ESCI 420 exam 1

Rank the following in terms of decreasing semi-major orbital axis:

Mercury, Mars, Pluto, Uranus, Jupiter Pluto, Uranus, Jupiter, Mars, Mercury Mercury, Mars, Uranus, Jupiter, Pluto Jupiter, Uranus, Mars, Mercury, Pluto Pluto, Uranus, Jupiter, Mars, Mercury

The concept of gravity acting instantaneously (meaning, faster than the speed of light) between objects was proposed by which famous physicist?

Newton Einstein Greene Hawking Newton

Place in order, from youngest to oldest (1 - 4), the sequence of the evolutionary stages of a Sun-like star:

T-Tauri, Main Sequence, Red Giant, White Dwarf Main Sequence, White Dwarf, Red Dwarf, T-Tauri White Dwarf, T-Tauri, Red Giant, Main Sequence Red Giant, T-Tauri, White Dwarf, Main Sequence T-Tauri, Main Sequence, Red Giant, White Dwarf

Which of the following statements about the first few minutes of the Big Bang is true?

The universe was transparent. The universe was very cool. Hydrogen fused into helium. Galaxies began to form. Stellar cores began to form. ??

From what evidence do astronomers deduce that the universe is expanding?

They can see the disks of galaxies getting smaller over time. They can see a redshift in the spectral lines of distant galaxies. They can see the edge of the universe moving away from us. They can see distant galaxies dissolve, pulled apart by the expansion of space. ??

The 'supernova trigger' hypothesis suggests that...

stellar formation could be initiated by molecular cloud collapse as a result of a nearby supernova. supernova seed nearby stars with heavy elements that cause those stars to also collapse. a star that collapses into a supernova cycles between red supergiant and neutron several times before settling into a black hole. a supernova will pull nearby smaller stars into its core before exploding. stellar formation could be initiated by molecular cloud collapse as a result of a nearby supernova.

One credible explanation for why the planets near the Sun are composed mainly of rock and iron is that:

the Sun's gravity only acts on solid materials, and only iron and rock condensed into a solid. the Sun is made mostly of iron, so gas ejected from its surface cooled and condensed to form iron-rich planets. the high temperatures in the inner part of the Solar System prevented ices and gases from condensing near the Sun. the Sun's magnetic field attracted all the iron in the young Solar System into the region around the Sun. the high temperatures in the inner part of the Solar System prevented ices and gases from condensing near the Sun.

Inflationary theory does not explain

why the cosmic microwave background has a nearly uniform temperature in all directions. why the curvature of the universe appears to be nearly flat. the sizes of small temperature differences observed in the cosmic background radiation. what happened before the Big Bang. what happened before the Big Bang.

The Virial theorem quantifies the balance between ____ and ____ energies in terms of predicting when a molecular cloud will begin to collapse to make a star.

gravitational and thermal mass and compositional centrifugal and centripetal fusion and fission nuclear and gravitational gravitational and thermal

After several minutes of the Big Bang, two main elements were present and still make up the bulk of the interstellar medium near our galaxy today. These are:

hydrogen and carbon. hydrogen and helium. oxygen and lithium. oxygen and nitrogen. hydrogen and helium.

The Doppler shift method for detecting the presence of exoplanets is best able to detect

low-mass planets near the star. low-mass planets far from the star. massive planets far from the star. massive planets near the star. massive planets near the star.

Current scientific evidence indicates the age of the universe is approximately in which range?

1 to 2 million years old 500 to 700 million years old 4 to 5 billion years old 13 to 15 billion years old 13 to 15 billion years old

Human eyes are most sensitive to which wavelength?

550 cm 550 mm 550 nm 550 microns (um) 550 nm

Suppose a thousand solar masses-worth of interstellar gas forms into a group of stars of all masses. If you came back a billion years later, where would that gas (matter) now be?

Almost all in white dwarfs, black holes, and neutron stars. Most of it collected into the heaviest stars that formed. Nearly all of it would have turned back into interstellar gas except for a small amount in black holes. Much still in the same low-mass stars, but some back as interstellar gas or later generations of stars. Much still in the same low-mass stars, but some back as interstellar gas or later generations of stars.

How long after the Big Bang did the Universe become transparent to photons?

Approximately 1 second About 10 seconds Around 380,000 years At several hundred million years Around 380,000 years

Which orbital property is most strongly responsible for Earth's seasons?

Axial tilt Period Eccentricity of orbit Counter-clockwise rotation Axial tilt

Sequence the following important processes of planetary formation. Note you need to choose the one that lists them in the right order, starting with the earliest.

collisional accretion, gravitational collapse, chemical condensation, snowflake accretion gravitational collapse, collisional accretion, chemical condensation, snowflake accretion chemical condensation, gravitational collapse, snowflake accretion, collisional accretion chemical condensation, snowflake accretion, collisional accretion, gravitational collapse chemical condensation, snowflake accretion, collisional accretion, gravitational collapse

If the moon was twice as distant from the Earth as it presently is, its gravitational attraction to Earth would:

double. quadruple. be halved. be quartered. remain unchanged. be quartered.

