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Geology 109 > Background Information > Flashcards

Background Information Flashcards

1
Q

What did humans believe 3,000 years ago?

A

Stars were fixed relative to other stars, and moved predictably across the sky. They saw retrograde motion separating planets and stars - however, they did not think of Earth as a planet. The movement in the sky (hevens) were attributed to deities. The Universe was geocentric, and this was “Proven” by Ptolemy (100-170 CE) and was believed to be true for 1,400 years.

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2
Q

Who “proved” the geocentric idea of the universe?

A

Ptolemy (100-170 CE).

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3
Q

What happened during the Renaissance/15th Century?

A

A rebirth of rational thinking (Copernicus, Kepler, Galileo). Earth didn’t centre the universe, planetary orbits weren’t circular, not all bodies orbited earth.

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4
Q

What did Copernicus accomplish?

A

Published evidence for heliocentricity (orbiting the sun).

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5
Q

What did Kepler accomplish?

A

Elliptical planetary orbits refuted Ptolemy.

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6
Q

What did Galileo accomplish?

A

Observed moons orbiting Jupiter (impossible for geocentric to be right).

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7
Q

What did Sir Isaac Newton devise during the Enlightenment?

A

(1642-1727) Devised the Law of Universal Gravitation, the Three Laws of Motion, the mathematics of change (calculus). He proved that natural law governs natural events, and the idea of Geocentricity faded away.

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8
Q

What is the Doppler Effect?

A

The most intuitive way to help us understand what is going on with the universe as a whole. Waves compress or relax with relative motion; this applies to both sound and light waves.

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9
Q

How does the Doppler Effect effect stars?

A

A moving star displays Doppler-shifted light. Light from an approaching star is compressed, this causes a shift to higher frequencies, so that stars moving toward Earth are shifted towards blue. Light from a receding star is expanded, causes a shift to lower frequencies, so that stars moving away from Earth are shifted toward red.

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10
Q

What do light from distant galaxies appear as?

A

“Red shifted”

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11
Q

What did Hubble recognize in 1929?

A

That the red shifted light from distant galaxies was a Doppler shift, and concluded that galaxies were moving away rapidly. No galaxies were found to be moving toward Earth. This led to the development of the Expanding Universe Theory, analogous to expanding bread or blowing up a balloon.

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12
Q

When did the Universe begin to expand?

A

With the Big Bang, all of the mass and energy in the Universe was paced into a single small point. It exploded 13.7 BYA and has been expanding ever since.

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13
Q

What is the Big Bang rooted in?

A

The Laws of Physics.

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14
Q

What did the Big Bang start as?

A

A rapid cascade of events; protons and neutrons formed within 1 second, hydrogen atoms formed within 3 minutes, hydrogen fused to form new light elements (He, Be, Li, B) via big bang nucleosynthesis.

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15
Q

What happened as the Universe continued to expand?

A

It cooled and decreased in density.

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16
Q

What four facts need to be explained for where the solar system came from?

A

1) The orderly motion of everything
2) The two basic types of planets
3) Asteroids and comets
4) Exceptions to the rules

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17
Q

Describe: The Orderly Motion of Everything

A

All planets, all asteroids, and most moons orbit in the same direction.
Most planets and moons rotate in the same direction, the direction in which they orbit.

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18
Q

What are the two basic types of planets?

A

Terrestrial Planets (Earth Like) and Jovian Planets (Jupiter Like)

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19
Q

What is a Terrestrial Planet?

A

Made of rocks and metals, not very big, closet to the Sun (first four).

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20
Q

What is a Jovian Planet?

A

Made of gases, very big, furthest from the Sun (last four).

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21
Q

What are Asteroids?

A

Made of rocks and metals, very small, mostly between Mars and Jupiter. Found in orbit around the sun in the “asteroid belt”

22
Q

What are Comets?

A

Made of ices, very small, mostly beyond Neptune.

23
Q

What are Trojan asteroids?

A

Asteroids in the orbit of Jupiter.

24
Q

What are the Exceptions to the Rules for where the solar system came from?

A

1) One planet rotates backwards (Venus)
2) One planet rotates sideways (Uranus)
3) Several moons orbit backwards
4) Our moon is too big (significantly)
5) Pluto has a funny orbit and is neither terrestrial nor jovian.

25
Q

What is the Oort Cloud?

A

A composition of many billions of comets.

26
Q

What elements did the Big Bang create?

A

Only hydrogen (70%) and helium (30%), and small amounts of other light elements.

27
Q

What were the very first stars (first generation stars) composed of?

A

Only hydrogen and helium.

28
Q

What did the first stars create?

A

The first heavier elements.

