AST - Search for Life in the Universe

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Astrobiology

The scientific study of life int he universe, including how life began, how it evolved, where it might exist, and whether life exists beyond earth

Extraterrestrial

Originating outside of Earth. Extraterrestrial life means life that originated somewhere other than Earth.

Why Earth Matters

Earth is our only confirmed example of life, so scientists use Earth life as a starting point when thinking about life elsewhere.

Liquid Water

All known life requires liquid water. However finding liquid water by itself doesn't prove that life exists.

Places scientists consider

Potential environments include Mats, Europa, Enceladus, and Titan. Scientists look for environments that would provide conditions suitable for life.

Evidence vs Speculation

Scientists distinguish what is known, what is possible, and what has actually been supported by evidence.

Interdisciplinary Science

Astrobiology draws on astronomy, planetary science, biology, chemistry, geology, and physics

Geocentric Model

Earth-Centered Model

Heliocentric Model

Sun-centered model of the Solar System

Copernican Principle

The general idea that Earth does not occupy a special or central position in the universe

Hypothesis

A proposed explanation that can be tested

Scientific Theory

A well-supported explanation that has survived extensive testing. A scientific theory is not a simple guess.

How science works

Scientists make observations, ask questions, develop hypotheses, make predictions, test them, analyze evidence, and revise explanations when needed.

Self-Correcting science

When new evidence conflicts with an existing explanation, scientists can modify or replace that explanation

Universe

Everything that exists, including space, time, matter, and energy

Galaxy

A huge collection of stars, gas, dust, and other materials held together by gravity

Cosmic hierarchy

Earth → Solar System → Milky Way Galaxy → Universe

Light-Year

A unit of distance equal to the distance light travels in one year. It is not a unit of time. Looking at distant objects also means looking into the past.

Big Bang Theory

The leading scientific explanation that the universe began in an extremely hot, dense, state and has been expanding.

Redshift

A shift. of light toward longer, redder wavelengths. The redshifts of distant galaxies are important evidence for an expanding universe.

Atoms

Atoms contain protons (positive), neutrons (no charge), and electrons (negative). Atomic number equals the number of protons.

Important elements for life

Hydrogen, Carbon, Nitrogen, and oxygen are especially important. Carbon can form many complex molecules.

Planets in order

Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune

Terrestrial Planets

Mercury, Venus, Earth, and Mars. They are rocky and relatively small.

Jovian planets

Jupiter, Saturn, Uranus, and Neptune. They are much larger and rich in gases and other volatiles.

Nebular Theory

A model for the solar system formation: a cloud of gas and dust collapsed under gravity, flattened into a rotating disk, and formed the Sun at the center and planets from material in the disk.