Lecture 6
Telescopes: optical, radio, X-ray
Friday July 11, 2008
The powerpoint for this class is available on Angel.
We also watched part of an educational DVD about Chandra. You may enjoy exploring the
websites of some of the great observatories, such as
Hubble,
Chandra, and
Spitzer.
Concepts:
- Refracting telescope: Uses a lens to focus light; suffers from chromatic aberration
- Reflecting telescope: Uses a mirror to focus light; requires highly reflective and smooth surface
- Interferometer: Group of telescopes that can combine data via interference pattern to act as one large telescope
- X-ray telescope: Nested shells of mirrors that reflect X-rays at grazing angles
Vocabulary:
- Sensitivity: How well faint details can be seen; better with larger telescopes (get more light)
- Resolution: How well close objects can be distinguished; better with larger telescopes (less diffraction)
- Active optics: Using a segmented primary to compensate for gravitational distortion of mirror while tracking
- Adaptive optics: Using a segmented secondary that is reshaped on very short timescales to reduce atmospheric blurring
Activity:
None
Random link:
Excerpt from news story titled "Astronomer rules out alien visits"
"Until recently, most detected planets have masses much larger than that of Earth, but new discoveries push that limit down to only a few Earth masses. Planets comparable to Earth should have solid surfaces and may harbour life.
"However, the distances between stars in our galaxy are enormous. Therefore, there is no way that life forms from another planet, if such exist, could have already visited us on Earth."
Updated July 11, 2008