Chapter 1 : Astronomy 10

What is astronomy?

(class definition) study of: comets, moon phases, planets, stars, galaxies, nebulae, time (start and end), telescopes, and life; study of everything

(textbook definition) Precision measurement of the position and motion of astronomical objects.

parts of the universe

Galaxies, nebula, stars, planets, dwarf planets, moons, asteroids, comets

technology used

telescopes, satellites, probes, rockets

people used

scientists, explorers, military, business people

How people and technology are connected

directly- building crafts, Landing on the moon, etc.

indirectly- observe with our eyes and understand with our brain, using telescopes to data collect

the scales of the universe

mass, size, time

Milky Way

The galaxy in which our Sun and Solar System reside

local group

The small group of galaxies of which the Milky Way and the Andromeda galaxies are members.

local supercluster

A very large, gravitationally bound collection of galaxy clusters and galaxy groups containing tens of thousands to hundreds of thousands of galaxies

universe

All of space and everything contained therein.

Planet

A large body that orbits the Sun or another star and shines only by light reflected from the Sun or star. 2. In the Solar System, a body that orbits the Sun, has sufficient mass for self-gravity to overcome rigid-body forces so that it assumes a spherical shape, and has cleared smaller bodies from the neighborhood around its orbit.

comet

A complex object consisting of a small, solid, icy nucleus; an atmospheric halo; and a tail of gas and dust.

asteroid

Also called *minor planet*. A primitive rocky or metallic body (planetesimal) that has survived planetary accretion. Asteroids are the parent bodies of meteoroids.

dwarf planet

A body with characteristics similar to those of a classical planet except that it has not cleared smaller bodies from the neighboring regions around its orbit

Planetary system (solar system)

A system of planets and other smaller objects in orbit around a star.

Star

A luminous ball of gas that is held together by gravity and normally powered by nuclear reactions in its interior.

Grand Unified Theory (GUT)

A unified quantum theory that combines the strong nuclear, weak nuclear, and electromagnetic forces but does not include gravity.

primordial light atoms

hydrogen, helium, Deuterium , lithium, beryllium (H, He, D, Li, Be)

matter

1. Objects made of particles that have mass, such as protons, neutrons, and electrons. 2. Anything that occupies space and has mass.

anti-matter

Matter made from antiparticles.

Big Bang

the event that occurred 13.8 billion years ago that marks the beginning of time and the universe.

Cosmological principle

The (testable) assumption that the same physical laws that apply here and now also apply everywhere and at all times, and that there are no special locations or directions in the universe.

Universe’s structure sequence

forces; elementary particles; protons & atoms; galaxies; stars; us

We are made from stars

stars were made from light elements (I.e. hydrogen) and other large elements (silicon and carbon). When first stars died, materials were released back into universe and the atoms were the building blocks for “everything”

Earth’s general motion in the Universe

rotation= orbital (around the Sun) → the Sun travels in the Milky Way→ the Milky Way headed to Andromeda →the Universe expanding

cosmic address

our planet, star, galaxy, galaxy group, galaxy cluster, and galaxy supercluster

order of our cosmic address

Earth (rotates on its axis; orbits around the Sun) →Solar System → Solar Interstellar Neighborhood →Milky Way →Local Group →Cluster → Supercluster→ Filaments connect the supercluster→Universe

Scientific Method

1. Observe 2. Hypothesize 3. Predict → Test 4. Observe result 5. If ok then test again OR If not ok re-hypothesize (aka start over)

Drake’s Equation

purpose: estimate number of communicating civilizations in our galaxy right now; aliens?