Space science set 2 Flashcards
What is radio astronomy?
Radio astronomy is a sub-field of astronomy that studies space (celestial objects) using radio frequencies
Instead of using visible light, what does radio astronomy measure?
Radio astronomy measures the radio waves of celestial objects.
How were radio waves discovered?
Radio waves were discovered by accident by Karl Jansky in 1931.
What was Karl Jansky doing that he happened upon radio waves?
Jansky was trying to figure out the static noise that was interfering with radio telephone services.
What did Jansky discover?
Jansky discovered a sound that reoccurred every 23 hours and 56 minutes.
Why was the timing of the sound important?
The time of 23 hours and 56 minutes is the time it takes for the earth to rotate
What is a sidereal day?
The sidereal day is the time it takes for an object to come back to the same location after one rotation of the earth
What realization did Jansky come to because of the strange timing?
He realized that the sound was not from earth.
where was the sound coming from?
The sound was coming from the Milky Way, around Sagittarius constallation.
What is an astronomical map?
An astronomical map is a map of the star systems… where celestial objects are in the sky
What did Grote Reber do?
Grote Reber built the first dish-shaped radio telescope in his back yard in 1937
Why do radio telescopes need to come in different shapes and sizes?
Radio telescopes need to be in different shapes and sizes because radio waves range from 3m to 30 m
How has technology improved radio telescopes?
Technology has meant that the telescopes can be networked together to act as one huge telescope
What is interferometry?
Interferometry is when they network (join with wires and computers) a bunch of radio telescopes so they act like one giant dish
Where is the VLA Very Large Aray?
The VLA is in New Mexico, and it has 27 25 m diameter radio antennas set in a y formation
How does a radio telescope work?
the dish is a concave shaped (parabolic) reflector that takes the incoming radio waves and brings them into focus (like a mirror reflecting telescope)
What shape is a radio telescope?
A radio telescope is concave
What is the Cassegrain design?
Cassegrain design uses a secondary reflector (like a 2nd mirror) and a feed horn to bring the radio waves into sharp focus.
What is at the feed horn?
An antenna is at the feed horn
What does the antenna do?
An antenna converts the radio waves into an electric current
How do they stop random interference from affecting the current?
They cool the telescope with liquid nitrogen or liquid helium to stop any random signals.
What are random signals called?
Noise
Why do they want less noise?
The clearer the signal, the less noise there is, the easier it is to pick up very weak signals from space
What does the tuner do?
The tuner allows the astronomer to focus in on a single radio signal from the thousands that come into the antenna
What is an amplifier?
An amplifier increases the strength of the weak electrical current caused by the radio signals
Why do they need it to be hooked up to a computer?
The computer System records and stores all the electric signals, helps them analyze data and controls the telescope’s movement
What is SETI?
SETI is the Search for Extraterrestrial Intelligence (Aliens)
What are people in SETI doing?
SETI scientists are looking for life in other places in the universe.
How do they think they might find life on other planets?
They think that other planets might be sending out electrical signals as well
How might they tell if it is a life form’s signal?
They think that a signal from other life forms would be artificially produced and could be separated from the universe’s background noise.
How is human made radio different than nature’s radio?
Human radio waves are in a narrow band, ie they are in a narrow band of the electromagnetic spectrum – like tuning into a radio staion
what might an alien signal do?
They think an alien signal will be repeated, so they search the narrow bands looking for repeating sounds
What will a repeated signal show?
A repeating signal will prove there is life in other places
When did we send a message to space?
In 1974, November we sent a message to space.
To what location in space did we send the message?
We sent the message to the M12 star cluster, 21 000 light years away
Where was the space message sent from
The space message was sent from the Arecibo radio telescope in Puerto Rico
What was the space message we sent?
The message was 1679 binary numbers ( 0s and 1s), if organized into a 23 column by 73 row run-length coding image told them information about us, our DNA, a human picture, a solar system map, and a picture of a telescope that sent the image
When should we expect a response if they got it on M12?
It will take 42 000 years to get the reply
Where on the electromagnetic spectrum would a smart alien send a signal?
On the 1-10 Ghz level there is little noise, so this would be the best channel
Where are SETI building their own radio telecope?
At the SETI institute at the University of Berkeley in California they are building their own alien finding telescope
Who was the first person to think he heard some alien noise?
In 1899 Nikola Tesla heard some unexplained signals on his Tesla coil. He thought it was from Mars.
What did Marconi and Kelvin believe?
Marconi and Kelvin both believed we could use radio signals to communicate with beings on Mars.
What weird thing happened in 1924?
In 1924 Mars passed very close to earth so for 5 minutes every hour they had radio silence and listened for signals from Mars.
Who was there to decipher messages?
Cryptographers were they at the ready to decipher messages from Mars
Why do SETI researchers dream of that time?
Nowadays they have to filter out so much human radio noise, it is very difficult
When did modern SETI begin?
Modern SETI began in 1960 with Project Ozma
Who was project Ozma named after?
The wizard of Oz was the namesake for project ozma
What did Frank Drake do with his Project Ozma?
He pointed two radio telescopes at two nearby stars for four months at 1.4 Ghz looking for signals from aliens. This inspired government to fund research like this
How can you participate in SETI?
Go to SETI@Home and they can use your computer to help them search the data from the radio signals from space!!
What do microwave telescopes do?
Microwave telescopes give insight into the radiation field that is around the universe
What is the Big Bang?
The Big Bang is what scientists think started the universe.
What are infrared telescopes good at doing?
Infrared telescopes peer through the dust of the universe that blocks visible light.
What do ultraviolet telescopes do?
Ultraviolet telescopes can see into the chemical composition of the galaxy and helps to see changes over time.
Although our atmosphere protects us from harmful rays, how does it hinder astronomers?
Our atmosphere can absorb some wavelengths of light and distort images.
What is the Hubble Space Telescope?
The Hubble Space Telescope was launched into space to get past the atmosphere and has been peering into space for over 20 years.
What does the Chandra X-Ray telescope observe?
The Chandra X-ray telescope measure xrays from space!
What will be launched into space in 2018?
In 2018 the James Webb space telescope will be launched into space to work outside the atmosphere
What is the Kuiper Airborne Observatory and the SOFIA Stratospheric Observatory for Infrared Astronomy?
They are both observatories that are built onto aircraft, and take measurements 12 km up into the sky where there is less water vapor.
What does water vapour absorb?
water vapour absorbs infrared radiation
What are strata-scopes and BLASTs
They are telescopes on high altitude balloons (1950s to 1970s) BLASTS are Balloon-borne Large Aperture Sub-millimeter Telescopes (2005-2010)
What is the largest telescope to leave the ground to date?
The Sunrise telescope looks at our sun.It goes in the arctic summer and goes up on balloons.
What is the purpose of all telescopes?
All telescopes tell us more about our universe.
