AST 248 HW Problems for Chapter 1
Ryan Richards
Why are scientists interested in the possibility of life beyond Earth?
New discoveries in both planetary and biology disciplines have given hope that smaller life may
exist on other planets. There are also a plethora of planets and stars that have been recently
discovered and therefore have yet to been explored. Lastly, technology has vastly improved over
time which has given hope to finding new and innovative ways of searching for life beyond
Earth.
What do we mean by a geometric universe? In general terms, contrast a geometric view of
the universe with our modern view of the universe.
A geometric universe refers to a universe with the Earth at its center i.e. the Sun, Moon, stars and
other planets orbit around the Earth. As we now know, the Sun is the center of our universe
which is called a heliocentric universe. In fact, Kepler’s first law of planetary motion tells us the
Earth and the other planets orbit around the Sun in an elliptical orbit with the Sun at one focus.
What do we mean by a habitable world? Does a habitable world necessarily have life?
A habitable world is a world that contains necessities of life to form. Some of these include
energy, which is essential for sustaining life processes, water, atmosphere to shield life from
radiation and a sustainable temperature which after chemical reactions necessary for life. A
habitable world does not necessarily harbor life.
What do we mean by the “universality” of physics and chemistry? Although we don’t know
whether biology is similarly universal, what evidence makes it seem that it might be?
Universality means applicable to everything in our universe. As we know a famous example of a
universal law in physics is Newton’s law of universal gravitation. It says that the force between
two bodies under the influence of gravity is inversely proportional to the distance squared
between the centers of the bodies and proportional to their masses (In general this is valid if the
bodies move slowly compared to the speed of light or for weak gravitational fields; it’s a limiting
case of Einstein’s general relativity, a more complete description of gravity). This combined with
Newton’s three laws of motion can be used to explain Kepler’s planetary motion.
The evidence that makes biology a strong candidate for universality came from experimental
observations. Some of these include the organic molecules found in meteorites which are
essential for life, as well as in cloud gases between stars through spectroscopy.
Besides Earth, what worlds in our solar system seem most likely to have life? Why?
The candidates include Mars, Jupiter’s moons Europa, Castillo and Ganymede. Evidence has
shown that the surface of Mars once had flowing water. As discussed earlier, water is an
essential ingredient for a habitable zone. Europa is said to have a deep liquid flowing water
ocean beneath its icy surface. Less evidence has shown that Castillo and Ganymede has flowing
water as well on its surface. Also Titan, one of Saturn’s moons is a candidate said to have an
atmosphere and lakes of liquid methane as observed by Cassini. (Methane is an organic molecule
comprised of one carbon atom and four hydrogen atoms.
Could we actually detect life on an extrasolar planet and moon with current technology?
It may be possible but in my opinion highly unlikely. If there is life on these extrasolar planets
you can send signals throughout space such as radio waves and wait to see if you get a signal
back. However, you might have to wait an extremely long time before you get a return signal. Of
course this question seems more like speculation.
An extrasolar planet is (b) a planet that orbits a star other than our Sun
Today, the research known as SETI is conducted primarily by (a) scanning theskies for
signals from alien civilizations
Scientists today are interested in searching for life on Mars because (c) evidence suggests
that mars had liquid water on its surface in the distant past.