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39 Cards in this Set
- Front
- Back
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An astronomical unit (AU) is |
Earth's average distance from the sun (150 million km) |
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Could we see 18 billion light years away? |
No, because it would be beyond the bounds of our observable part of the universe |
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When we look further away in distance |
We look further back in time |
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Our distance from the galactic center is about |
28000 light years |
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The Andromeda Galaxy is |
Moving towards us |
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The fact that all galaxies are moving away from us, with more distant galaxies moving faster, helped us to conclude that |
The universe is expanding |
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Stonehenge is connected to astronomical events, because |
It marks the seasons by marking the directions to sunrise and sunset at summer and winter solstice |
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Ptolemy explained |
Retrograde motion in a geocentric model through planets moving on epicycles (small circles upon large circles) |
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Erathostenes measured |
The circumference of the earth from the shadow that a tower casts on a specific day |
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Tycho Brahe's most important contribution to science was |
His extremely careful observations of planetary orbits |
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The phases of Venus as a confirmation of the heliocentric model were discovered by |
Galileo |
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We say that a planet has a highly eccentric orbit when |
It is much close to the sun in some parts of its orbit than other parts |
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An accepted scientific theory must |
Not contradict experimental observations Make falsifiable predictions that can be tested in experiments Explain a large range if observations |
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Why is a sunflower yellow |
It reflects yellow light |
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Red light has a longer wavelength than blue light. Red light therefore has |
Lower energy and lower frequency |
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Compared to the atom as a whole, the atomic nucleus |
Is tiny and has most of the mass |
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Some atoms with six protons in the nucleus have six neutrons, while others have seven or eight neutrons. These different kinds of atoms are |
Different isotopes of one and the same chemical element |
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Electromagnetic radiation consists of |
Oscillating electric and magnetic fields |
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If you heat a metal until it glows, it's spectrum will be |
A thermal radiation spectrum |
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Radio waves are |
A form of electromagnetic radiation |
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The line spectrum of a star can tell us something about |
It's chemical composition It's radial speed relative to us It's rotation speed NOT it's mass |
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Compared to our sun, a star whose spectrum peaks in the blue is |
Hotter |
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A spectral line that appears at a wavelength of 321 nm in the lab appears at a wavelength of 313 nm in the spectrum of a distant object. Astronomers day that the objects spectrum is |
Blueshifted |
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We can measure the temperature of a star from its thermal radiation spectrum |
using both the position of the peak(max intensity) or the total light output |
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Angular resolution is |
The smallest angle over which we can tell that two dots (or two stars) are distinct |
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Astronomers do not use telescopes for |
Dendrology |
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A spectral line in the lab has a wavelength of 528 nm. The same spectral line from a star has a wavelength of 521 nm. The star is |
Moving towards us |
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The following two wavelength ranges of the electromagnetic spectrum can penetrate the atmosphere |
Visible and radio |
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The emission lines from star A are narrower than the emission lines from star B. This implies that |
Star A is rotating slower than star B |
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Suppose that two stars A and B in the sky are separated by 0.5 arcseconds. You want to look at the stars with a telescope with an angular resolution of 0.1 arcseconds. What will you see? |
Both a and b as separate stars |
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The diffraction limit is a limit on |
The angular resolution of a telescope |
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The Hubble space telescope obtains higher resolution images than most ground based telescopes because |
It is above earth's atmosphere |
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Important factors for selection of a large telescope site |
Calm, not too windy At high altitude Dry for little could coverage |
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The twinkling of stars is caused by |
Motion of air in our atmosphere |
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How many planets rotate around their axis in the same direction as earth |
Most |
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Why did the solar nebula heat up as it collapsed |
As the cloud shrank, it's gravitational potential energy was converted into thermal energy |
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The solar nebula was 98% |
Hydrogen and helium |
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Why didn't a terrestrial planet form at the location of the asteroid belt |
Jupiter's gravity prevented planetesimals from accretingw |
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What is the frost line |
It is a line in the accretion disc around a star Hydrogen compounds can only freeze outside of this line |
