University of Minnesota AST 1001 FINAL EXAM!!!!!!!!!!!!!!

Astronomical Units (AU)

The average distance from the Earth to the sun

Light Years

the distance in which light travels in one year

The Universe is ___ years old

13.8 Billion

Earth is ___ years old

4.5 Billion

constellation

a region of the sky marked by it’s stars

the celestial sphere

an old theory made by the greeks that imagined the universe as a sphere with the earth at its center.

Zenith

local coordinate. always above you

horizon

great circle that passes through the left and right sides of the celestial sphere

angular size

how much an object spans in our field of view. farther = smaller

angular distance

the measure of the angle between the orientation of two straight lines

Circumpolar stars

stars that never set and are always visible

solar eclipse

when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth,

annular eclipse

occurs when the moon is farthest away from the earth in its orbit. this makes the moon look smaller.

partial solar eclipses

visible if you are in the penumbra of the shadow.

total solar eclipse

can only occur if you are at the exact spot within the moon's umbra

stellar parallax

the apparent shift of position of any nearby star against the background of distant stars.

Epicycles

theory proposed by Ptolomy that pictured planets circling many miniature circles along their orbits in an attempt to explain retrograde

____ discovered elliptical orbits

Keplar

____ did not invent the telescope, only improved it’s design.

Galileo

hypothesis

testable explanation to a question

theory

supported by large body of scientific evidence

law

something that, under the presented circumstances, will always happen without fail

gravity’s inverse square law

as you double the distance, the force of gravity becomes one-fourth as strong.

mass

the total amount of matter in an objec

weight

the total amount of gravity acting on an object

Newton’s first law

An object will have a constant velocity unless acted upon by a force

Newton’s second law

Force = Mass x Acceleration

Newton’s third law

For every action, there is an equal and opposite reaction

Keplar’s first law

Elliptical orbits with the sun at a focus

Keplar’s second law

objects move faster when closer to the sun, slower when farther from it

keplar’s third law

a planet's orbital period is proportional to the size of its orbit

Escape velocity

the amount of movement needed to escape orbit

What causes tides?

differential gravity from sun and moon

redder waves

longer wavelength, lower frequency, lower energy

inverse square law

1/distance²

Blackbody radiation

an idealized object that absorbs all electromagnetic radiation it comes in contact with

Wien’s law

lambda = 3×10^6 / T

Stefan-Boltzmann Law

total light is proportional to area and T^4

Continuous spectrum

an emission wavelength that has a continuous wavelength

Refracting telescopes

most attributed to Galileo. Similar to a large lens. lenses collect light

Reflecting telescopes

most attributed to Newtwon. Similar to a large mirror that reflects light into an eye peice.

which rays are not visible from earth

Gamma, X-ray, UV, IR, microwave, long radio

which rays are visible from earth

Visible, radio

blackbody radiation

energy radiated by any object or system that absorbs all incident radiation

absorption spectrum

things in front of a light source, specific wavelengths blocked

emission spectrum

thin gas being heated, majority of wavelengths blocked

Doppler effect

the change in wave frequency during the relative motion between a wave source and its observer. Moving away = redder, moving towards = bluer

IO

volcanic, tidal heating

Europa

ocean beneath a crust of ice, tidal heating

Ganymede

largest moon, possible subterranean ocean

Callisto

heavily cratered, possible subterranean ocean

Density differentiation

More dense materials are brought to the bottom

magnetic field

The cooling and crystallization of the core stirs up the surrounding liquid iron, creating powerful electric currents that generate a magnetic field stretching far out into space.

Where did life start

in the oceans

what does life require

energy, nutrients and liquid water

Drake equation

a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.

What qualifies a dwarf planet

a planet that has not cleared the area around its orbit,

the parts of the comet

coma, ion tail, dust tail

coma

the “aura” of a comet

transit method

the observation of a slight dimming of a star's light when a planet passes in front of it, as seen from Earth, in order to discover exoplanets

doppler method

detects exoplanets by observing the gravitational interaction between a star and its orbiting planets, causing a periodic shift in the star's spectral lines.

Where on the H-R Diagram is the sun

on the main sequence

a star on the main sequence is ALWAYS

fusing hydrogen into helium in it’s core

nuclear reaction in the sun produces

neutrinos, positrons

neutrino

very small aprticle emitted by the sun. thousands pass through us each second but they remain undetectable

solar neutrino problem

the significant discrepancy between the predicted and observed flux of neutrinos coming from the Sun. The resolution came with the discovery of neutrino oscillation, demonstrating that neutrinos change flavors as they travel from the Sun to the Earth

gravitational equilibrium

the balance between the inward gravitational force pulling matter inward and the outward pressure pushing matter outward in a celestial body.

convection

the process by which heat is transported from the Sun's interior to its outer layers and eventually into space.

solar cycle

a recurring period of changes in the Sun's activity, explains the variation in the number of sunspots on the Sun's surface

how long is the solar cycle

11 years

radiation released by the sun can affect:

aurora, satellites, gps, power grid

Parallax forumla

d = 1/p (d is the distance to the star, p is the parallax angle.)

parsec

the distance at which a star exhibits a parallax angle of one arcsecond as observed from Earth

apparent magnitude

how bright an object appears

absolute magnitude

how bright an object is at 10 parsecs

when referring to magnitudes, are bigger or smaller numbers brighter?

smaller

spectroscopic binary

a binary star having components that are not sufficiently separated to be resolved by a telescope,

visual binary

gravitationally bound binary star system that can be resolved into two stars

eclipsing binary

a type of binary star system in which the two stars orbit in such a way that, as seen from Earth, one star periodically passes in front of the other, causing a decrease in observed brightness.

how do we get the masses of almost any celestial object?

Keplar’s third law

what determines everything about a star?

mass

0.08 - 8 mSun

White Dwarf

8-40Msun

neutron star/pulsar

40-100Msun

black hole

<0.08 Msun

brown dwarf

nova

 flashes of material as the star accretes things. EXCLUSIVE TO BINARY STAR SYSTEMS

Type i supernova

When a white dwarf accretes matter from its companion star and reaches a critical mass, a runaway nucleur fusion reaction occurs

type ii supernova

These supernovae are associated with the collapse of massive stars at the end of their life cycles, resulting in a black hole. we CANNOT tell when it will explode

neutron star

an extremely dense and compact astronomical object that forms as the remnant of a massive star after a supernova explosion

pulsar

a highly magnetized, rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. If these beams of radiation intersect Earth as the star rotates, astronomers observe periodic pulses of radiation

spiral galaxy

type of galaxy with Disk, spiral arms, central bulge, sometimes have a bar, Active star formation

elliptical

galaxy with a round shape, old stars

how do we get galaxy rotation curves

from doppler shifts

where can supermassive black holes be found

at the center of every galaxy

more massive galaxies have ____ supermassive black holes

bigger

quasars

black holes that are actively accreting massive amounts of matter, releasing enormous amounts of energy in the process and a lot of light

starburst galaxy

a type of galaxy undergoing an exceptionally high rate of star formation

dark energy

the driving force behind the accelerated expansion of the universe

dark matter

a form of matter that does not emit, absorb, or interact with electromagnetic radiation, making it invisible to telescopes and other instruments that detect light

cosmic microwave background

the faint glow of radiation that fills the universe and is observed in the microwave portion of the electromagnetic spectrum. It is a crucial piece of evidence supporting the Big Bang theory and provides a snapshot of the universe when it was just 380,000 years old.