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44 Cards in this Set

  • Front
  • Back

What is a light year, and what does it describe?

The distance travelled by light in one Earth year : distance

Why do Astronomers think our Universe started with a "Big Bang"?

The galaxies are getting further apart, so a long time ago they must have been together.

Why do far away galaxies look young?

The light from far away galaxies was emitted a long time ago when they were young.

Approximately, how old is the Universe?

14 billion years (14,000,000,000)

What is the "local group"?

The set of nearby galaxies, spanning about 10 million light-years

What is your "address" in the Universe, in the correct order?

you, Earth, Solar System, Milky Way Galaxy, Local Group, Universe

About where is our solar system located within the Milky Way Galaxy?

about two-thirds the way from the centre of the galaxy to the outskirts of the galactic disc

What was the early Universe made of?

hydrogen, and helium, with very little heavier elements

What is the Sun mostly made of?

hydrogen and helium

Astronomers define any element but hydrogen, helium, and lithium as "metals". Earth's crust is mostly made of these "metals". Where did these come from?

They were formed by fusion processes in stars.

Why can't we see further than about 14 billion light-years?

The light has not yet had time to reach us.

There are approx. 100 billion galaxies in the observable Universe. If each galaxy has 10 billion stars, and each star has a habitable planet, how many habitable planets are there in the Universe?

1 sextillion ( 10^12)

How did an ancient Egyptian "hour" compare to the one we use today?

it varied in length depending on the seasons.

How did Eratosthenes determine the size of the Earth?

measuring the distance between two cities and considering the position of the Sun at noon on the summer solstice in both places.

Ptolemy created an astronomical model that allowed for very accurate predictions of positions of stars and planets. Why is it no longer used today?

His model was Earth centric

During the Dark Ages, in Europe, a time where scientific thinking was rapidly regressing, where did the majority of scientific advancement take place?

The Middle East

What was Nicholas Copernicus' most notable contribution to modern day Astronomy?

He proposed a simplified Heliocentric model of the solar system.

How did Tycho Brahe contribute to the field of Astronomy?

1.He recruited Kepler as his assistant for analyzing observational data.


2.He determined that comets and novae occur much further away than the moon.


3. He took extremely detailed and accurate measurements of the positions of heavenly bodies.

How did Johannes Kepler contribute to Astronomy?

He determined that planets move in ellipses, and proposed Kepler's Law of Planetary Motion.

Kepler's First Law tells us that:

1. a planet moves in an ellipse with the Sun at one focus.


2. a planet moves in a circle with the Sun at the centre.

Kepler's Second Law tells us that a planet with an elliptical movement will:

move more slowly when it is further from the Sun.

Kepler's Third Law relates the characteristic of a planet:

average distance and period


a^3=p^2

How did Galileo contribute to modern Astronomy?

1. refined the telescope for use as a scientific instrument.


2.discovered the largest 4 moons around Jupiter


3. showed that Venus actually rotated around the sun, not the Earth.

Watt is a What? (What is a Watt)

a unit of power

What property of light determines it's "colour"?

wavelength

A camera flash appears white in color. What does this tell you about the light emitted?

It contains a mixture of light from across the visible spectrum.

A particle of light (a photon) hits an electron. All of the photon’s energy is turned into kinetic energy in the electron, and no photons are left after the collision. What light/matter interaction has taken place?

Absorption

Which of the following is false?


a) When you listen to the radio, you are using your ear to detect radio waves.


b) Humans cannot detect infrared radiation, as it is not in the visible spectrum.


c) The sun is similar to a black body, so we can tell its temperature from its spectrum.


d) Most of the volume of an atom is composed of empty space

When you listen to the radio, you are using your ear to detect radio waves.

Which of the following phases of a material is the hottest?


a) Liquid


b) Plasma


c) Solid


d) Gas

plasma

A transparent material

Transmits light very well

Why is grass green

c) It reflects green light and absorbs all other colors


d) It scatters green light

An atom is missing an electron in one of its electron energy levels, and another electron moves in to fill the space. Which transition would emit the most energetic photon?

An electron drops in energy from the 4th energy level to the lowest (first) energy level.

You are looking at a tungsten lamp, which emits a very smooth, continuous spectrum in the wavelengths you are looking in. Suddenly, a dense cloud of hydrogen passes between you and the lamp. How does the spectrum change?

You start to see hydrogen absorption lines.

Which effect makes emission lines from far away galaxies look redder than they should, and why?

The Doppler effect; the galaxies are receding from us, so their light looks redder

You find an ion of a rare isotope of the (hitherto undetected) element Unobtanium while on a family vacation to Pandora. The nucleus of this isotope has 215 protons and 285 neutrons, and it has 213 electrons surrounding it. Which of the following are the correct atomic number, weight and charge (in that order)?

215, 500, +2


An optometrist finds that the focal plane of your eye does not coincide with your retina when you look at objects that are far away from you. What problem would you notice with your eyesight?


everything you see is blurry.


A motorcycle and a car are driving side by side on a highway at night. The motorcycle’s headlight is twice as bright as each car headlight, so that the total light coming from each vehicle is the same. You are standing far enough from the vehicles that the angular separation of the car’s headlights is much lower than the angular resolution of your eye. Can you tell which vehicle is which?


No, each will appear as a point source of equally bright light.

What is the main benefit of using CCD cameras over standard film cameras?

CCDs detect a higher fraction of photons

If you have a camera (but not a spectrometer) hooked up to your telescope, which of the following experiments can you not perform?

Find out how fast a star is rotating

If you have a spectrometer attached to your telescope, and are not capable of direct imaging, which of the following experiments can you not perform?

Determine the size of a galaxy.

Which of the following experiments is least likely to yield useful results?

A sea-level X-ray imaging telescope

Which of the following is not a good reason to launch a telescope into space?

It is closer to the objects it is measuring.

Why must you cool an extreme infrared space-based telescope down to observe faint objects?

A warm telescope will emit its own infrared spectrum

Which of the following is not an advantage of reflection (mirror) telescopes over refraction (lens) telescopes?

Reflectors collect more light than a refractor of the same size