Quiz 2

Question 1

Existence of dark matter

Answer 1

Galaxies simply do not have enough mass to be held together by gravity
Based on our observations, stars would be scattered randomly throughout the universe based on the gravity of observable matter
Dark matter exists - weird, mysterious, and probably vital to the existence of the universe as we know it

Question 2

Irregular galaxies

Answer 2

These galaxies have an irregular shape
fesult of the collisions of galaxies
generally contain a complex mix of interstellar gas and dust, young stars, and old stars

Question 3

Spiral galaxies

Answer 3

These galaxies are disk-shaped width either a round central hub (unbarred) or a hub shaped like a bar (barred)
They rotate with spiral arms that contain interstellar dust and gas, as they rotated gas and dust gets swept into nebulas, promoting star formation and an abundance of young stars

Question 4

Elliptical galaxies

Answer 4

little to no structure, rotation, or interstellar matter
minimal star formation and dominance of the long lived, red stars
ellipsoid-shaped
most common type of galaxy

Question 5

Chicxulub crater

Answer 5

300 km diameter ringed basin
About 65 million years old
Buried beneath Yucatan Peninsula and Gulf of Mexico
evidence of asteroid impact that killed dinosaurs

Question 6

DART mission

Answer 6

wanted to knock an asteroid off its course, was successful
Systems used in DART could be used to knock an asteroid off course if it is going to hit Earth

Question 7

What are the three types of meteorites?

Answer 7

Stones, irons, and stony-irons

Question 8

Characteristics of stones (stone meteorites)

Answer 8

largest group, and they once formed part of the outer crust of a planet or asteroid

Question 9

Characteristics of irons (iron meteorites)

Answer 9

once part of the core of a long vanished planet or large asteroid
believed to have originated within the Asteroid Belt

Question 10

Characteristics of stony-irons (stone and iron meteorites)

Answer 10

very rare ( less than 2% of all known meteorites)
roughly equal amounts of nickel-iron and stone
thought to have formed at the core/ mantle boundary of their parent bodies

Question 11

What is the kinetic energy equation

Answer 11

KE =(½)(m)(v^2)

Question 12

Meteoroid

Answer 12

A small piece of asteroid or other debris in the solar system, measures less than 1 meter to be considered a meteoroid (but must be at least as large as a small grain)

Question 13

Meteor

Answer 13

The term “meteor” refers to the fiery aerial display created by a falling meteoroid or asteroid

Question 14

Meteorite

Answer 14

A meteorite is if the meteoroid survives the atmosphere and lands on Earth

Question 15

Asteroid

Answer 15

Rocky/metallic objects that orbit the sun
Mostly made of rock
typically cratered and irregularly shaped
Most asteroids are within asteroid belt

Question 16

Nebula

Answer 16

a cloud of interstellar dust and gas

Question 17

Planetesimal

Answer 17

one of the small bodies that formed from the solar nebula and eventually grew into protoplanets

Question 18

Protoplanetary body

Answer 18

a relatively large clump of material, formed in the early stages of solar-system formation, which later formed into planets

Question 19

Nuclear fusion

Answer 19

nuclear process that releases energy when lightweight nuclei combine to form heavier nuclei

Question 20

terrestrial planet

Answer 20

any of the planets Mercury, Venus, Earth, or Mars, or a planet similar in size, composition, and density to Earth. A planet that consists mainly of rocky material

Question 21

Kepler’s 1st law

Answer 21

The orbit of every planet is an ellipse with the Sun at one of the two foci (focal points)

Question 22

Kepler’s 2nd law

Answer 22

A line joining a planet and the Sun sweeps out equal area during equal intervals of time (planet is faster when closer to the Sun and slower when further)

Question 23

Kepler’s 3rd law

Answer 23

The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit (the further from the Sun, the longer a planet’s revolution, year is proportional to th distance from the Sun)

Question 24

Ellipses

Answer 24

elongated circles, the set of points such that the sum of the distance to the foci for any point on the ellipse is constant

Question 25

Eccentricity

Answer 25

describes how elongated an ellipse is, ranges from 0 to 1 Higher eccentricity means an ellipse is more elongated, farther from a circle

Question 26

Calculating eccentricity

Answer 26

Eccentricity = distance between foci / length of major axis Higher eccentricity means an ellipse is more elongated, farther from a circle

Question 27

Aphelion

Answer 27

the point in an object’s orbit when it is farthest from the Sun

Question 28

Perihelion

Answer 28

the point in an object’s orbit when it is closest to the Sun

Question 29

What a comet is

Answer 29

Small icy bodies that originate from the outer edges of our solar system Comets have low densities (< 1) Orbit the sun, some orbits as short as 100 years or less, some orbits upwards of 30 million years Orbits follow Kepler’s laws

Question 30

What are the parts of a comet?

Answer 30

nucleus, coma, 2 tails

Question 31

parts of a comet and how they form

Answer 31

Nucleus - about 10km, center made of frozen gases, mixed with bits of rock, at the center may be rock Coma - 10^3 to 10^5 km, forms when comet is closer to the Sun, gases sublimate and form a weak atmosphere, making coma grow Comets have 2 tails, 10^5km to 1 AU long, one formed by dust and the other from gas, solar winds push dust and gas away from coma to form tails

Question 32

Where comets come from (short and long period comets)

Answer 32

Comets are thought to be the left over debris from during the time of formation of the solar system. Comets have shorter orbits (~200 yrs or less) known as short period comets, and longer ones (~30 million years), known as long-period comets Short period comets come from Kuiper Belt Long period comets come from Oort Cloud, long period comets are evidence for Oort Cloud’s existence

Question 33

Process of Outgassing

Answer 33

The process by which gases that are frozen or trapped inside an object are released, heat from the sun allows gases to escape from a comet as it nears its perihelion Happens when distance comets made of ice and gas approach the Sun, highly eccentric orbit means they get very close

Question 34

orbits of comets

Answer 34

Comets have higher eccentricity Focal points are further from each other and closer to the edges, the difference between aphelion and perihelion is large, getting really close to the Sun and really far from the Sun based on where it is in its orbit Elliptical in shape Not oriented to ecliptic plane, randomly oriented Orbits follow Kepler’s laws

Question 35

evidence for 10km asteroid impact (dinosaur killer)

Answer 35

Evidence for 10 km asteroid impact in Worldwide 65 million yr old clay layer with: Iridium (element #77) rare in crust, but in clay Shocked quartz—indicates heat & pressure Soot—global wildfires

Question 36

what did the impact of the 10km asteroid have on Earth

Answer 36

Impact caused extinction Disappearance of 70% species from the fossil record, including dinosaurs

Question 37

What happens when a large (10km) asteroid or comet strikes

Answer 37

Object explodes (energy = billion megatons) on impact vaporizes a portion of crust Molten rock is thrown into atmosphere, it falls back down as a fiery rain igniting forests Lighter dust stays suspended=>dark & cold Photosynthesis & food chain disrupted Soot, shocked quartz, iridium dust settles creating 65 million year old clay layer exposed at over 100 places on Earth

Question 38

earth impacts

Answer 38

Small bodies can produce very large impact craters because velocity has such a big impact, it is squared in the equation Meteor crater, Arizona 50000 years old Projectile was 50 meter diameter, metallic asteroid Crater diameter is 1.2km, 200m deep