Chapter 12 astronomy

The fact that the surface of Mars shows no tectonic activity means that one of the requirements for continuing life might be missing.

A carbon-return process.

If we should find micro-organisms on Mars that reproduce using a DNA/RNA scheme and set of amino acids that are mirror images of those used in all Earth life-forms, that would support the

Abiogenesis Model.

In current Earth life, the self-copying molecule that contains the information needed to construct and operate a life-form is

DNA.

Which of these moons has geysers of water shooting out through cracks in the moon, indicating a subsurface ocean?

Enceladus.

Which of these moons has patterns of cracks in the ice on its surface. indicating a subsurface ocean?

Europa.

A type M star that is known to have three terrestrial-size planets near or in its habitable zone is

Gliese 581.

Which of the following statements qualifies as a falsifiable working hypothesis of the sort that Karl Popper would favor?

Life arose on Earth and exists only there.

Which of the following statements best describes the presence of water on Mars?

Mars probably had liquid water flowing on its surface at some time in the past.

Which of the following systems is closest to the plan of most current Earth life-forms?

One DNA molecule is used to make RNA molecules which, in turn make the proteins and enzymes that construct and operate a life-form.

A single sugar phosphate chain with nitrogenous bases attached along it describes a molecule of

RNA

A technological civilization that lasts for astronomically significant periods of time should make an obvious and visible impact on the galaxy and should have figured out how to visit us by now. That leads to the question "So, where are they"? This statement and question is usually referred to as

The Fermi Paradox.

Suppose that you observe a planet that reflects mostly green light and absorbs both red and infra-red light. Which of the following conclusions can you make?

The planet does not have Earth-type green plants on its surface.

Which of these moons has landmarks that are not rotating with the rest of the moon, indicating a subsurface ocean?

Titan.

When a hydrogen atom on one molecule is attracted to an oppositely charged part of another molecule, the result is

a hydrogen bond.

When the light from a star is spread out into a rainbow of colors, the resulting picture is called

a spectrum.

Here is the Drake Equation. In this equation, N stands for the

average number of new stars that form in a year.

The Viking Landers carried out several experiments on Martian surface soil in order to detect the presence of life. Those same experiments were also carried out on a control sample of Martian surface soil that had been sterilized by heat. The purpose of doing experiments on the control sample was to

avoid getting a false positive result.

A necessary (but probably not sufficient) condition for a planet to have active plate tectonics is that it

be considerably larger than the planet Mars.

The oxygen atom in a water molecule

carries a negative electrical charge

The strongest evidence that Earth life is all descended from a single self-copying molecule is that all Earth life

contains the same version of molecules that have different mirror-image forms.

Current computer models of planet formation suggest that the Alpha Centauri system

could have planets within the habitable zones of both Alpha Centauri A and Alpha Centauri B.

An advantage of carbon dioxide as the starting form of carbon for use by living things is that it

dissolves in liquid water.

The energy that is released when hydrogen combines with oxygen to form a kilogram of water is always

exactly equal to the energy needed to separate the hydrogen and oxygen in a kilogram of water.

The primary mission of the Kepler Spacecraft is to

find planets in orbit around nearby stars.

Which of the following types of radiation has the highest frequency on this list?

gamma rays.

If we detect that a star is sometimes moving toward us and sometimes moving away and also find that this pattern repeats at regular intervals, we know for sure that the star

has at least one object of unknown type orbiting around it

The molecules of both liquid water and ice are held together by

hydrogen bonds.

The early Earth probably had carbon

in the form of amino acids and other complex hydrocarbons

If the frequency of electromagnetic radiation goes from 9×10¹⁴Hz to 3×10¹⁴Hz, the energy of each individual photon in the radiation

is divided by 3.

The range of signal frequencies between absorption bands caused by hydrogen and hydroxyl molecules

is referred to as the "water hole" and is the frequency band that SETI programs usually choose.

A planet larger than Mars would be a good place to look for life because

it might retain enough interior heat to drive plate tectonics.

As compared to higher frequency electromagnetic radiation, lower frequency electromagnetic radiation will usually cause

less damage.

When ice melts, the resulting liquid water occupies

less volume than the ice did.

The reason that most SETI programs choose to listen at microwave radio frequencies is that

microwaves are the most energy efficient way to send information.

According to the definition of "habitable zone" that we are using, Earth is

near the inner edge of the habitable zone of our Solar System.

One of the experiments carried out by the Viking Landers was to use a mass spectrometer to analyze the gas given off from a heated soil sample. The results of that experiment (as interpreted at the time) established that Martian soil contains

no carbon compounds at all.

The original source of energy for life forms that live near a black smoker is

often chemicals generated by the heat of the Earth's interior.

Oxygen is

one of the four most common elements in the universe.

Silicon atoms can bond to other silicon atoms to form polysilylene molecules in much the same way that carbon atoms can bond to other carbon atoms to form sugars and other hydrocarbon molecules. What is the key difficulty with basing life on silicon and polysilylenes instead of on carbon compounds such as glucose?

polysilylenes tend to explode in the presence of oxygen

The difficult part of a SETI program is that you do not know what frequency band the extraterrestrials are using, so you need to listen to them all. The SERENDIP IV program, running on the Arecibo radio telescope, accomplishes this task by

sending a batch of signals to each of several million home computers for analysis.

The microfossils that were found in the martian meteorite ALH84001 are

subject to continued argument because of doubts that they are of biological origin.

Green plants obtain the energy they need from

sunlight

Compared to the frequency of photons absorbed during a transition from a from a -6ev state to a -4ev state, transitions from the -5ev state to a -3ev state would correspond to absorbing photons whose frequency is

the same.

If we detect that the intensity of the light from a star is mostly constant but drops slightly to a new constant value for a while and then returns to its normal level and repeats this behavior at regular intervals, we can reasonably suspect that

the star has a planet in orbit around it.

Our Sun's nearest neighbor star system is

two stars in close orbit around each other and a third star orbiting farther out.