If the moon were twice as massive as it presently is, its orbital period around Earth would:

double. quadruple. be halved. be quartered. remain unchanged. remain unchanged.

Venus as a whole radiates as a blackbody with average temperature of 230 K. Use Wien's Law to calculate the wavelength of the strongest radiation for this blackbody. * Note - you would want to be aware of to which part of the electromagnetic spectrum this wavelength corresponds. The wavelength regions listed below are all accurate for the numbers given...you're only calculating the right number right now.

120 nm, UV 12 microns, IR (but closer to visible than microwave) 12 mm, microwave 12 m, radio wave 12 microns, IR (but closer to visible than microwave)

Let's try an escape velocity problem - what velocity would Earth's moon need to attain in order to break free from orbiting Earth? Note: this is not the same calculation as what velocity an object on the surface of the Moon would need to escape the gravitational force of the Moon. Also, we are not considering also escaping the Sun (which would require more speed and a more complex equation...that would be called escape from the Earth-Sun system). Just free the Moon from the Earth. Use these numbers: Moon orbital period: 27.3 days Moon orbital path length: 2,418,000 km (assume it's circular for convenience) Hint: first calculate the orbital speed of the Moon in km/s

2.38 km/s 11.2 km/s 1.03 km/s 1.45 km/s 1.45 km/s

Short-lived isotopes in the early Solar System allow us to date the relative timescales of early processes, like when different types of materials condensed (which helps us refine our models of Solar System formation). Which of the following is not a short-lived isotope? Note that we can write the short-lived isotope carbon 14 as either 14C or C-14. The latter notation is used below because Canvas is not permitting superscripts in the answer fields.

Al-26 U-238 I-129 Mn-53 U-238

Where is the 'snow line' of our Solar System located?

Between the Sun and Mercury Between Venus and the Earth Between Mars and Jupiter Between Neptune and Pluto Between Mars and Jupiter

Which of Kepler's laws explains why comets on high eccentricity orbits spend most of their orbital period far from the Sun?

First Law Second Law Third Law None of them; this is unrelated to Kepler's laws Second Law

Which of the following is the least significant process in the disk around the star where planets form?

Gravitational attraction Spinning Nuclear fusion Heating Nuclear fusion

Suppose we could measure one property of a protostar. Which property would tell us most about its future evolution?

Its temperature Its radius Its color Its luminosity Its mass Its mass

What is meant by 'inflation' of the early universe?

The force of gravity suddenly grew stronger in the past. Protons expanded to enormous sizes, making new stars. The universe expanded enormously in a very brief time. The number of galaxies rises dramatically with distance. Distant galaxies are much larger than nearby galaxies. The universe expanded enormously in a very brief time.

Radiating objects emit spectra that can be studied to learn about the object's _______.

area temperature density chemical content (a) and (b) (b) and (c) (b) and (d) (b) and (d)

Which of the following is not a possible aftermath or byproduct of a supernova?

black holes neutron stars electron stars triggered formation of another star electron stars

Arrange the following in order of increasing density:

molecular clouds, interstellar medium, stars, neutron stars, black holes black holes, neutron stars, stars, interstellar medium, molecular clouds neutron stars, stars, black holes, molecular clouds, interstellar medium interstellar medium, molecular clouds, stars, neutron stars, black holes interstellar medium, molecular clouds, stars, neutron stars, black holes

Sequence the following in increasing wavelengths:

radio, ultraviolet, infrared, visible, X-rays X-rays, ultraviolet, infrared, radio ultraviolet, X-rays, infrared, radio radio, infrared, visible, ultraviolet, X-rays X-rays, ultraviolet, infrared, radio

Kepler's third law:

relates the duration of a planet's orbit to the size of its orbit relates a body's mass to its gravitational attraction. allowed him to measure the distance to nearby stars. allowed him to predict when eclipses occur. relates the duration of a planet's orbit to the size of its orbit

The Hubble constant for the universe 5 billion years in the future will be:

the same as it is today. greater than it is today. smaller than it is today. No answer text provided. ??

The numerous craters we see on the solid surfaces of so many Solar System bodies are evidence that:

the young Sun was so hot that it boiled these bodies. they were bombarded in their youth by many solid objects. they were hot in their youth with widespread volcanoes. all the planets were once part of a single, very large, and volcanically active mass that broke into many smaller pieces. they were bombarded in their youth by many solid objects.

If you lived in a galaxy far away from the Milky Way, your red-shift measurements would show that galaxies move

toward you out to the Milky Way; away at larger distances. away from the Milky Way but toward you. away from you in the same way that Hubble found. toward you in half the sky, away in the other half. away from the point where the Big Bang occurred. away from you in the same way that Hubble found.