Astronomy Lecture Review

Flashcards based on lecture notes about astronomy, covering topics from planetary properties to stellar characteristics.

What two properties of a planet must be known to determine its average density?

Mass and volume

How does the average density of the inner versus outer planets in our system differ, and how does this affect their properties?

Inner planets have higher average densities than outer planets, affecting their size, gravity, and atmospheric density.

Which giant planet formed first?

Jupiter

What is significant about the snow line in the formation of the early solar system?

It marked the boundary beyond which icy bodies like comets and dwarf planets could form.

A Jeans instability is responsible for what event in the life of the solar system?

Gravitational collapse of a gas cloud

What is the prevailing theory for why Earth has such a large moon?

Giant Impact Hypothesis, where a Mars-sized protoplanet collided with the early Earth, ejecting debris that formed the Moon.

What are the different layers of the Sun’s atmosphere?

The photosphere, the chromosphere, and the corona.

Which layer of the Sun's atmosphere do we see?

Photosphere

What are some of the distinguishing features of the different layers of the Sun's atmosphere?

Temperature, density, and appearance

Describe briefly the proton-proton chain and its products.

A series of nuclear fusion reactions that converts hydrogen into helium, primarily in the cores of stars like the Sun.

Why is the solar cycle said to have a period of 22 years, even though the sunspot cycle is only 11 years long?

It encompasses the complete reversal of the Sun's magnetic field.

How do astronomers know that sunspots are areas of high magnetic fields (what physical effect do they measure)?

Zeeman effect, measuring the splitting of spectral lines in the light from the sunspot.

What two forces are responsible for stabilizing the Sun in hydrostatic equilibrium?

Gravity pulling inward and pressure pushing outward.

Why does thermonuclear fusion only take place in the Sun’s core?

It's the only location with the extremely high temperatures and pressures required for the process to take place.

What is a neutrino, and why are astronomers so interested in detecting neutrinos from the Sun?

Subatomic particles with almost no mass and no electric charge that provide information about the Sun's interior.

Why are we interested in Solar Weather? What negative effects can the Sun’s activity have here on Earth?

It can have significant impacts on our increasingly technology-dependent civilization and can damage satellites.

Describe the difference between apparent and absolute magnitudes of a star.

Apparent magnitude measures how bright a star appears from Earth, while absolute magnitude measures a star's intrinsic brightness.

How does the Brightness of a star change with the distance of the star from Earth?

A star's brightness decreases as distance from Earth increases.

What does a star’s Luminosity measure?

The total amount of energy it emits per unit of time.

What is the difference between the Luminosity and the Energy Flux of a Star?

Luminosity is an intrinsic property while Flux is the energy received at a specific location and is distance dependent

Does the star Betelgeuse, whose apparent magnitude is m = +0.5, look brighter or dimmer to us than the star Pollux, whose apparent magnitude is m = +1.1?

Betelgeuse will appear brighter than Pollux.

How and why is the spectrum of a star related to its surface temperature?

The hotter a star, the more energy it emits, and the shorter the wavelengths of that light tend to be.

What two measurements are used to classify stars on an H-R diagram? (Two correct answers are possible)

Absolute magnitude and/or luminosity and surface temperature.

How can astronomers use a stars luminosity class and H-R diagrams to calculate the distance to stars which are too far to directly measure by stellar parallax?

Analyzing the star's spectrum to determine its spectral type and luminosity class, then using the H-R diagram to estimate its absolute luminosity.

What physical phenomenon do astronomers use to measure the rotation of stars and the orbits of binary systems about their center of mass?

Doppler effect