HUGE iron core(75% of its diameter)
Largest mountain on Venus (shield volcano)
maxwell montes
Characteristics of Mercury's atmosphere
no atmosphere
Mercury's Atmosphere
none
Moons of Venus
none
Venus's Magnetic Field
none
Venus's Moons
none
Where is venus at superior conjunction?
opposing side of sun from the earth
What about Venus is similar to earths?
radius, mass, and density
Giovanni Schiaparelli
rotation rate first measured by observing faint features on the surface, he got it wrong b/c he observed every third greatest eastern or western elongation which would mean that he always views the same side and therefore concluded that Mercury's orbit was synchronous
Through what process did Venus heat up
runaway greenhouse
Huge cliffs on Mercury thought to have formed as the planet cooled and contracted
scarps
Mercury's size in relation to others in the solar system
second smallest
Mariner 10
the only space craft to be sent to Mercury
What is the brightest planet in the sky?
venus. (3rd brightest object to the sun and moon)
Temperature of Mercury
very hot in the day 700k (it has three earth months to heat up) and the nights are extremely cold 100k
Venus's What does Venus still have in geological terms
volcanism
What kind of magnetic field does Mercury have
weak
When does venus appear to be brightest?
when a cresent about 39 degrees from the sun
When is venus at inferior conjunction?
when it lies closest to earth. in between sun and earth
What are Mercury's "Scarps"?
• Cliffs on Mercury's surface. • Formed when crust cooled & contracted, creating creases.
The Mariner 10 & Mercury?
• First probe to use "gravitational slingshot" • Mapped 1/2 of Mercury's surface (sunlight+"rupes" hid other part) • Discovered the thin atmosphere & magnetic field
What role did the Messenger have with Mercury?
• It photographed Mercury's blank spots. • It discovered volcanoes on Mercury.
What is it about Mercury's core?
• It's the biggest core in the solar system • It can focus seismic waves on the opposite side of the planet from impact sites. • It must be liquid metal.
Does Mercury have volcanoes? How are they identified?
• Yes; now inactive volcanoes exist on Mercury's surface. • Volcanic vents create irregularly-shaped depressions. • Dome-like features marks the outer limits of lava flows from vents. • The double outlines of bright material are deposits ejected during eruptions. • Impact craters were filled up with lava flow.
