Astronomy Exam 2

electromagnetic radiation

an electric and magnetic disturbance that transports energy at the speed of light c

wavelength (λ)

the distance between the peaks of a wave

nanometers

Nanometers are a unit of measurement equal to one billionth of a meter, used to measure wavelengths of light

Frequency (v)

the number of waves that pass a stationary point in 1 second

photon

packet of light waves that can act as a particle or as a wave. The energy carried by a photon is proportional to its frequency and inversely proportional to its wavelength.

spectrum

display of light that is viewed or recorded after being sorted in order of wavelength or frequency

complete electromagnetic spectrum

gamma-rays, X-rays, ultraviolet (UV) radiation at the higher frequencies, and infrared (IR) radiation, microwaves, and radio waves at the lower frequencies

atmospheric windows

specific wavelength ranges in the electromagnetic spectrum where Earth's atmosphere allows certain types of radiation, like visible light and radio waves, to pass through with minimal absorption.

Refracting telescopes

Use a primary lens to bend and focus light onto an image

Reflecting telescopes

Easier to build than refracting/ use a primary mirror to focus the light. Is not affected by chromatic aberration

eyepiece

Magnifies the image produced by the telescope’s primary lens or mirror

focal lengths

The distance between the lens and the image sensor when the subject is in focus.

chromatic aberration

causes refracting telescopes to not bring all colors to the same focus, resulting in color fringes around the images

achromatic lens

corrects for chromatic aberration

optical telescopes

reflecting telescopes:

use lenses or mirrors to gather and focus light from distant objects

radio telescopes

reflecting telescopes:

are astronomical instruments that detect radio waves from space.

light-gathering power

The telescopes ability to collect light, most important feature

Resolving power

the ability of a telescope to reveal fine detail and is expressed by the equation

Diffraction fringes

caused by the interaction of light waves with the telescope’s apertures, limit the amount of detail that can be seen

Magnifying power

the ability of a telescope to make an object look bigger, least important

Mountains for observatories

The air on top of a mountain is relatively steady, and the seeing is better

Observatories are located far from cities to avoid light pollution

reflecting telescope focuses

light first comes to a focus at the prime focus, but a secondary mirror can direct light to other locations such as the Cassegrain focus. The Newtonian focus and Schmidt-Cassegrain focus are other focus locations used in some smaller telescopes

sidereal drive

Because Earth rotates, telescopes must have this to stay pointed at celestial objects

Spectrographs

using prisms or a grating spread light out according to wavelength to form a spectrum, revealing hundreds of spectral lines produced by atoms and molecules in the object being studied

comparison spectrum

contains lines of known wavelengths allows astronomers to measure the precise wavelengths of individual spectral lines produced by an astronomical object

Cosmic rays

are not electromagnetic radiation; they are subatomic particles such as electrons and protons traveling at nearly the speed of light, arriving from mostly unknown cosmic sources

Atom

Contains a nucleus surrounded by a cloud of electrons

nucleus

made up of one or more positively charged protons and, except for hydrogen, uncharged neutrons

isotopes

Atoms of the same element (that is, having the same number of protons) with different numbers of neutrons

ion

an atom that has lost or gained an electron through ionization

Coulomb force

The force that allows electrons in an atom are attracted to the nucleus

excited atom

an electron is raised to a higher orbit by a collision between atoms or the absorption of a photon having the proper energy

thermal energy

The sum of the agitation of the particles in an object, heat is the flow

blackbody radiation

Collisions among the particles in a hot, dense object accelerate electrons and cause the emission of this

Stefan-Boltzmann law

states that the hotter an object, the more total energy the blackbody radiates

Wien’s law

quantifies the relationship between a blackbody’s temperature and the wavelength of maximum intensity

Kirchhoff’s 1st law

a hot solid, liquid, or dense gas emits electromagnetic radiation at all wavelengths and produces a continuous spectrum

Kirchhoff’s 2nd law

an excited, low-density gas produces an emission spectrum containing emission lines

Kirchhoff’s 3rd law

a light source viewed through a low-density, cool gas produces an absorption spectrum containing absorption lines

Doppler effect

The change in wavelength of radiation- red receding, blue moving towards

Balmer series

Spectral lines in the visible and near-ultraviolet spectrum of hydrogen produced by transitions whose lowest orbit is the second.

Radial velocity

the part of its velocity directed toward or away from Earth, what the doppler effect reveals

granulation

The fine structure visible on the solar surface caused by rising currents of hot gas and sinking currents of cool gas below the surface.

helioseismology

The study of the interior of the Sun by the analysis of its modes of vibration.

magnetic carpet

The widely distributed, low-level magnetic field extending up through the Sun’s visible surface

Maunder butterfly diagram

A graph showing the latitude of sunspots versus time; first plotted by W. W. Maunder in 1904.

solar constant

A measure of the energy output of the Sun; the total solar energy striking 1 m2 just above Earth’s atmosphere in 1 second.

proton–proton chain

A series of three nuclear reactions that build a helium atom by adding together protons; the main energy source in the Sun.

neutrino

A neutral, massless atomic particle that travels at or nearly at the speed of light.

Photosphere

the innermost layer of the Sun's atmosphere, emitting visible light. It is the region where energy is transferred from the Sun's core to the outer atmosphere