Thursday, August 20, 2015
Thursday, July 9, 2015
Wednesday, July 8, 2015
Tuesday, July 7, 2015
Wednesday, July 1, 2015
Thursday, June 25, 2015
Home-Works and Midterm Exam
All previous home-works and the Midterm Exam are open till next Tuesday (6.30.2015 4:00 PM).
https://www.eztestonline.com/695230/index7.tpx
Every Home-work: multiple submission permitted.
Midterm Exam: only 1 submission permitted.
https://www.eztestonline.com/695230/index7.tpx
Every Home-work: multiple submission permitted.
Midterm Exam: only 1 submission permitted.
Last Attempt of Midterm-Exam
The Last Attempt to Increase Your Midterm-Exam Grade (Chapters 0-3).
ONLY 1 submission permitted.
Deadline: 06/30/2015 16:00
https://www.eztestonline.com/695230/14352756894633900838.tp4
ONLY 1 submission permitted.
Deadline: 06/30/2015 16:00
https://www.eztestonline.com/695230/14352756894633900838.tp4
Wednesday, June 24, 2015
Tuesday, June 23, 2015
What Does “Solstice” Mean?
The summer solstice marks the longest day of the calendar year and the beginning of summer in the Northern Hemisphere. But what does the wordsolstice mean, and what does it have to do with Shakespeare?
The term solstice is derived from the Latin scientific term solstitium. Containing the Latin sol- meaning “the sun” and sistere meaning “to make stand.” Today the term solstice is used to describe the exact moment when the sun reaches its northernmost point (around June 21) or southernmost point (around December 22) from the earth’s equator.
Summer lasts from the summer solstice to the autumnal equinox, one of two times a year when the sun crosses the plane of the earth’s equator, making night and day approximately equal length. Days lengthen from the winter solstice to the summer solstice, after which they begin to shorten.
William Shakespeare clearly had astronomy on his mind when he chose the title A Midsummer Night’s Dream, a tale of enchantment that takes place on midsummer’s eve, or, as we commonly refer to it, the summer solstice. Shakespeare is also credited with the first-known citation of the phrase “midsummer madness,” a line uttered by Olivia in Twelfth Night after encountering a cross-gartered Malvolio. This seasonal transition was thought to be a time when witches and other supernatural beings caused widespread mischief. Additionally, some plants were thought to possess magical healing powers and bonfires were thought to ward off malicious spirits. Midsummer’s Eve is a national holiday in Sweden and Finland.
How will you celebrate the upcoming solstice? Let us know.
Moon calendar June 2015
| Week | Su | Mo | Tu | We | Th | Fr | Sa |
|---|---|---|---|---|---|---|---|
| 23 | 1 | 2 | 3 | 4 | 5 | 6 | |
| 24 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| 25 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
| 26 | 21 | 22 | 23 | 24 | 25 | 26 | 27 |
| 27 | 28 | 29 | 30 |
Sunday, June 21, 2015
Home-Works
Do, please, home-works: https://www.eztestonline.com/695230/index7.tpx
All online home-works are opened now.
All home-works permit & record multiple submissions. Feel free to reach best results in home works by multiple submissions. Final grade is highest.
Be careful with the online midterm exam: The midterm exam permits only one submission.
Saturday, June 20, 2015
Friday, June 19, 2015
Previous Home-Works
All previous home-works are opened now till new deadline: 06/22/2015 16:00 https://www.eztestonline.com/695230/index7.tpx
Homework Chapter 4
Homework Chapter 4: https://www.eztestonline.com/695230/14347182554824200.tp4
Deadline: 06/22/2015 16:00
Midterm Exam Make-Up
The make-up for the midterm exam is opened online:
All students have permission and may increase grade.
However, ONLY 1 submission permitted.
Deadline: 06/22/2015 16:00
Wednesday, June 17, 2015
Grades for the Midterm Exam
Grades for the midterm exam are ready.
