Cosmic Foundations of Life: Astronomy & Astrobiology Concepts

Posted on May 24, 2025 in Physics

The Science of Life in the Universe

The possibility of extraterrestrial life was first considered: many thousands of years ago during ancient times.
The methods of modern science were originated by the: Greeks.

Geocentric Model: A spherical Earth at the center of the universe, surrounded by a celestial sphere.
Heliocentric (Sun-centered) Model: Describes the relative motion between Earth and other planets in their orbits.
Stellar Parallax: The apparent shift in position of nearby stars as Earth moves around the Sun.

1st Law: The orbits of the planets are ellipses with the Sun at one focus.
2nd Law: An imaginary line joining the Sun and a planet sweeps out equal areas in equal times.
3rd Law: The further a planet is from the Sun, the slower it moves in its orbit.

In its elliptical orbit, a planet is closest to the Sun at: Perihelion.
In its elliptical orbit, a planet is furthest from the Sun at: Aphelion.
Einstein was able to explain what gravity is, while Newton was only able to explain how gravity works.

The universe is very large, suggesting that enormous numbers of habitable planets may exist.
The universe is very old, suggesting that there has been plenty of time for life to have appeared and evolved elsewhere.
The chemical elements that make up life on Earth are common, suggesting that extraterrestrial life may be constructed in a similar fashion to life on Earth.

Structures in our part of the universe in increasing scale (smallest to largest): Solar System, Milky Way Galaxy, Local Group, Local Supercluster.
The Milky Way galaxy contains approximately: a hundred billion stars.
Most of the mass of the Milky Way is in the form of: Dark Matter.
In our Milky Way galaxy, the Sun is located: in the disk.
The universe appears to be made of: Dark Energy.

The strongest piece of evidence supporting the Big Bang Theory is the: detection of the cosmic microwave background radiation left over from the formation of the universe.
The rate of expansion of the universe has been speeding up.
In the process of Nuclear Fusion: Two or more nuclei fuse or stick together to form a heavier nucleus whose combined mass is slightly less than the original nuclei.
A star that is more massive than the Sun will have: a shorter lifetime because its central core is hotter.
We are located at the: center of our observable universe.
Due to its massive size, the search for extraterrestrial life is largely limited to the Milky Way Galaxy.

Terrestrial Planets: Small, made mostly of rock and iron with high densities, and found close to the Sun.
Jovian Planets: Large, made mostly of gases and liquids with low densities, and found far from the Sun.

The most abundant materials in the solar nebula were: Hydrogen and Helium.
In the nebular theory, the process by which planets form is referred to as: Accretion.

Isotopes have the same number of: protons but a different number of neutrons.
If Photon A has a higher energy than Photon B, then: Photon A has a higher frequency than Photon B.
Electromagnetic spectrum in increasing wavelength: X-ray, Visible, Infrared, Radio.
Electromagnetic spectrum in increasing frequency: Radio, Infrared, UV, Gamma Ray.