Astronomy Week 4

What type of light does Earth's surface emit at night?

Infrared

Rank the following three forms of light given off by the Sun by their energy levels, from least energetic to most energetic: UV, Visible, and Infrared

Infrared, Visible, UV

Why does Venus have less impact craters than Mars

Because of its dense atmosphere, Venus is protected from smaller cratering impacts. Smaller chunks of material vaporize completely as they pass through its atmosphere.

Why is the shape of the magnetosphere not spherical like the shape of Earth?

Charged particles from the Sun moving at high velocities interact with the magnetic field, compressing it in the direction of the Sun and elongating the field away from the Sun.

The form of light that has the most difficult time passing through the atmosphere also has the ________

highest frequency B. lowest wavelength

Any rock produced by cooling from a molten state is

igneous

We believe that Venus started with a significant supply of water. Explain where that water is now.

liquid and either froze as temperatures dropped or evaporated water quickly became water vapor. This was lost into space when ultra-violet broke the water into H and O and lighter elements escaped from the top of the atmosphere.

What are Earth's core and mantle made of? Explain how we know

mantle is made of rock, which we know from chemical analysis of samples from upper mantle material that is ejected occasionally from volcanoes.

hat is the thickest interior layer of Earth? The thinnest?

mantle, crust

Any rock produced by physical and chemical alteration (without melting) under high temperature and pressure is

metamorphic

Any rock that has not experienced great heat or pressure and therefore remains representative of the original condensed materials from the solar nebula is

primitive

Any rock formed by the deposition and cementing of fine grains of material, such as pieces of igneous rocks or the shells of living things is

sedimentary

The fission hypothesis suggests

that the Moon was once part of Earth but separated early in their history

If all life suddenly disappeared from earth

the free oxygen in the atmosphere would quickly combine with surface rocks

What characteristics do the worlds in our solar system have in common that lead astronomers to believe that they all formed from the same "mother cloud" (solar nebula)?

their orbits lie in roughly the same plane B. They generally revolve and rotate in the same direction C. The chemical makeup of the giant planets is similar to the Sun. D. All of the above

In which atmospheric layer are almost all water-based clouds formed?

troposphere

Earth's surface is primarily heated by which two forms of energy?

visible and infrared

Which of the following is an effective greenhouse gas

water vapor

How does an atmosphere affect the surface of a planet and the ability of life to exist?

A dense atmosphere insulates the surface of a planet so that more heat is retained The composition of the atmosphere is also important: certain gases lead to a greenhouse effect, allowing the planet to be warmer than you would expect from its position around the Sun

What is the source of Earth's magnetic field?

As we know from the study of electromagnetism, it is electric charges in motion that generate a magnetic field. The rotation and internal circulation of Earth's iron and nickel core creates what is, in effect, an electric current.

How do asteroids and comets differ?

Asteroids are composed primarily of rock and metal while comets are typically icy objects Asteriods reside in the inner part of the solar system. Comets come from the outer solar system and become visible as they get closer to the Sun and the ice evaporates

Venus rotates backward and Uranus and Pluto spin about an axis tipped nearly on its side. Based on what you learned about the motion of small bodies in the solar system and the surfaces of the planets, what might be the cause of these strange rotations?

Collisions were frequent in the early solar system, so it is not unlikely that these strange rotations are due to collisions of these planets with significantly large objects during their formation or subsequent evolution.

What is comparative planetology and why is it useful to astronomers?

Comparative planetology is the study of how planets work and evolve by comparing them and the processes that have influenced their development.

How is Earth's Moon different from the larger moons of the giant planets?

Earth's moon resides relatively close to the Sun, so its composition is primarily rocky

Which of the following is part of the Earth's natural greenhouse effect?

Earth's surface and atmospheric gases absorb energy and then give off infrared light

Frozen water exists on the lunar surface primarily in which location? Why?

Frozen water exists primarily in deep craters on the Moon's south pole. Parts of these craters are permanently in shadow and therefore do not receive enough energy from the Sun to evaporate the ice and escape into space.

We were able to conclude that the Moon is dead geologically as a result of

Humans landing on the moon

Is it likely that life ever existed on Mars?

Mars is known to have had a wetter, warmer surface between 3 and 4 billion years ago. Thus, it is widely speculated that Mars may have developed an independent life at that time.

Using Appendix F, which planet(s) might you expect not to have significant seasonal activity? Why?

Mercury and Jupiter, because the inclination of their orbits is close to 0°. Venus might also be included because a 177° tilt is close to 180°, which is, effectively, zero.

What is the main consequence of Mercury's orbit being so highly eccentric?

