Hubble Flashcards Preview

JJS Science > Hubble > Flashcards

Flashcards in Hubble Deck (34):
1

Advanced Camera for Surveys

The third-generation camera installed onboard HST during the 2002 space shuttle servicing mission.

2

asteroid

Member of a class of rocky objects orbiting the Sun, ranging in size from meters to hundreds of kilometers.

3

baryon

Member of a class of particles, including protons and neutrons, that make up most of the matter in the visible universe.

4

Big Bang universe

An evolving universe that had a singular origin in time.

5

black hole

A region of severely curved space around a collapsed stellar core where not even light can escape.

6

Cassegrain telescope

A telescope in which incoming starlight is reflected off a primary mirror to a secondary mirror that then refletects it back through a small central hole in the primary mirror to an eyepiece or instrument behind the primary.

7

Cepheid variable

A type of pulsating star with a period-luminosity relation that is useful in determining distances to the star's host galaxy.

8

comet

A kilometer-sized object of ice and rock that produces a visible tail of vapor and dust as it approaches the Sun during the course of its orbit.

9

cosmic microwave background radiation

The redshifted radiation from a very early time 380,000 years after the Big Bang when the expanding universe transitioned from its hot, dense, bright origin to a cooler, transparent state.

10

dark energy

The mysterious energy driving the observed acceleration in the expansion of the universe.

11

dark matter

The dominant, unknown constituent of matter in the universe that interacts with visible matter gravitationally but not through electromagnetic forces.

12

Doppler effect

The wavelength shift in the spectrum of a light source as that source moves toward or away from an observer.

13

Einstein ring

The simplest case of a gravitational lens, in which the observer, lens, and background object are perfectly aligned.

14

electromagnetic radiation

Commonly referred to as llights at optical wavelengths, this radiation is due to oscillating electric and magnetic fields.

15

elliptical galaxy

A gas-poor, elliptically shaped system of up to 500 billion typically old stars.

16

emission nebula

A glowing cloud of interstellar gas heated by the ultraviolet light of a nearby hot star.

17

exoplanet

A planet outside the solar system.

18

globular star cluster

A densely packed, spherical cluster of up to a million old stars typically found in the halos of galaxies.

19

gravitational lens

An object or cluster whose mass is large enough to curve the surrounding space to a degree at which distortions are produced in the images of background objects.

20

Hertzsprung-Russell diagram

A diagram comparing the temperatures and luminosities of stars that is useful in charting their evolution over time.

21

Hubble's constant

The constant of proportionality between the redshift velocities of galaxies and their distances.

22

Hubble's law

The linear relationship between the redshift velocities of galaxies and their distances that is indicative of an expanding universe.

23

interstellar dust

Submicron-sized interstellar particles of carbon, oxygen, and silicon compounds that are effective in attenuating background starlight.

24

interstellar molecular cloud

An interstellar cloud of gas and dust that is dense enough to form molecules and block the optical light of background stars.

25

light-year

The distance 6 trillion miles that light travels in one year.

26

main sequence star

A star that is powered by the nuclear fusion of hydrogen into helium in its core.

27

Near-Earth Object

A nearby asteroid whose orbit intersects that of Earth.

28

neutrino

An elementary particle of very low mass produced in nuclear reactions, such as those in the solar core and Type II supernovae.

29

neutron star

The collapsed core remnant of a Type II supernova; it typically has a mass of about 1.5 solar masses within its radius of 10 kilometers.

30

photon

The particle that carries electromagnetic radiation with wavelike characteristics.

31

planetary nebula

The short-lived nebula, lasting for about 50,000 years, that results when a dying red giant blows off the gaseous layers surrounding its core.

32

pulsar

A rapidly rotating neutron star.

33

red giant

After a solar-type main-sequence star fuses all of its core hydrogen into helium, it evolves into this type of cooler, larger, more luminous star.

34

resolving power

A measure of the smallest angular separation that a telescope can resolve in an image.