EXAM 1 study set

Which is the largest unit of distance?

LY, the distance light travels in one years

In our universe, gravity is responsible for structure on several scales.  The largest scale structures in our universe are

Superclusters of galaxies

What cosmic address would you give, what would you use to make this being understand where you call home?

Virgo supercluster, Local Group, Milky way, Solar System, Earth

Astrobiology is

a combination of astronomy. biology, chemistry, geology seeking to reveal connections between living organisms and the places where they reside.

A habitable world is

a planet that may or may not have life, but that has environmental conditions under which it seems that life could arise or survive

People have long been interested in life beyond Earth.  What is different today that makes this possibility seem scientifically reasonable?

 New discoveries in planetary exploration and biology make it plausible that simple life could exist elsewhere.

Approximately how many stars are there in the Milky Way galaxy?

Hundred billion

The total number of stars in the observable universe is roughly equivalent to

the number of grains of dry sand in all the beaches on Earth

What is the distance of the horizon of the observable universe?

~14 billion LY

When we say that the universe is expanding we mean that

 the average distance between galaxies is growing with time.

A trillion stars is

 1.0 x 10¹²

About how many stars are in our Milky Way?

1.0 x 10¹¹

What is a realistic estimate for the number of stars in our universe if there are 10 billion galaxies= 1.0x10¹¹ galaxies

 1.0 x 10²²

What is the Hubble telescope?

 A space telescope in Earth orbit above the atmosphere.

What is the James Webb telescope?

A space telescope in orbit about the Sun at the Lagrange point 2 (L2)

What innovations does the James Webb telescope have over previous space telescopes? 

•  a sunshield the size of a tennis court

• Hexagonal lightweight Beryllium mirrors coated with gold.

What is a "deep field" image?

An image obtained by looking at a supposedly empty area of the sky over a long period of time.

The result of the "deep field" images from both the Hubble and Webb Telescopes  are:

 the discovery of many more faint galaxies that make up our universe.

Compared to the Hubble Space Telescope, the Webb space telescope

is an infrared telescope which is able to see more distant objects redshifted to infrared light from the expansion of the universe

The Voyager space mission

was comprised of two spacecraft which visited Jupiter, Saturn, Uranus and Neptune and has since left the solar system.

The solar system formed from the gravitational contraction of an interstellar cloud of gas.  Based on the patterns of motion, what must have been the shape of the cloud at the time the planets formed?

circular disk

terrestrial planets are

small, made mostly of rock and iron with high densities and found close to the Sun

jovian planets are

large, made mostly of gases and liquids with low densities and found far from the Sun

• jupiter

• uranus

• saturn

• neptune

Between the orbits of the planets Mars and Jupiter we find

the asteroid belt

Out immediately beyond the orbit of the planet Neptune we find

kuiper belt

In the outer regions of the solar nebula where temperatures were low

in addition to rock and iron, hydrogen compounds also condensed as ices

Which of the following materials present in the solar system had the highest condensation temperatures?

metals

According to the nebular theory for the formation of the solar system,

planets should be rotating in the same direction as they orbit the Sun

Planetesimals are

about 10 to 100 km in size

What is the difference between a comet and an asteroid?

 A comet is a planetesimal that is made mostly of ices and an asteroid is made mostly of rocky material.

The text mentions that we should expect exceptions in the formation of the solar system from the nebula.  An exception that has been observed is

Uranus’s tilt

who are the dwarf planets

• ceres

• pluto

A Japanese space mission has determined that the asteroid Itokawa

 is a loosely held together rubble pile

A doughnut shaped cloud of icy planetesimals beyond the orbit of Neptune is

kuiper belt, and where short period comets (Halley) are from

long period comets are from oort cloud

As it formed, the solar nebula rotated faster and faster because

 the cloud shrank and it conserved angular momentum.

The formation of snow flakes is an example of the process called

accretion

what is accretion

Accretion is the gradual accumulation of matter by gravitational attraction, forming larger objects. It occurs in various astrophysical processes, such as the formation of stars and planets.

The Oort cloud is thought to have originated  from

 planetesimals which were tossed out of the solar system by the Jovian planets

Where is the solar nebula today?

 The solar wind from the new Sun blew it away.

Perseverance Rover

search for signs of microbial life
characterize planets climate and geology
pave way for human exploration of the planet