chicka chicka

i just got an aspen guitar from a friend, but i'm don't know what model it is....does it say somewhere?

1) What is a common observational technique to obtain very deep images of the sky, i.e. an image capable to reveal very faint sources?

1. Replace film detectors with digital detectors

2. Use science-grade cameras

3. Obtain the average image from a large number of identical images of the same area of the sky

4. Obtain a color image

5. Use a science-grade flash

2) The Point Spread Function (PSF) of an imaging device (camera) is

1. The image that the device makes of an infinitely small source

2. The image that the device makes of an infinitely faint source

3. A measure of the distortions that the device introduces in the images it acquires

4. A measure of the sensitivity of the device to faint sources

5. A measure of the dynamic range of the device

3) Astronomers take images of celestial sources to

1. visualize the dark matter

2. study morphology, size and color distribution of sources

3. study the composition of the universe

4. measure the age of the universe

5. establish the chemical composition of the sources

4) An important factor that determines the final image quality of a ground-based telescope is

1. the polishing of the mirrors and lenses of the telescope

2. the noise of the detector

3. the dynamic range, or contrast, of the detector

4. the darkness of the sky at the observatory site

5. The blurring introduced by the atmosphere, or "atmospheric seeing"

5) Which of the following answers describes one of the reasons astronomers obtain spectra of celestial sources?

1. To measure the wavelength of light

2. To measure the color of the electromagnetic radiation

3. To measure the chemical content of the source

4. To measure the speed of light with the Doppler shift

5. To measure the speed of light with the cosmic expansion

thanks!

1) A spectral line that has a rest wavelength of 623.6 nm is observed from a galaxy at a wavelength of 623.8 nm. What velocity does the galaxy have (in units of km/sec)? Note that if the galaxy has a blueshift (moving toward us), its velocity should be written as a negative number.

2) If the universe is expanding at a constant rate, you can calculate the age from Hubble's constant. What would the age of the universe be if Hubble's constant were 90.0 km/sec per Mpc?

3) The measured temperature of the cosmic microwave background (CMB) is about 3 Kelvin, and the peak of this thermal radiation is seen at the wavelength of 1,000,000 nm. If the temperature of the last scattering surface of the CMB was 3,000 Kelven, then the peak of the emitted thermal radiation was at a wavelength of 1.0E+3 nm. What is the redshift of this scattering surface?

if you could help explain how to do any of them, it would be greatly appreciated, thanks!

The Milky Way galaxy has about 5e9 solar masses of gas in total. If 9 solar mass of that gas is turned into stars each year, how many more years could the Milky Way keep up with such a star formation rate?

______years

(The age of the universe is about 14 billion years, which can be written 1.4e10 years.)

thank you

From the perspective of an astronaut on a space craft traveling at 0.99c, her time seems to run normally, but the ________ to her destination would look only 1/7 as large.

The explanation for the twin paradox is that the astronauts aboard a spacecraft experience _________ as they first speed up their ship and then slow down at the star they visit.

thank you!

mines sierra leone by mt eden and foes (16 bit f*ck hoes remix) by borgore

:)

An emission or absorption line arise when the _______ in a hydrogen atom moves from one orbital to another with a different energy.

???

thank you!!

1. The extension of the Earth's meridian onto the celestial sphere.

2. The Sun's path as it moves through the constellations.

3. The extension of the Earth's equator onto the celestial sphere.

4. The extension of the Earth's orbital plane out to the celestial sphere.

north, south, east, west, or does it depend on your location?

a. the celestial pole

b. the celestial equator

c. the ecliptic

d. the zenith

e. the horizon

thank you!!

A. The sun will rise and set as usual

B. the sun will rise from the west and set in the east

C. the sun will stay at the same elevation over the day and sweep out a circle in the sky

D. the sun will remain at your zenith for the entire day

E. you will not see the sun. it is not above the horizon when viewed from the south pole in january

please help thank you!!

Suppose the universe is 14 billion light years in radius but only 8 billion years old, how big will the observable universe be in another billion years??

thanks!!

(compared to earth)

I have an assignment to find someone with a question about cancer, and research and answer it in 1-2 paragraphs. So it needs to be something that there IS an answer to..not like "Why haven't they found a cure?" ..

I will post the answer to the best question in a few days.. Thanks!

i'm trying to watch the movie Blow, but all the websites i've tried so far didn't work