Jerry Oltion, Solar System Tour

Same disclaimer. Raw notes. Coherence is random.

Until we have FTL most stories about humans in space will happen in our own solar system. Even when we send people out, it’s probably a good idea to understand the local real estate.

(Jerry still includes Pluto as a planet. “Poor thing, it gets no respect.”)

Mnemonic to remember the order of the planets. “Mother Very Easily Made Jelly Sandwiches Under No Provocation.”

I’m going to put the rest behind a cut, because I took a lot of notes on this one.

Sun

The sun is an average star — a little bit misleading. The numeric average is dimmer and redder but when people say it’s average they mean that there’s nothing unusual about it.

Coronal mass ejection – Ionized gas ((hydrogen and helium)) that the sun burps out in greater quantities than usual. We get amazing auroras if they are aimed at us. Some CMEs can disrupt satellites or cause surges and have even caused blackouts.

Sunspots are often bigger than the Earth. Individual granules are about the size of Texas. Sunspots are mostly a magnetic effect. The magnetic field is coming out in one sunspot and popping back in at a different sunspot. So they tend to come in pair. It’s a magnetic weather storm on the sun that comes in eleven year cycles. We’re just going into a new sunspot activity which will cause more satellite issues, but not anything we really need to worry about in terms of health or environment.

Living On (or Near) the Sun (If you have a human character there)

• Really, really big. Not much in the way of landmarks.
• Really, really hot (58000degrees K)
• No solid surface
• High gravity (28g)
• Serious radiation and magnetic effects
• Solar panels would be very efficient! (on the other hand, the excess heat is a problem)
• Hard to reach (4 times harder than Earth orbit)
• Hard to leave gravity well (light sails?)

Mercury

Will never see Mercury late at night. Only sunrise or sunset. If you stretch your hand out so that the thumb covers the sun. Mercury will be about where your little finger is.

Mercury has double-ring craters. Not sure why.

The South Pole is the best real estate. Mercury has no orbital tilt. So the pole is in perpetual shadow, so there are places where the crater walls shields the interior of the crater from the heat of the sun. Might even find water ice there.

Living on Mercury

• No atmosphere ((Very thin, to the point of being negligible)
• Extremes of temperature
• Heavy radiation from Sun
• Low gravity (0.38 g)
• High in metal content (but crust may be metal poor)
• Has magnetic field
• Long days (176 Earth days)
• 88-day year (Yes, it’s day is longer than its year)
• No orbital inclination. Poles are good real estate.

Venus

Has a phase just like the moon.

It doesn’t have continents the way Earth did. They don’t move around the way ours do. They are volcanic and impact deposits.

Living on Venus

• Same size as Earth.
• Pretty darned hot (880 F – lead melts at 620)
• Crushing atmosphere
  • 90 times Earth pressure
  • 1/10 the density of water (The equivalent of about half a mile deep in water on Earth)
• Mostly CO2, sulfuric acid in the clouds
• Gravity – .9 g
• Rotates retrograde (period – 243 days, but day length is 117 due to motion around Sun.
• 225 day year
• Could maybe live in cloud tops

Earth

If you have someone orbiting a planet, don’t lose track of the atmosphere. You’d see a visible stripe of the atmosphere and stuff rising through the atmosphere.

• Goldilocks zone
• Only place in Solar system where we can venture out unprotected
• Atmosphere protects from radiation and minor impacts
• Major impacts happen ~100 million years
• Will slowly grow warmer as Sun expands
• Deep gravity well – hard to get off.

The Moon

The moon is about as dark as asphalt.

• No atmosphere
• Radiation danger
• Basketball size rock hits the moon about once a week. If that hit a colony, they’d be toast.
• People would probably live underground
• 28-day day
• South Pole basin probably best real estate. (has water ice, perpetual shade and sunshine)

Mars

Mons Olympus largest volcano in the solar system but its a shield volcano so broad and with a gentle slope.

