Chapter 5: Geometry of the Solar System Flashcards
How do camera shop owners get rich from people’s passing interest in astronomy? What can you buy instead that is just as good and cheaper?
by touting the great properties of small telescopes - they are actually a pain to use and not much better than binoculars.
You can use binoculars and clamp to connect them to a tripod, which is much cheaper
What is the use of an optical telescope?
optical telescope gathers light and allows you to examine an image at a focal point
Why do even the best optics have a limited resolution in telescopes?
How does the atmosphere affect the image? Why do stars twinkle?
because of the wave nature of light
ie. water waves bend when they strike the edge of a barrier - light waves do the same
the twinkling of stars comes from the turbulence in the air that makes up the atmosphere – the atmosphere basically acts as a huge distorting lens.
What are the 2 basic type of astronomical telescopes
- refractors
- reflectors
What are refractors vs reflectors
refractors collect light. by means of a glass lens (or combination of lenses)
reflectors colect light with a curved mirror
What is the aperature of a telescope determined by ?
aperature of any telescope is determined by the diameter of the glass lens or mirror
How is the magnification done in any telescope?
done by a smaller lens known as an eyepiece or ocular
What allows a higher magnification to be used in a telescope?
larger aperatures (larger diameter of the gass or mirror) because more light can be collected and therefore a higher magnification can be used
What are the 2 largest telescopes in the world?
the two Keck telescopes mounted on Mauna Kea, Hawaii
What discovery determined that stars other than the sun have planets (where, which telescope, when, what did they observe)
It was the Keck observatory in 1999 that observed the transit of a massive planet in front of it’s star 153 light years away - confirming or the first time that stars other than the Sun have planets
Describe what is depicted in this image
This is a refractor telescope.
the primary lens is a convex spherical lens which collects and concentrates the light - parallel light rays from the star are concentrated onto a smaller area called the eyepiece
the eyepiece is a concave lens which makes th concentrades light rays parallel again
the focal point is behind the eyepiece
Describe what is depicted in this image
this is a reflector telescope
the light from a celestial body bounces off a primary (objective) mirror onto a secondary mirror, which reflects the light into the eyepiece.
What instruments does Canada use for observing space
a number of joint venture instruments
best known: the Canada-France-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii
What is depicted in this Image? What is it called, how many light years away? What does the red vs. green depict? What telescope was it taken from and when?
This is an image taken by the CFHT in 2004
This is the Lagoon Nebula, ~5000 light years away
* it is home to a cluster of very young stars, developing among globules and pillars of gas
the red colour depicts hydrogen
the green depicts oxygen
Note: You can see the Lagoon Nebula even without a telescope close to the constellation of Sagittarius
For what reason do we have telescopes orbiting outside earth’s atmosphere? The most famous one?
any telescope on earth has to make some compensation for earth’s atsmosphere and the distortions it creates
Thus the Hubble Space Telescope (HST) orbits some 600km above earth
Describe the characteristics of the HST:
- where does it orbit
- the size and shape
- is fitted with …?
- how often is it operated and how?
Hubble Space Telescope, which orbits ~600km above earth, has a 2.44 m mirror mounted inside a hollow tube (to avoid glare from the sun, moon and earth)
it is fitted with a great array of signal detectors
it is operated 24 hours a day remotely from earth
When was the HST launched? How many service calls has it had since then and how have they improved it?
What was installed during the last service call in 2009?
Why did NASA ban any further service calls to HST? What efforts were made to prolong its life in light of this?
Hubble Space Telescope was launched in 1990 and has had 5 service calls since; each scientific package that has been replaced on those calls has increased the telescope’s power by something like 10 times
The last service call in 2009 installed a wide field camera to see 3 types of light and a Cosmic Origins Spectrograph which breaks light into its component colours.
NASA announced they are banning any further service calls to HST because new safety regulations (arising from the Shuttle Columbia disaster) prohibit it.
In the last service call, it was replaced with all new parts to prolong its life as long as possible before it eventually falls to earth.
What is the JWST?
When is it scheduled to launch? Characteristics?
the James Webb Space Telescope is a replacement for the HST, scheduled to be launched into orbit around earth in 2018
this telecope will have a 6.5 meter in diameter mirror and a “sunshield the size of a tennis court” to allow astronomers to find galaxies and planetary systems.
The use of non optical telescopes is sometimes called what?
Invisible astronomy
All telescopes gather energy
what range of wavelengths of energy is gathered by optical telescopes vs. non optical telescopes
Optical telescopes gather wavelengths of energy between 400nm and 700nm - the very tiny band of energy that is visible light
Non optical telescopes gather wavelength energy beyond the visible spectrum (gamma rays, X-rays, ultraviolet, infrared, and radio waves)
Describe the detectable energy spectrum from the shortest to longest wavelengths
gamma rays → X-Rays → Ultra-violet → Visible Light → infared → radio waves
What was the first non optical telescope built to detect? When?
Since then what range have dishes been built to capture?
first non optical telescope build to collect radio waves in 1931
Since then, dishes have been built to collect every other possible range of detectable energy
What type of telescopes are carried on Rockets, satellites and space probes? Why?
they may carry optical cameras.
virtually all of them carry at least one type of non-optical telescope.
These allow scientists to gather data from wavelengths that Earth-based telescopes cannot easily capture, often due to atmospheric interference.
Describe the Lovell Telescope.
Size?
Where?
When was it built?
What purpose was it famously used for?
Is it still in use today?
One of the earliest large radio telescopes was the Lovell Telescope – a 76-meter dish at Jodrell Bank in the UK, built in 1957.
It was famously used to track Russia’s Sputnik 1 satellite.
Though it has been upgraded many times, it is still in use today and often works in conjunction with other telescopes to enhance resolution.
Describe what is being depicted in this image
Solar system bodies
Explain this image depicting the Nice and Grand Tack Models by time period.
What is Obliquity? If our theories of panetary formation in our solar system our correct, what would we expect for obliquity of planets? Is this the case? Why or why not?
Obliquity is the angle between Earth’s equatorial plane and its orbital pane (its eliptic)
If our theories of formation of solar system are correct, we should expect all planets to have the same sense of rotation and essentially a zero obliquity (the planets should coincide)
This is not the case: Mercury’s obliquity is pretty close to 0 but the others vary greatly.
Why?
most scientists believe that toward the end of the planet formation period - particularly at end of the planet suffle stage - the final few large collisions of large protoplanets/planetestimals knocked the planets askew.
(for example, venus has angle of obliquity of about 180 degrees, that means the planet began life with opposite sense of rotation or more likely that it was given such a hard knock that it started rotating on it’s head)
