1. Topic 4 Space Exploration
Bigger and Smarter Telescopes
Topic 4
Space Exploration

2. New Discoveries Sir William Herschel:
In 1773 Sir William Herschel (an English astronomer) built one of the first really large reflecting telescopes and used it to discover Uranus
His discovery of Uranus was exciting because it proved the existence of other planets in the solar system

3. New Discoveries Gerard Kuiper:
Discovered methane gas in Saturn’s moon (the moon Titan) and two new moons of Uranus
He made these discoveries with the world’s largest refracting telescope (101 cm) in the world (at that time) which was found at the Yerkes observatory near Chicago.

4. Combining Telescopes
Now our telescopes are so advanced that computer programs can combine images from two or more telescopes to create very detailed images of very distant objects.

5. Combining Telescopes
The twin Keck telescope has a resolving power that can allow it to distinguish each headlight on a car from 800 km away!

6. Combining Telescopes
Spitzer Space Telescope: The Musical

7. Adaptive Optics Adaptive Optics:
Technology that adjusts the mirror of a telescope, or adjusts the image of a telescope., to cancel the effects of the constant changes in Earth’s atmosphere

8. Adaptive Optics
Stars twinkle because the motion of Earth’s atmosphere refracts their light randomly and this makes it difficult for astronomers to get a clear view
New Technology Telescope in La Silla, Chile

9. Adaptive Optics
In order to solve this problem computers are put into giant reflecting telescopes under the mirrors
The computer makes small changes to the mirrors in order to account for the moving atmosphere and allows for much more detailed images of celestial objects

10. Adaptive Optics
Progress in Telescopic Astronomy
Keck Telescope

11. Distance to the Stars
Many astronomers (and regular people) often ask questions such as:
Where are stars?
How far away are these stars from Earth?
How big is the universe?

12. Measuring With Triangulation
Triangulation / Parallax Technique:
A method of measuring distance indirectly by creating an imaginary triangle between an observer and an object whose distance is to be estimated.

13. Steps of Triangulating
Create a Baseline:
The distance between two observers is measured
Object of Interest
Measure Distance A
Baseline B
Observers

14. Steps of Triangulating
Measure the angles from the end of the Baseline:
Both observers will look at the object of interest and find the angle between the object and the baseline A B
Measure Angles

15. Steps of Triangulating
Make a scale drawing of the imaginary triangle.
A triangle is drawn to scale and the distance to the object is discovered through trigonometry
Scale Example:
1 km = 1 cm A B
Measure the Various Distances to the Object

16. Triangulating on a Star
Find the longest baseline possible:
The longest baseline on Earth is its diameter
In order to use this baseline, a star is viewed twice over a six month period
This gives a baseline that is the Earth’s diameter

17. Triangulating on a Star
Use Parallax to find reference points:
As the Earth moves around the sun the star will appear to move against the background of other stars

18. Triangulating on a Star
Measure the angles of the imaginary triangle:
Parallax allows the observer to measure the angles of the triangle

19. Triangulating on a Star
Discover the distance to the star:
The angles of the triangle allow for the discovery of the distance of the star from Earth.

20. Large Enough Units: AU and Light-Years
The nearest star to Earth is Proxima Centauri and it lies more than Astronomical Units (AU) from the Sun
Astronomical Units (AU):
The distance from Earth to the Sun
1 AU = km

21. Large Enough Units: AU and Light-Years
Astronomical Units are good to use when looking at the solar system, however since the Universe is so large, Astronomical Units become impractical
Instead, Astronomers use Light-Years to measure distances in the Universe

22. Large Enough Units: AU and Light-Years
The distance that light travels in one year
1 Light-Year = AU = 9.5 trillion km (ie km!!!!!)

23. Large Enough Units: AU and Light-Years
***Note:
Proxima Centauri is
4.28 Light-Years /
AU /
40,800,000,000,000 km away from Earth