Universe 101: Cosmic Scales, Astronomy, and Origins

What is Earth's cosmic address?

Earth, Solar System, Milky Way Galaxy, Local Group, Virgo Supercluster, Laniakea Supercluster

What is the Sun classified as?

An ordinary middle-aged star

List the planets in our solar system in order from the Sun.

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

What are the three types of smaller bodies in our solar system?

Dwarf planets, asteroids, comets

What is a light-year?

The distance light travels in one year, approximately 9.5 trillion kilometers or 6 trillion miles

How long does it take light to travel from the Sun to Earth?

8.13 minutes

What is the observable universe estimated to contain?

Roughly 2 trillion galaxies

What percentage of the universe is made up of dark matter and dark energy?

95%

What is the cosmological principle?

Matter and energy behave throughout space and time as they do today on Earth; there are no special locations or directions in the universe.

What is Occam's Razor?

Choose the hypothesis requiring the fewest assumptions when multiple hypotheses explain observations equally well.

What is the first step in the scientific inquiry process?

Observation

What is a hypothesis?

An idea that leads to testable predictions.

What is a theory in scientific terms?

A well-developed idea that agrees with known physical laws, makes testable predictions, and has survived repeated testing.

What is the significance of black holes in modern astronomy?

They were first hypothesized in the late 1700s and observed in the 1970s-1980s, demonstrating the effects of gravity on light.

What role does mathematics play in astronomy?

It enables accurate predictions about natural systems, helps in pattern recognition, and allows for compact communication of complex material.

What is the process of stellar recycling?

End-of-life stars eject material into interstellar space, mixing with material from other stars, leading to the formation of new stars and planets.

What is the origin of heavy elements in the universe?

Heavy elements are formed in the cores of stars through nuclear fusion and are spread throughout the universe when stars explode.

What is the current status of evidence for extraterrestrial life?

There is no scientific evidence indicating life exists on any other planet.

What is the challenge of exobiology?

It relies on Earth-based knowledge to speculate about life elsewhere, but much remains theoretical.

What is the significance of the cosmic timeline?

It compresses the entire history of the universe into a 24-hour day, illustrating the vastness of cosmic time.

What event marks the beginning of the universe?

The Big Bang

At what time did the first stars and galaxies appear in the cosmic timeline?

Within the first 10 minutes after the Big Bang.

When did modern humans appear in the cosmic timeline?

At 11:59:59.8 PM on the cosmic clock.

What are the key requirements for scientific tests?

Tests must be reproducible, repeatable, and falsifiable.

What is the significance of the first exoplanets discovered?

They were giant Jupiter-like planets orbiting very close to their stars, challenging existing theories of planetary formation.

What is the main question regarding the origins of heavy elements?

Where did Earth's iron core and our body's carbon come from?

What does the term 'stardust' refer to?

The idea that all matter around us consists of atoms forged in the interiors of stars.