How Much Do You Know?

Test Your Might – How Much Do You Know?

If your mass is 60 kg on Earth, what would your mass be on the Moon?

Answer: 60 kg

Mass is the amount of matter in your body (The Essential Cosmic Perspective 84-85).  A person’s mass does not change.  Weight refers to a force that is acting on your mass.  If I stood on the Moon, I would weigh less, but my mass would be the same.


What causes the apparent retrograde motion of the planets?

Answer: As Earth passes another planet, the other planet appears to move backwards in respect to the background stars, but the planet’s motion does not really change.

Earth’s orbit is smaller than the orbits of any planets that are farther from the Sun, like Mars for example.  As Earth passes Mars in its orbit, Mars appears to move backward (westward) relative to the stars .  Although Mars appears to be moving backward, it really is not.  It looks like it is moving backwards because Earth orbits the Sun faster than the planets further from the Sun.


A typical shooting star in a meteor shower is caused by a ­­­­­­­­_________ entering Earth’s atmosphere.

Answer: pea-size particle from a comet

Comets eject sand – to pebble – size particles that are too big to be affected by either the solar wind or sunlight.  These particles follow the comet in its orbit.  We see a meteor shower when particles from one or more of these particles enter Earth’s atmosphere and burn up.


On average, how often do impactors about 10 km in size, large enough to produce mass extinction, hit Earth?

Answer: once every hundred million years.

“…objects large enough to cause mass extinctions come tens of millions of years apart”.  The larger the size of the impactor, the longer the typical time between impacts will be.


What worlds have the thinnest lithospheres?

Answer: Earth and Venus

The lithosphere includes the crust and part of the mantle.  It is the outer layer of cool, rigid rock.  Venus and Earth have the thinnest lithospheres out of Mercury, Venus, Earth, Mars, and Earth’s moon.


The Copernican Revolution started with…

Answer: the model of Copernicus, used the observations of Tycho, the mathematics of Kepler, and ended with the logic and observations of Galileo.

Copernicus created the heliocentric model of the galaxy.  Tycho’s observations provided more accurate data.  Kepler provided the idea that planets travel in ellipses.  Finally, Galileo created experiments and made telescopic observations that overcame any remaining scientific objections to the Copernican idea.


Under what circumstances can differentiation occur in a planet?

Answer: The planet must have a rocky surface.

Differentiation is the process by which gravity separates materials by density.  Differentiation occurs in planets that are hot enough in their cores for the rock and metal to melt and separate.  These planets are terrestrial planets (inside the frost line).


What is not a product of outgassing?

Answer: Oxygen

The most common gases released by outgassing are water vapor (H20), carbon dioxide (CO2), and Nitrogen (N2).  Oxygen is not a product of outgassing.


What are the two main differences between extrasolar planetary systems discovered to date and our Solar System?

Answer: extrasolar planet orbits tend to be closer and more eccentric than in our solar system

Many extrasolar planets orbit quite closely to their stars or have highly elliptical orbits.


The nebular theory of the formation of the solar system successfully predicts all but one of the following. What does the theory not predict?

Answer: the equal number of terrestrial and jovian planets

The Nebular theory describes how our solar system formed from an interstellar gas cloud, but it does not explain why there are an equal number of terrestrial and jovian planets.


What is the origin of almost all the large moons around the jovian planets?

Answer: they were formed by condensation and accretion in a disk of gas around the planet.

The large moons are almost circular and lie close to the equatorial plane of their parent planets.  Also, the large moons orbit in the same direction as their parent planets.  These facts suggest that the moons were formed by accretion within the disks of gas surrounding individual jovian planets.


What is true of the celestial equator and at all latitudes?

Answer:  It represents an extension of the Earth’s equator onto the celestial sphere

The celestial equator is defined as a projection of Earth’s equator into space, which makes a complete circle around the celestial sphere.


What conditions are required for a solar eclipse?

Answer: The phase of the Moon must be new, and the Moon’s orbit must be nearly aligned with Earth and the Sun

The definition of a solar eclipse says that it occurs when the Moon’s shadow falls on the Earth, which only occurs at new moon.  Also, the solar eclipse occurs when the Moon lies directly between the Sun and the Earth.  This means that the Moon’s orbit needs to be almost nearly aligned with the orbit of Earth, and the Sun.


According to our theory of solar system formation, why do we find some exceptions to the general rules and patterns of the planets?

Answer: Most of the exceptions are the result of giant impacts or close gravitational encounters

The formation of the solar systems suggests that all of the major features of the solar system can be explained, but there are some small exceptions.  Scientists believe that most of the exceptions arose from collisions or close gravitational encounters.


Which internal energy source produces heat by converting gravitational potential energy into thermal energy?

Answer: both accretion and differentiation

Accretion describes the process by which objects are pulled together by the force of gravity, heat up, and combine.  Differentiation describes the process by which gravity separates materials by density.  This only occurs in planets that have cores that can melt.  Dense metals sink toward the center while less dense, rocky material moves toward the surface.


If during this test, the universal law of gravitation, suddenly became Fg = GmM/d4 then…

Answer: the planets would escape from the Solar System


What are greenhouse gases?

Answer: gases that absorb infrared light

The definition for greenhouse gases is: “gases, such as carbon dioxide, water vapor, and methane, that are particularly good at absorbing infrared light but are transparent to visible light.


Why does Mars have more extreme seasons than Earth?

Answer: because it has a more eccentric orbit

Mars eccentric orbit causes it to be closer to the Sun in certain areas than the Earth is.  This causes more extreme seasons (hotter summers and colder winters).


Why won’t Pluto collide with Neptune?

Answer: the two planets have an orbital resonance that prevents them from colliding

Pluto’s orbit is more elliptical and more inclined to the ecliptic plane than that of the first eight planets.  There is no danger of a collision because Neptune orbits the sun 3 times for every two Pluto orbits; this stable orbital resonance means that Neptune is always a safe distance away when Pluto approaches.


Which of the following worlds has the most substantial atmosphere?

Answer: Venus

Venus has a far thicker atmosphere than Earth.  On Earth, most of the carbon dioxide is locked up in carbonate rocks, but on Venus, carbon dioxide is mostly gaseous (96%).  Also, the surface pressure of Venus is 90 times that of Earth.


How did you do?  If you somehow managed to get all of these right, or even close, we applaud you.  Quit your job immediately because you should be teaching this.


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