The active Sun. The magnetic Sun White lightMagnetic field.
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Transcript of The active Sun. The magnetic Sun White lightMagnetic field.
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The active Sun
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The magnetic Sun
White light Magnetic field
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Solar magnetic fields reach far out into space
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Solar magnetic fields reach out into the outermost layer of the Sun’s
atmosphere…the corona
Temperatures in the corona are 1 - 2 million degrees Kelvin
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Your chance to see the solar corona
Total eclipse of the Sun…August 21, 2017
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The 11 Year Solar CycleThe Sun has a “heartbeat”; its
properties change on a period of 11 years
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Latest data on this sunspot cycle
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An indication that our knowledge of the solar cycle is far from perfect
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Predictions in 2007
Observations and predictions as of today
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Sunspots are the sites of big explosions (solar flares and coronal mass ejections)
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The Sunspot Cycle has been going on for a long time
Observations show cycle persisting, but “turning off” from 1650 to 1730 (Maunder Minimum)
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The Solar Wind
• A wind past the Earth at 400 km/sec
• The Sun is “melting away”• Density 19 orders of
magnitude less than atmosphere
• A medium for solar events • May have “sandblasted” the
early atmosphere of Mars
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The Lesson for Other Stars
• Do they also have sunspots, sunspot cycles, etc?
• How does all this (magnetic fields, solar wind, rotation) relate to the age of a star?
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Telescopes
The instruments we use to study the universe
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More about telescopes
• What you will be looking through later in the semester
• Progress in astronomy would have been impossible without them
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Telescopes do two things:
• Collect “Big Piles” of light
• Magnify object (it looks a lot closer than it is)
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Types of Telescopes
• Refractors
• Reflectors
• Radio telescopes
• None of the above
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Reflectors and Refractors
Newtonian
Cassegrain
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Refractors: more details from the book
Demo
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Reflectors: more details from the book
Demo
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Formation of an image
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Magnification of a telescope
The longer the focal length, the higher the magnification
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Modern astronomy: instead of an eyepiece, a Charge-Coupled Device (CCD)
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Keck Telescopes (Reflectors): 10 meter diameter
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Resolution: How small detail can you see with a telescope?
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Resolution: smallest angle measurable
Angle=wavelength/diameter(telescope)
(radians)
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Radio Telescopes
Wavelength large (1cm – 1 meter typically) so D has to be HUGE
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Radio Interferometers:
The ultimate in angular resolution
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Final topic: the disappearing night sky:The US by night; where is it dark?