Mercury's distance from the Sun varies hugely, ranging from 46 million km at perihelion to 70 million km at aphelion.

What is the relationship between Mercury's rotational period and orbital period?

Mercury's rotation is 59 Earth-days long, while the year is 88 Earth-days long. That is a ratio of 3 to 2. Thus, three Mercury days equals two Mercury years.

How was the Mars Odyssey spacecraft able to detect water on Mars without landing on it?

Odyssey used a gamma-ray spectrometer to detect hydrogen below the martian surface.

Why is there so much more carbon dioxide in the atmosphere of Venus than in that of Earth?

On Earth, much of the carbon dioxide originally in the atmosphere dissolved in the ocean water and is now found in sea sediments.

The priomordial atmosphere of the earth was primarily

Oxygen free and hydrogen rich

Why is a decrease in Earth's ozone harmful to life?

Ozone blocks solar ultraviolet radiation from reaching Earth's surface

What are the advantages of using radar imaging rather than ordinary cameras to study the topography of Venus?

Radar (radio waves) can penetrate Venus' planetary cloud cover, whereas visible light or infrared radiation can't.

Imagine you are a travel agent in the next century. An eccentric billionaire asks you to arrange a "Guinness Book of Solar System Records" kind of tour. Where would you direct him to find the following:

Saturn; B. Earth; C. Ganymede; D. Earth; E. Mercury; F. Venus; G. Jupiter; H. Venus; I. Titan; J. Io; K. Ganymede.

What is the composition of the Moon, and how does it compare to the composition of Earth?

The Moon is principally composed of silicate rocks, whereas Earth has more metals and volatile compounds. Earth has an iron core, but the Moon does not. Earth has liquid water in its surface layer, but the Moon does not.

Why does the Moon not have an atmosphere?

The Moon's mass, and therefore its gravitational force, is not large enough to retain gases and volatile compounds. Therefore, any gases released on the Moon quickly escape into space.

Why did the Sun form at the center of the solar nebula?

The Sun formed at the center due to gravitational forces, caused that material to stick together, and once the mass and density increased sufficiently, nuclear fusion caused a star to form: the Sun

What are some of the properties giant planets?

The giant planets also have many more moons compared to the terrestrial planets. The giant planets lie farther from the Sun and are large compared to the terrestrial planets.

What does a planet need in order to retain an atmosphere?

The gravity of a planet helps to determine whether an atmosphere can be retained.

What are the maria composed of?

The maria are composed chiefly of basalt.

Why are the lunar mountains smoothly rounded rather than having sharp, pointed peaks (as they were almost always depicted in science-fiction illustrations and films before the first lunar landings)?

The primary reason why the lunar mountains are smoothly rounded is that there has been no water/ice erosion on the Moon as there has been on Earth.

What was the solar nebula like?

The solar nebula was a huge cloud of material made up of gas and dust.

Which of the following is a primary characteristic of greenhouse gases?

They absorb some forms of light but allow other forms of light to pass through

Where would you look for some "original" planetesimals left over from the formation of our solar system?

They are found at a variety of distances from the Sun, so they can inform us about the entire structure of the solar system.

Earth's atmosphere is about 4/5 nitrogen and 1/5 oxygen;

True

Mercury can get very hot by human standards (roughly 700 K at noontime) and then become very cold at night (down to roughly 100 K), the largest variation in temperature for any planet.

True

With no wind or water erosion of rocks, what is the mechanism for the creation of the lunar "soil?" Billions of years of impacts breaking up the rocks and scattering the debris over the surface have created lunar "soil." Enough impacts have occurred to cover much of the surface with sand- and dust-sized particles.

True

Which type of light do the molecules in Earth's atmosphere absorb most effectively

UV

Why is UV light not an important energy source for heating Earth's surface?

UV light is almost entirely absorbed by Earth's atmosphere

Using Appendix F, which planets might you expect to have extreme seasons?

Uranus Pluto

Is it likely that life ever existed on Venus ?

Venus is too hot and dry for life, and there is no evidence that it once had a more comfortable climate.

Select the correct option(s)

Venus, Earth, and Mars are similar in that they consist of rock and metal for the most part, they are terrestrial planets, closer in to the Sun than the jovian planets, all have volcanic activity on their surfaces

Why is Mars red?

Winds on Mars are strong enough to blow surface dust all over the planet. This dust contain iron oxide, which gives it the rusty red color.

People get sunburns because

a small amount of ultraviolet light reaches the surface of Earth and burns skin

What is the composition of clouds on Mars?

dust clouds; water-ice, like those on Earth clouds of frozen carbon dioxide crystals (dry ice)