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.