29
Q

When have generations of stars other than the first been composed of?

A

Hydrogen, helium, and other heavier elements.

30
Q

What is the Nebular Theory?

A

The theory for where the solar system came from; the solar nebula is the cloud that formed our Sun. A cloud of dust/debris that is floating around in the galaxy.

31
Q

What is the composition of the solar nebula?

A

70% Hydrogen, 28% of Helium, 2% of heavier materials (Hydrogen compounds; methane, ammonia, water [1.4%], rocky material [0.4%], metallic material [0.2%]).

32
Q

When does a star form? (Nebula Theory)

A

When a cloud of gas collapses under gravity. Rotation causes some of the cloud to “spin out” into a disk around the sphere. The result is a dense sphere in the centre (the sun) and a disk of leftover debris (planets, moons, asteroids, comets).

33
Q

What does the Debris of the Nebula Theory include?

A

Very light elements (mostly Hydrogen and Helium), heavy elements (silicates [common rock forming minerals], iron, nickel), and “In Betweens” (Hydrogen compounds; ammonia, water, methane).

34
Q

Do objects tend to stick together or pull apart?

A

Objects tend to stick together, given the chance. This happens because of the electromagnetic force (small things) and gravity (big things). Things resist sticking together because of the energy force they have (little energy sticks together easily, lots of energy doesn’t stick together well).

35
Q

What are the conditions of the inner solar system?

A

Near the Sun is hot; particles don’t stick together well. Only heavy things stick (rocks and metals), lighter particles were “blown” away by the Sun’s energy.

36
Q

How were inner solar system planets made?

A

Rocks and metals began to clump together; when clumps grew large enough, they began to stick together by gravity (planetesimals). Planetesimals grew rapidly.

37
Q

What planets formed in the inner solar system?

A

5 or 6 small rocky (terrestrial) planets eventually formed, four remain today (Mercury, Venus, Earth, Mars).

38
Q

What happened to the remaining rocky/metallic debris in the inner solar system that didn’t form planets?

A

The remaining debris formed the asteroids; perhaps 100,000 exist today, primarily in the asteroid belt (between the orbits of Mars and Jupiter).

39
Q

What is beyond the frost line?

A

Cold; all kinds of particles stick together easily. Rocks and metals started sticking together. Hydrogen compounds stuck together to form ices; planetesimals formed from these solid chunks.

40
Q

What formed in the outer solar system?

A

Four large balls of rock, metal, and ice formed. The largest two gathered most of the Hydrogen and Helium gas that remained (Jupiter and Saturn). The other two gathered other gaseous material (formed Uranus and Neptune).

41
Q

What did the remaining icy debris form in the outer solar system?

A

The remaining debris formed moons and comets; more than 60 moons are now found orbiting the four jovian planets. More than one billion comets are believed to exist, mostly out beyond Neptune.

42
Q

How many moons does Mercury and Venus have?

A

None.

43
Q

How many moons does Mars have?

A

Two.

44
Q

What are Exceptions to the Nebular Theory?

A

The nebular theory predicts lots of rocks, ice, etc., tumbling around. Moons with “backward” orbits were captured from this debris. Should have been lots of impacts, especially early one. Planets with odd rotations could have been “knocked” by an impactor. Our moon may have been created by an impact.

45
Q

What is explained with the Nebular Theory and the Four Challenges?

A

Orderly motion - yes, since motion came from the original rotation of the solar nebula.
Terrestrial and jovian planets - yes, difference arises from temperature difference between inner and outer solar system.
Asteroids and Comets - yes, the temperature difference (Rocks closer to Sun, Ice farther from Sun). Exceptions - the leftover debris and impacts.

46
Q

Why was Pluto’s status debated?

A

There was a long debate over whether it was a very large comet, or a very small planet. In 2006, a new category was created called Dwarf Planets that includes Pluto plus a number of other small objects in the solar system (mostly in the area of the Kuiper Belt).

47
Q

Where are most of the Dwarf Planets located?

A

In the Kuiper Belt.

48
Q

Define Planet.

A

Defined in 2006, a planet:
Is a large solid body orbiting a star (Sun), has a nearly spherical shape, has cleared its neighbourhood of other objects.

49
Q

Define Moon.

A

A solid body locked in orbit around a planet.

50
Q

What is the order of the Planets?

A

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

51
Q

What is the order of the Dwarf Planets?

A

Ceres, Pluto, Haumea, Makemake, Eris.

52
Q

Why is Pluto Exceptional?

A

Pluto’s orbit changes (goes in an out of Neptune’s orbit). But unlike asteroids/comets, it is spherical and has objects orbiting it.

Geology 109 (17 decks)

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