Download Topic 5 Assignment - Science 9 Portfolio

Science 9
Unit 5: Space
Name:
Topic 5 - What Channel Is This?
Radio Telescopes
Radio waves are received from stars, galaxies, nebulae, the Sun and even some
planets. With the development of radio telescopes, astronomers gain an
advantage over optical telescopes, because they are not affected by weather,
clouds, atmosphere or pollution and can be detected day or night. Much
information has been gained about the composition and distribution of matter in
space, namely neutral hydrogen, which makes up a large proportion of matter in
our Milky Way galaxy. Radio telescopes are made of metal mesh and resemble a
satellite dish, but are much larger, curved inward and have a receiver in the
center.
Radio telescope in Arecibo, Puerto Rico.
In 1932 Karl Jansky built a radio antenna that was able to identify radio waves
from space. Grote Reber built a radio dish based on Jansky’s antenna findings,
where he ‘listened’ to the sky during the 1930’s. He discovered that the strongest
radio waves came from specific places in space. The static Rober heard became
louder when he tuned into these radio objects. The loudest being our Sun in the
Milky Way Galaxy.
Bigger Radio Telescopes
Radio waves have wavelengths that are millions of times longer than light waves,
meaning that these waves give less resolution, but can penetrate dust clouds in
the galaxy, where light waves cannot.
Seeing Radio Waves
Radio telescope waves provide data, which astronomers graph, using computers
to store the data and false color it to produce images of the radio waves, which
are coded to the strength of the waves. Blues for low intensity, and as the signal
gets stronger the colors go through greens, yellows, reds and whites. Radio
observations have provided a whole new outlook on objects we already knew,
such as galaxies, while revealing pulsars and quasars that had been completely
unexpected.
Optical Connections
Radio astronomers wanted to connect their radio waves with visual data obtained
from optical telescopes. Until the resolution of radio telescopes improved making
the connection was difficult. It is now common.
Connecting Radio Telescopes
By combining several small radio telescopes ( just like they do with optical
telescopes ) greater resolving power can be achieved. This is referred to as
radio interferometry, improving the accuracy and performance of the image in
making radio maps. The greater the distance between the radio telescopes the
more accurately they can measure position.
Arrays, like the Very Large Array in Sorocco, New Mexico, which uses 27
telescopes arranged in a Y, can improve accuracy even more.
Radio Telescopes Bigger Than Earth
Telescopes can now be connected without wires, thanks to computers and
clocks. This method is called Very Long Base Interferometry ( VLBI ). With this
technique, images 100 times that of the largest optical telescope can be
captured. This is done by capturing images from any or all radio telescopes in the
world. Imagine a telescope as large as the Earth itself.
Topic 5 Assignment
Vocabulary: (Define in detail each of the words)
Electromagnetic radiation- a kind of radiation including visible light, radio waves,
gamma rays, and X-rays, in which electric and magnetic fields vary
simultaneously.
Radio astronomy- the branch of astronomy concerned with radio emissions from
celestial objects.
Radio objects- devices which use radio waves to determine things at large
distances.
Interferometry- an instrument in which wave interference is employed to make
precise measurements of length of displacement in terms of the wavelength.
1. How do astronomers use radio waves to learn about the composition of
stars?
They use radio telescopes which send back radio waves, including shapes and
sizes and info on other planets and stars.
2. Who is Karl Janksy, and why are his contributions important to space
exploration?
Karl Jansky was an American physicist and radio engineer who in August
1931 first discovered radio waves emanating from the Milky Way. He is
considered one of the founding figures of radio astronomy.
3. Draw the following on an electromagnetic spectrum below.
(a)
(b)
(c)
(d)
(e)
(f)
(f)
microwaves
infrared radiation
Xrays
ultraviolet radiation
radio waves
gamma rays
(c)
(d)
(b)
(a)
(e)