ASTR 111 UNIT 2

Seismic ___ waves cannot propagate through the Earth's core, while seismic _____ waves can.

Shear; Pressure

The theoretical resolution of a telescope in arc-seconds is given by

a = 2.5 x 10^-5 (lambda / D)

where lambda is the wavelength of the radiation in Angstroms and D is the diameter of the primary mirror or lens in meters. If we ________ the value of lambda while leaving D fixed, then the resolution angle a is ________

Double; Doubled

The theoretical resolution in arc-seconds for a radio telescope with a diameter D=10^4 meters observing at a wavelength of 10^8 angstroms is __________. This telescope would make observations with a resolution of _____ if it were located on the moon's surface, and observations with a resolution of ____ if it were located on the Earth's surface.

0.25 arc-seconds; 0.25 arc-seconds; 0.25 arc-seconds

The theoretical resolution in arc-seconds for an optical telescope with a diameter D = 5 meters observing at a wavelength of 10^4 Angstroms is ________. This telescope would make observations with a resolution of ________ if it were located on the Moon's surface, and observations with a resolution of ________ if it were located on the Earth's surface.

0.05 arc-seconds; 0.05 arc-seconds; 1 arc-second

Interferometry is the process that uses 2 or more small telescopes separated by a large distance to

improve the resolution to that of a telescope with a size equal to the distance between the telescopes

Atmospheric blurring is due to

turbulent motions in the Earth's atmosphere

If the concentration of CO2 in a planet's atmosphere increases,

the surface temperature increases because the additional CO2 acts like an extra blanket

A hot, dense gas at high pressure produces

a continuous spectrum

Atoms can be excited as a result of ______

collisions with other atoms AND absorption of radiation

The energy values for the electronic excitation levels in an atom are determined by

the number of protons in its nucleus

A hot, thin gas produces _____. Emission and absorption lines can be broadened due to ______.

emission lines; high temp and strong rotation

We know that according to the Doppler formula, the observed wavelength lambda_observed for a spectral line is related to the emitted wavelength lambda_emitted by the formula

(lambda_observed / lambda_emitted) = 1 + (v / c)

where c = 3 x 10^10 cm per second is the speed of light and v is the velocity of recession. If the emitted and observed wavelengths of the lines are given by

lambda_observed = 5,360 Angstroms, lambda_emitted = 4,102 Angstroms
lambda_observed = 5,672 Angstroms, lambda_emitted = 4,341 Angstroms
lambda_observed = 6,352 Angstroms, lambda_emitted = 4,861 Angstroms
lambda_observed = 8,576 Angstroms, lambda_emitted = 6,563 Angstroms
then the velocity v equals

away from us; 9.2 x 10^9 cm per second

The highest high tides occur when

the earth, moon, and sun form a line

The lowest high tides occur when

the earth, moon, and sun form a right triangle

Uranium 238 has a half life of about 4 billion years and decays into lead. How long will it take for 7/8 of the uranium to change into lead

12 billion years

If 2 planets with the same mass but diff temps start off with the same amount of hydrogen gas in their atmospheres, then the ___ planet will retain ___ of its hydrogen than the ____ planet.

cooler; more; hotter AND hotter; less; cooler

Radio Astronomy can be performed

all of the above; in poor weather, during the day, from the surface of the earth, at night.

X ray and gamma ray astronomy

can be performed only from space

Most of the oxygen in Earths current atmosphere was

created by plants

terrestrial planets

small, dense, rocky, with solid surfaces, clustered close to the Sun and each other, weak magnetic fields, slow rotation

jovian planets

large and gaseous, spread through outer solar system, strong magnetic fields, rapid roation

we do not detect shear waves on teh side of teh earth opposite from an earthquake. from this evidence we can deduce that

there is a liquid core in the earth

Consider 2 telescopes, one with a 3 in diameter and one with a 15 inch diameter. The 15 inch telescope recieves ____ times more light energy per second than the 3 inch telescope.

25

Detect Extra solar planets by

(i) Searches for periodic Doppler shifts of lines in the spectrum of the central star.

(ii) Searches for periodic changes in the pulsations observed from a pulsar

(iv) Searches for periodic drops in the light from the central star due to transits by a planet.

detect masses similar to earth by

(ii) Searches for periodic changes in the pulsations observed from a pulsar

(iv) Searches for periodic drops in the light from the central star due to transits by a planet.

When white light is passed through a cool, think gas, the photons absorbed

b) are re-emitted in the same direction they were originally moving in.

d) are re-emitted in random directions.

Most of the hydrogen in Earth's early atmosphere has

escaped into space

Most large telescopes are reflectors and not refractors becasue

a) large lenses are difficult to support.

b) large lenses are difficult to fabricate.

c) large lenses suffer from chromatic aberration.

Based on the best available evidence, the amount of CO2 in the Earth's atmosphere seems to be

increasing over the last 100 years, due to air pollution, destruction of rain forest, and ocean damage.

The ________ force causes hurricanes to spin ________ in the Northern hemisphere.

Corrolis, counterclockwise