Exam 1 Flashcards
Mars is a(n)
terrestrial planet.
The mean density of a planet is
its total mass divided by its volume.
The largest of the terrestrial planets is
Earth
The trans-Neptunian objects (such as Pluto, Sedna, Quaoar, etc.) are
small worlds of rock and ice, most of which orbit within the Kuiper belt.
Comets are typically
chunks of ice that begin to vaporize if they pass close to the Sun.
A general summary of the planets in the solar system is that
the planets are remarkably different in size, magnetic field strength, and magnetic field generation method.
The asteroid belt exists between the orbits of which planets?
Mars and Jupiter
The main characteristics of our solar system are
four small planets close to the Sun and four large planets far from the Sun.
A perfect circle is an ellipse with an eccentricity of
zero
Do all planets orbit the Sun in the same direction?
Yes. All planets orbit the sun the sun in the same direction, counter-clockwise.
Are the planetary orbits circular and if not, what are they?
Planetary orbits are not circular because plants orbit in an elliptical motion.
What are the characteristics of a terrestrial planet?
smaller, solid surfaces, low mass. High density (greater than rock)
What are the characteristics of a Jovian planet?
large, NOT solid, lower density, larger mass
a very slow conical motion of Earth’s axis of rotation
Precession
The nightly motion of objects across the sky is caused by the
rotation of Earth on its axis.
It is warmer in summer than winter because
the Sun is higher in the sky and the days are longer.
From the North Pole,
only half the celestial sphere can be seen on every clear night.
When the Sun is at one of the equinoxes,
day and night are of equal length everywhere on Earth.
In modern astronomy, the constellations are
88 regions of sky, covering the entire sky.
Declination
a measure of its position north or south of the celestial equator along a great circle passing through the north and south celestial poles.
The reason Earth experiences seasons is that
Earth’s rotation axis is not perpendicular to the ecliptic.
During a given night, some stars will be observed to pass through the
zenith.
When we watch the nighttime sky, we find that
most stars and constellations slowly rise in the east, pass overhead, and set in the west.
An apparent westward motion of a planet from night to night compared to the background stars (as viewed from Earth) is referred to as
retrograde motion.
Ptolemy’s model for the solar system was
Earth-centered, with epicyclic planetary orbits.
The early Copernican system for planetary motions is
Sun-centered, with planets moving in perfect circles around the Sun.
When Saturn is at its farthest distance from Earth, it is at
conjunction
The sidereal period of a planet is defined as the time between
two successive passages of the planet in front of a particular point in the sky (e.g., a star) as seen from the Sun.
Tycho Brahe
made accurate measurements of planetary positions, which Kepler later used to find the shapes of planetary orbits.
The eccentricity of a planet’s orbit describes
its shape compared to that of a circle.
Kepler’s second law states that a line joining a planet to the Sun
sweeps out equal areas in equal times.
Who was the first astronomer to use a telescope for viewing the sky?
Galileo
The Kepler model of the solar system is
Sun-centered, with elliptical planetary orbits.
When light passes through a prism of glass, the
different colors or wavelengths of light are separated in angle by the prism.
Visible Light
takes up only a very small part of the total range of wavelengths in the electromagnetic spectrum.
In terms of wavelengths, gamma rays are
shorter than X rays.
X rays and light are
the same thing except that X rays have a shorter wavelength than light.
The temperature scale most often used by scientists is the
Kelvin scale.
A perfect blackbody is so named because it
absorbs all radiation falling on it and reflects none.
A photon is a(n)
bundle of pure energy.
In comparing photons of different wavelengths, we find that the energy carried by a photon
is larger if the wavelength is shorter
According to the Doppler effect,
the wavelength of light is shifted to a shorter wavelength if the source of light is moving toward you.
The chemical makeup of a star’s surface is obtained by
spectroscopy of the light emitted by the star.
What has a higher angle of refraction in a prism: Light blue @ 500 nm or orange @ 600 nm?
Orange
How does the speed of light in glass compare to the speed of light in a vacuum?
The speed of light in glass is slower.
What is the refraction of light?
the change in direction of a light ray as it crosses from a less dense, transparent material to a more dense one
What is chromatic aberration in a telescope?
The light of different colors comes to a focus at different points inside the telescope.
Why was adaptive optics developed?
to compensate for image distortion caused by Earth’s atmosphere
One major difference between radio waves and light is that
radio waves have lower frequencies.
What is a charge-coupled device (CCD)?
an array of electronic sensors that record the charge buildup due to photon absorption
A radio telescope
is very similar to a reflecting optical telescope.
Which substance in Earth’s atmosphere is the main absorber of infrared radiation from space?
water vapor
The Very Large Array (VLA) built in New Mexico provides very sharp radio images of astronomical sources by combining the signals from many individual telescopes. It consists of
27 units.
