1. Optical Telescopes, Radio Telescopes and Other Technologies Advance Our Understanding of Space
Unit E: Topic Three

2. 3.1 Using Technology to See the Visible

3. Using Technology to See the Visible
In this section, we’ll look at a number of different telescope. Each provide us with a variety of information about the objects that make up our universe.
Amazing History of the Telescope (to 2:22 min)

4. Telescopes
Hans Lippershey made one of the first telescopes, but Galileo has been credited for first using it to study the night sky.

5. Optical Telescopes Think of them as “light collectors”
Purpose: To gather and focus the light from stars so that we can see them.
Used to magnify objects at great distances.
Has an objective lens and an ocular lens (eyepiece).
Resolving Power: The fineness of detail a telescope can produce. Depends on the diameter of the objective lens.
There are two types of optical telescopes.

6. 1. Refracting Telescope Use two lenses to gather and focus starlight
Light comes in parallel
Lenses bend the light
Benefit: They give much better images than equal size reflectors.

7. 2. Reflecting Telescope
Uses mirrors instead of lenses to gather and focus the light from the stars.
Were created by Isaac Newton to fix the problems that refracting telescopes had with focusing colours.
Benefit: Reflectors can be made much larger than refractors.

8. Combination Telescope

9. The Trouble with Earth-based Telescopes
Although remote mountains make excellent sites for building and operating telescopes away from light pollution and air pollution, astronomers are still at the mercy of the weather.
Clouds, humidity, moisture and winds in the atmosphere can interfere with star-gazing.

10. The Hubble Space Telescope
To escape these problems, the Hubble Space Telescope was built.
It orbits earth in 95 minutes
It is a reflecting telescope, using mirrors to focus light from extremely distant objects.
It has been used to discover galaxies in parts of space where Earth-based telescopes see nothing but blackness.

11. See more Images
Hubble Images Advent calendar

12. Space Fact of the Day!
Hubble’s eight-foot light-collecting mirror had to be polished continuously for a year to an accuracy of 10 nanometers, about 1/10,000 the width of a human hair.
Unfortunately, the contractors polished the mirror precisely wrong, off by a painful 2,200 nanometers.
Since the problem was fixed in 1993 by installing corrective lenses, Hubble has become the source of roughly 25 percent of all published astronomy research papers.

13. Interferometry: Combining Telescopes for Greater Power
Interferometry: Technique of combining telescopes to improve resolution (clarity of details).
The twin Keck Observatory telescopes are the world’s most scientifically productive optical and infrared telescopes. Each telescope weighs 300 tons and operates with nanometer precision. The telescopes’ primary mirrors are 10-meters in diameter and are each composed of 36 hexagonal segments that work in concert as a single piece of reflective glass.

15. Mauna Kea Observatory
There are currently thirteen working telescopes near the summit of Mauna Kea.
Nine of them are for optical and infrared astronomy.
Three of them are for submillimeter wavelength astronomy.
One is for radio astronomy.
They include the largest optical/infrared  telescopes in the world (the Keck telescopes), the largest dedicated infrared telescope (UKIRT) and the largest submillimeter telescope in the world (the JCMT). The westernmost antenna of the Very Long Baseline Array (VLBA) is situated at a lower altitude two miles from the summit.

16. Electromagnetic Spectrum

17. Why Mauna Kea? Mauna Kea is unique as an astronomical observing site.
The atmosphere above the mountain is extremely dry -- which is important in measuring infrared and submillimeter radiation from celestial sources.
It is cloud-free, so that the proportion of clear nights is among the highest in the world.
Its distance from city lights and a strong island-wide lighting ordinance ensure an extremely dark sky, allowing observation of the faintest galaxies that lie at the very edge of the observable Universe.

18. Mauna Kea TMT
Proposed joint project by the US, Canada, Japan, China, and India to build a thirty-meter telescope (TMT) on Mauna Kea in Hawaii.
Would make images with spatial resolution 12 times sharper than the Hubble Space Telescope.
However, there are a number of people opposing its construction. Why?

19. Mauna Kea TMT

20. Controversy
The proposed construction of the TMT on Mauna Kea sparked protests and demonstrations across the state of Hawaii.
Mauna Kea is the most sacred mountain in Hawaiian culture.
The mountain is also conservation land held in trust by the state of Hawaii to protect endangered animals.
Protests began locally within the state of Hawaii on October 7, 2014 but went global within weeks.
While opposition against the observatories on Mauna Kea has been ongoing since the first telescope this protest may be the most vocal.

21. Over the years, the opposition to the observatories may have become the most visible example of the conflict science has encountered over access and use of environmental and culturally significant sites.

22. Written response
How important is Science? Does it outweigh cultural and environmental concerns?

23. Written Response
Briefly describe one type of telescope and one advantage of using it. (2-4 sentences)
Optical Telescopes
Refracting Telescopes
Reflector Telescopes
Combination Telescopes
Space Telescopes

24. 3.1 Review Questions Why is there need for telescopes?
What type of optical telescope uses mirrors?
Describe the technique of interferometry.
The resolving power of a telescope is a measure of its
Operating ability under poor conditions
Magnification
Ability to distinguish details in an object
Quality in general
Why is the Hubble Space Telescope a reflector and not a refractor?
Imagine you had to construct an observatory on Earth for a ground-based reflecting telescope. Describe where the ideal location would be and why.
When finished – work on the “Early Contributions” worksheet and add any new words to your Space Dictionary.