Universe - Unit 1 Topic 1 Note Taking Guide

Vocabulary-style flashcards covering key concepts from Earth's history, the geologic time scale, habitable conditions, and major events such as the Moon-forming impact and Jupiter's protective role.

Geologic Time Scale

Timeline/history of Earth with key events.

Age of the Earth

Approximately 4.6 billion years.

Eons, Eras, and Periods

Geologic time divisions: eons are the largest units, followed by eras and then periods.

Major Global Events

Significant events in Earth's history, including both geological and biological milestones.

Geological vs Biological Event Spacing

Geological events tend to occur over longer, spread-out intervals; biological events cluster closer to today.

Goldilocks Principle

Conditions that are 'just right' for life; Earth located in a habitable zone with suitable water and temperature.

Habitable Zone

The region around a star where conditions permit liquid water and life.

Moon Formation

A Mars-sized body collided with Earth, ejecting debris that coalesced into the Moon.

Moon and Tides

The Moon's gravity creates tides on Earth.

Jupiter's Shield

Jupiter's gravity helped protect Earth by deflecting or absorbing many asteroids/comets.

Lucky Breaks for Earth

Favorable circumstances (habitable zone, water presence, timing of impacts, and planetary dynamics) that allowed life to develop.

planetary systems

Collection of small or large bodies that orbit a central star or multiple stars

stars

celestial body made of gas, hydrogen, and helium that admit, light and heat

galaxies

large group of gas, dust, and stars held together by gravity

spiral

arms that form a spiral, our galaxy the Milky Way. It looks like an octopus.

elliptical

resembles a rugby ball with a bright center in the middle

irregular galaxy

no clear shape and varies in size

cluster

concentrating group of galaxies

voids

spherical areas with little matter exist between galaxies