Astrophysics: Star Systems and Galaxies

High frequency corresponds to high energy and low wavelength.

Radio waves can penetrate clouds and can be detected at any time of day or night.

The celestial sphere is an imaginary sphere where all visible celestial objects are projected.

<p>Earth's rotation makes celestial objects appear to move across the sky from east to west.</p> Signup and view all the answers

<p>Earth's rotation and its revolution around the Sun affect the night sky's appearance.</p> Signup and view all the answers

<p>A light-year is a measure of distance, defined as the distance light travels in one year.</p> Signup and view all the answers

<p>Parallax causes apparent shifts in the positions of nearby celestial objects due to Earth's motion.</p> Signup and view all the answers

<p>Triangulation is used to measure distances to stars by observing them from different positions.</p> Signup and view all the answers

<p>Telescopes gather and focus light from distant objects, enabling detailed observations and the detection of electromagnetic radiation beyond the visible spectrum.</p> Signup and view all the answers

<p>Ultraviolet telescopes are placed in space because Earth's atmosphere absorbs most ultraviolet radiation.</p> Signup and view all the answers

<p>The two main types are optical telescopes, which detect visible light, and radio telescopes, which focus on radio waves.</p> Signup and view all the answers

<p>Gravity acts as an attractive force that pulls objects with mass towards one another, with more massive objects exerting a greater pull.</p> Signup and view all the answers

<p>The celestial sphere serves as an imaginary framework to model the positions and motions of celestial objects as they appear in the night sky.</p> Signup and view all the answers

<p>Spectroscopy analyzes light from stars and galaxies to determine their composition, temperature, speed, and identify specific elements.</p> Signup and view all the answers

<p>Earth's rotation causes celestial objects to appear to move across the sky from east to west.</p> Signup and view all the answers

<p>Astronomers assess the proportion of older, redder stars versus younger, bluer stars to infer the age of galaxies.</p> Signup and view all the answers

<p>A standard candle is an astronomical object with a known luminosity that allows for accurate distance measurements based on its brightness.</p> Signup and view all the answers

<p>The two types of motion are Earth's rotation and revolution around the Sun.</p> Signup and view all the answers

<p>Parallax provides the angle of apparent shift in a star's position as observed from different points on Earth, enabling distance calculation through triangulation.</p> Signup and view all the answers

<p>A spiral galaxy has distinct spiral arms where new stars are forming, while an elliptical galaxy has a more rounded shape with older stars.</p> Signup and view all the answers

<p>A light-year is the distance light travels in one year, and it is a crucial unit for measuring astronomical distances.</p> Signup and view all the answers

<p>Astronomers observe the star's position from two different locations on Earth over six months and calculate the parallax angle based on these observations.</p> Signup and view all the answers

<p>The longer the baseline distance, the greater the observed parallax angle, indicating the star is closer.</p> Signup and view all the answers

<p>The Cosmological Principle asserts that the universe is homogeneous and isotropic on large scales, implying there is no center or special location in the universe.</p> Signup and view all the answers

<p>Redshift indicates that distant galaxies are moving away from us, providing evidence for the expansion of the universe as predicted by the Big Bang Theory.</p> Signup and view all the answers

<p>Beyond 100 parsecs, astronomers rely on redshift and other methods, as parallax measurements become increasingly difficult due to smaller angles.</p> Signup and view all the answers

<p>CMB is the afterglow radiation from the Big Bang, which fills the universe and provides critical evidence for the Big Bang Theory.</p> Signup and view all the answers

<p>The expansion causes distant galaxies to move away from us at higher speeds, making them appear farther than they are.</p> Signup and view all the answers

<p>Redshift helps astronomers track the movement of stars and galaxies by indicating how much their emitted spectrum has shifted towards the red end.</p> Signup and view all the answers

<p>Parallax allows visualization through apparent shifts in a star's position against a background as observed from different points, demonstrating how distance affects view.</p> Signup and view all the answers

<p>An elliptical galaxy has a smooth, rounded shape and lacks spiral arms, typically containing older, redder stars, unlike spiral galaxies which have distinct arms and often younger stars.</p> Signup and view all the answers

<p>The main sequence is the longest stage because a star remains stable, primarily fusing hydrogen into helium, which allows it to maintain balance against gravitational collapse.</p> Signup and view all the answers

<p>When a star runs out of hydrogen fuel, it collapses under gravity, leading to a significant increase in temperature and size, transforming it into a red giant.</p> Signup and view all the answers

<p>A white dwarf forms when a red giant expels its outer layers, creating a planetary nebula, while the remaining core collapses into a dense star known as a white dwarf.</p> Signup and view all the answers

<p>During a supernova, a massive star explosively ends its life, releasing vast energy, producing heavy elements, and potentially leaving behind a neutron star or black hole.</p> Signup and view all the answers

<p>More massive stars have shorter lifespans because they consume their nuclear fuel at a much faster rate due to higher core densities.</p> Signup and view all the answers

<p>White dwarfs are located in the lower left portion of the Hertzsprung-Russell diagram, indicating their low luminosity and high temperature compared to other star types.</p> Signup and view all the answers

<p>Astronomers use trigonometry by measuring angles between a distant star and two points on a baseline, with greater baselines yielding more noticeable parallax.</p> Signup and view all the answers

<p>Parallax measurements are based on observing the apparent shift of a star against background stars as Earth orbits the Sun. The greater the observed shift, the closer the star is to Earth.</p> Signup and view all the answers

<p>The accuracy of parallax measurements decreases significantly for stars that are farther away, making it extremely difficult to measure distances beyond a certain limit.</p> Signup and view all the answers

<p>Standard candles are astronomical objects with known luminosities that allow astronomers to determine their distances based on their observed brightness. They are crucial for measuring distances to galaxies too far for parallax methods.</p> Signup and view all the answers

<p>The size of the observable universe is limited by the age of the universe, as it determines the distance light has traveled since the Big Bang. Objects can only be seen if their light has had enough time to reach us.</p> Signup and view all the answers

<p>When a light source moves towards an observer, the wavelength is compressed, causing a blueshift; conversely, if it moves away, the wavelength is stretched, resulting in a redshift.</p> Signup and view all the answers

<p>The Cosmic Microwave Background Radiation is considered evidence for the Big Bang as it represents the faint afterglow and is consistent with predictions of a uniformly expanding universe.</p> Signup and view all the answers

<p>Astronomers analyze the light from distant galaxies, detecting shifts in wavelength that indicate whether they are moving towards or away from us, which confirms the universe's expansion.</p> Signup and view all the answers

<p>The two main types of standard candles are Cepheid variable stars and Type Ia supernovae.</p> Signup and view all the answers