Untitled Flashcards Set

What is Alpha Centauri?

Our nearest neighbors and a triple star system.

What method do we use to measure distances to nearby stars?

Parallax.

How far is the closest star, Proxima Centauri, from Earth?

4.24 light years.

How long would it take the fastest spacecraft to reach Alpha Centauri?

It would take a millennium.

What is the approximate distance to Alpha Centauri now?

165-155 AU.

How far is Proxima Centauri in AU?

252,964 AU.

How long would it take to reach Proxima Centauri?

74,000 years.

What stars make up the Centauri system?

Proxima Centauri and the binary stars Alpha Centauri A and B.

What is the solar neighborhood?

The collection of stars within 15 light years of the Sun.

How common are main sequence stars in the solar neighborhood?

Only about 4 stars per 1000 cubic meters, most are faint red dwarfs.

What is the Milky Way?

A diffuse band of light across the sky, containing nearly 200 billion stars.

What does Kepler's three laws address?

Planetary motion and orbits.

What is the formula for Kepler's 3rd Law?

P^2 = d^3.

What is parallax?

The apparent change in location of an object due to the difference in location of the observer.

What is the maximum distance measurable by the parallax method?

100 parsecs with a parallax angle of 0.01 arc seconds.

What denotes distance in parsecs?

1 parsec is the distance at which a star has a parallax of 1 arc second.

How far is 1 parsec in light years?

3.26 light years.

What generates electromagnetic waves?

Accelerating charged particles emit electromagnetic radiation.

What happens to brightness with increasing distance?

Brightness decreases according to the Inverse Square Law.

How does the intensity of radiation change with distance?

Doubling the distance makes it appear four times as dim.

What is a characteristic of electromagnetic radiation?

It travels at the speed of light.

What is the relationship between frequency and energy in electromagnetic radiation?

Higher frequency means higher energy.

What types of light have more energy than visible light?

Ultraviolet, X-rays, and Gamma rays.

What does the eccentricity of an orbit define?

The amount of elongation in a planet’s orbit.

What did Tycho Brahe's work contribute to astronomy?

He provided data that helped Kepler formulate his laws of planetary motion.

What is perihelion?

The point in a planet’s orbit closest to the Sun.

What is aphelion?

The point in a planet’s orbit farthest from the Sun.

What are the two long range forces?

Electromagnetism and Gravity.

What is the importance of parallax in distance measurement?

It measures the angle change to determine how far away an object is.

What is the relationship between speed and distance in Kepler's second law?

A planet moves faster when closer to the Sun.

What is the effect of increasing the distance of a light source on its apparent brightness?

It falls off with the square of the distance.

What type of stars are most common in the Milky Way?

M-type red dwarfs.

How many stars are there approximately in the Milky Way?

Nearly 200 billion.

What happens to the orbital period of a planet as its distance from the Sun increases?

The orbital period increases.

What are the units used for measuring distances in astronomy?

Parsecs and light years.

What is the purpose of electromagnetic radiation in observing space?

It allows us to study distant objects in the universe.

According to Kepler's first law, what shape do planetary orbits take?

Ellipses.

What represents the speed in the electromagnetic wave equation?

The speed of light.

What does an increase in the frequency of an electromagnetic wave imply?

Higher energy.

What can a larger parallax angle signify about a star?

It is closer to Earth.

What do we call the type of radiation that includes visible light?

Electromagnetic radiation.

What tools do astronomers use to measure stellar distances?

Parallax and brightness measurements.

What does electromagnetic radiation consist of?

Waves with electric and magnetic components.

What characterizes the light sensitivity of human eyes?

They are most sensitive to yellow light.

What is a major limitation of the parallax method?

Parallax shifts become unmeasurable at great distances.

What does the orbital eccentricity of 0 indicate?

A perfect circle.