Astronomy Concepts: Stellar Distances and Motion

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Questions and Answers

What is the correct equation for calculating parallax distance?

d = p × 1

d = 1/p (correct)

d = p²

d = p + 1

What unit is used to measure the parallax angle?

Degrees

Arcseconds (correct)

Parsecs

Lightyears

Which of the following is NOT one of the three methods used to measure distances to space bodies?

Cepheid variables

Standard candles

Spectroscopy (correct)

Parallax

Which scientist challenged Aristotle's concepts of motion and provided evidence for heliocentrism?

Galileo Galilei Signup and view all the answers

What is the consequence of Newton's Law of Gravitation?

It is considered the first universal law. Signup and view all the answers

What is the limiting parallax angle that can be measured effectively from Earth?

0.01 arcseconds Signup and view all the answers

Which of the following statements is true regarding Newton's Laws of Motion?

They explain gravitational forces maintaining planetary orbits. Signup and view all the answers

What defines a force according to Newtonian physics?

A push or pull causing a change in motion. Signup and view all the answers

What does the 2nd postulate of special relativity state?

The laws of physics are the same for anyone moving at a constant velocity. Signup and view all the answers

What was one key outcome of the Michelson-Morley Experiment?

It demonstrated that light behavior is consistent regardless of direction. Signup and view all the answers

What is the significance of time dilation in the context of special relativity?

Time slows down for objects moving at speeds near light speed. Signup and view all the answers

In general relativity, what is described as the warpage or distortion of space-time?

Gravity. Signup and view all the answers

Which of the following wavelengths can penetrate the Earth's atmosphere?

Visible light. Signup and view all the answers

What does the term 'proper motion' refer to in astronomy?

The actual motion of stars across the sky as observed from Earth. Signup and view all the answers

Which of the following properties is NOT a major consideration for telescopes?

Signal-to-Noise Ratio (SNR). Signup and view all the answers

Which of the following is NOT an advantage of reflecting telescopes?

Reduced light absorption. Signup and view all the answers

Study Notes

Stellar Distances

Parallax is the apparent shift in a star's position against background objects, measured in arcseconds.
The parallax equation is:
d = 1/p, where p is in arcseconds and d is in parsecs.
The limiting parallax angle from Earth is 0.01 arcseconds.
The Gaia satellite observes parallax.
Proxima Centauri is the nearest star.

Proper Motion and Its Effect

Proper motion is the gradual shift of stars across the sky due to their actual movement.
Galileo used a telescope to observe the heavens and argued for the heliocentric model.
Galileo's evidence supporting the heliocentric model included:
Phases of Venus
Moons of Jupiter
Sunspots
Mountains/craters on the Moon

Newton’s 3 Laws of Motion

Newton's Laws of Motion explain the gravitational forces keeping planets in elliptical orbits around the Sun.
A force is a push or pull that causes a change in motion.
Newton's Law of Gravitation was the first universal law and is constant.

Closed and Open Orbits

Closed orbits can be circular or elliptical.
Open orbits can be parabolic or hyperbolic.

Einstein’s Special Theory of Relativity

The Special Theory of Relativity focuses on the effect of speed on time and distance.
Postulates:
No material object can travel faster than the speed of light.
The laws of physics are the same for anyone moving at a constant velocity.
Relative velocity is additive within the normal range of speeds.
The Michelson-Morley Experiment showed that the speed of light is constant regardless of the observer's motion.
The Lorentz factor, gamma, is used to calculate relativistic effects on time and distance.
Time dilation is the slowing of time at high speeds, near light speed.

General Theory of Relativity (GTR)

GTR is a more general version of the Special Theory of Relativity.
The force of gravity can be viewed as a warpage of space-time.
The Equivalence Principle states that you cannot distinguish between gravity and acceleration.
GTR has applications in GPS systems.

Radiation and the EM Spectrum

Wavelength, spectrum, nanometer, and angstrom are key terms related to radiation.
Intensity (brightness) is determined by the amplitude squared in wave form and by the number of photons per second in particle form.
Radio waves and visible light can fully penetrate the Earth's surface.
Ozone blocks UV, X-rays, and gamma rays.
Water vapor and carbon dioxide block infrared radiation.

Telescopes

Light Gathering Power (LGP) is the most important property of a telescope.
Resolving Power (RP) is the ability to see fine detail or resolve two close stars.
Magnifying Power (MP) is the ability to enlarge an image.
The f-ratio determines the brightness of a telescope.
Large LGP, medium f-ratio, small RP, and low MP are desirable.

Primary Lenses and Mirrors

Focal length, seeing, and light pollution are important factors in telescope performance.
Refractive telescopes use lenses.
Reflective telescopes use mirrors.
Hybrid telescopes are a combination of both lens and mirror systems.

Telescope Mounts

Alt-az mounts move the telescope up and down (altitude) and left and right (azimuth).
Dobsonian mounts are a type of alt-az mount.
Equatorial mounts are designed to track the Earth's rotation.

Refractive and Reflective Telescopes

Networks of telescopes combine to create a larger effective telescope.
Lens problems include chromatic aberration and light absorption.
Reflecting telescopes are advantageous because they:
Have no chromatic aberration
Can be larger
Are less expensive
Allow for a variety of focal lengths.

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Description

This quiz covers fundamental concepts in astronomy, including stellar distances using parallax, proper motion of stars, and Newton's Laws of Motion. Test your understanding of how these principles apply to celestial objects and their movements in the universe.