The moons would just look like specs. The moons orbit retrograde.

• Cold -220 to 70F
• Dust (not sand) storms
• Low gravity (0.38g, about twice Moon’s) Airplanes will work on Mars – need big wings.
• Nearly normal day (24.6 hours)
• Long year (1.9 Earth years)
• Medium-high meteor danger
• Phobos will eventually crash, because it has the retrograde motion.

The asteroid belt

They are really far apart. You’d never have someone dodging through an asteroid belt.

Vesta and Ceres are the two largest asteroids. Vesta’s image shows that it used to be totally round, but something smacked it and took a big chunk off the side. We have pieces of it on Earth. They did spectroscopic analysis to see that.

Ceres has enough water on it that if you got it close to the Sun you could terraform it and it would have seas and continents

Jupiter and Galilean moons

Jupiter looks like a target from the poles. (Aside from the terminator making half the planet dark)

Io is pulled on by Jupiter and the other moons so it’s constantly flexing, which heats up the surface.

Europa is miles thick of ice.

Ganymede also ice.

Callisto is peppered with craters

• No surface to Jupiter
• Gravity at cloud tops 2.4g
• Heavy radiation belts through the system.
• Moons are better real estate
  • Io maybe not so much (volcanoes!)
  • Outer three Galileans have lots of water
  • Dozens of others (63 discovered so far)
• Sunlight only 3.7% as bright as on Earth
• 10 hour day
• 12-year year.

Saturn

From Earth’s perspective Saturn has quite the tilt to it, so we see the the rings at very different orientation.

The rings are only a kilometer thick or so, even so, they cast a steep shadow on the planet. [Is it possible to have a ring around an earth like planet?] The rings are made of particles blown off the moons. Most of the debris comes from Enceladus.

The moons’ gravity sculpts the rings.

Saturn’s moons are as varied as the rings.

Hyperion! Go look at the photos!

Phobos

Telesto

Dione

Rhea

Iapetus – Has an equitorial wall, 8 – 12 miles high.

Titan – Possibility of life based on liquid ammonia or methane.

Looking at Saturn from the pole, it has a hexagon at the pole.

Living in the Saturn System

• No surface to Saturn
• Gravity at clouds top 0.9 g
• Rings are very thin
• Sunlight only 1% as bright as on Earth (About like a 1st quarter moon, so you’d need light amplification)
• 10 hour day (nearly same as Jupiter)
• 29-day year
• 60-63 moons discovered so far
• Titan is biggest by far with thick atmosphere
• Others are icy, heavily cratered

Uranus

• No surface
• Axi tilted to 98 ecliptic
• Really cold (-364F on cloud tops)
• Sunlight only .3% as bright as on Earth
• 18 hour day
• 84-year orbit
• 27 moons discovered so far

Neptune

• No surface to Neptune
• Very cold
• Sunlight only .1% as bright as on Earth
• 19-hour day
• 164-year
• 13 moons discovered so far
• Triton is best bet
  • Liquid-nitrogen-based life already there? Not a very good chance, but it could be.

Pluto – Charon

Basically a double planet with moons.

Not a planet anymore (Was “Dwarf planet” now “Plutoid”

Smaller than Earth’s moonlights

Cold as a politician’s heart (-360 to -400 F only 60 – 100 F above absolute zero

Atmosphere of nitrogen, carbon monoxide, and methane freezes out for most of its orbit

Sunlight only 0.0%- 0.1% as bright as Earth.

Comets

Basically just icy dirt balls floating around in space. They occasionally get gravitationally perturbed and they drop down into the inner solar system.

Deep Impact was sent into [name] comet

• Dark exterior
• Very loosely packed interior
• More a snowy dirtball than a dirty snowball
• Water ice
• Powdery dust (not sand or gravel)
• Carbon dioxide

Comets break apart naturally

• Highly irregular orbits
• Lots of volatiles
• May have organic compounds
• Minimal gravity
• Surfaces unstable when in inner system