The number of correct answers is displayed for each student on the Blackboard.
The maximal number of the possible correct answers is 49 .
One question from the 50 total number doesn't have any correct answer because of an error in the problem text.
The symbolic student's grades have been calculated based on percent of correct answers and with the use of a curve method.
The number of correct answers is displayed for each student on the Blackboard.
The maximal number of the possible correct answers is 49 .
One question from the 50 total number doesn't have any correct answer because of an error in the problem text.
The symbolic student's grades have been calculated based on percent of correct answers and with the use of a curve method.
Tuesday, June 16, 2015
Light Collecting Power
If a 3 meter diameter telescope is doubled in size, then its new light collecting power would
- Not change.
- Double.
- Increase by a factor of four.
- Reduce by half.
- Not change.
- Double.
- Increase by a factor of four.
- Reduce by half.
Monday, June 15, 2015
Resolving Power
Another important power of a telescope is its ability to make us see really small details and see sharp images. This is its resolving power. Objects that are so close together in the sky that they blur together into a single blob are easily seen as separate objects with a good telescope. The resolving power is measured in the absolute smallest angle that can be resolved. The absolute minimum resolvable angle (smallest visible detail) in arc seconds 
= 252,000 × (observation wavelength) / (objective diameter). The wavelength and diameter must be measured in the same length units (i.e., both wavelength and objective diameter given in meters or both in nanometers). A telescope with one arc second resolution would be able to see a dime from about 3.7 kilometers (2.3 miles) away. Modern telescopes are able to count the number of lines in President Roosevelt's hair on a dime at that distance.
The desire is to make as small as possible. This can be done by making the observation wavelength small (e.g., use UV instead of visible light) or by making the objective diameter large. Another way to understand it is the more waves that can be packed on the objective, the more information the telescope detects and, therefore, the more detailed the image is. A 40-centimeter telescope has two times the resolution of a 20-centimeter telescope at the same observing wavelength ( for the 40-centimeter telescope is one-half the for the 20-centimeter telescope). However, fluctuations in the atmosphere will usually smear images into a fuzzy blob about one arc second or more across so the resolution is usually limited to the resolution from a 12.5-centimeter telescope on the ground. I will discuss the atmosphere's effect on images further in the another section and ways you can compensate for it.
= 252,000 × (observation wavelength) / (objective diameter). The wavelength and diameter must be measured in the same length units (i.e., both wavelength and objective diameter given in meters or both in nanometers). A telescope with one arc second resolution would be able to see a dime from about 3.7 kilometers (2.3 miles) away. Modern telescopes are able to count the number of lines in President Roosevelt's hair on a dime at that distance. as small as possible. This can be done by making the observation wavelength small (e.g., use UV instead of visible light) or by making the objective diameter large. Another way to understand it is the more waves that can be packed on the objective, the more information the telescope detects and, therefore, the more detailed the image is. A 40-centimeter telescope has two times the resolution of a 20-centimeter telescope at the same observing wavelength ( for the 40-centimeter telescope is one-half the for the 20-centimeter telescope). However, fluctuations in the atmosphere will usually smear images into a fuzzy blob about one arc second or more across so the resolution is usually limited to the resolution from a 12.5-centimeter telescope on the ground. I will discuss the atmosphere's effect on images further in the another section and ways you can compensate for it. | The desire for greater resolving power is the main reason why radio telescopes are so enormous compared to their optical counterparts. Radio wavelengths are LARGE so the radio telescope must be LARGE to get decent resolving power (and also to increase the signal strength of the low-energy radio waves---light-gathering power!). The Keck 10-meter telescope is considered a very large optical telescope. However, it is easily dwarfed by the HUGE 305-meter Arecibo Radio Telescope at the Arecibo Observatory. A picture of this telescope is shown at left. This telescope was built in a natural bowl-shaped valley in Puerto Rico. Clicking on the image will show the telescope from other perspectives. |
Thursday, June 11, 2015
Wednesday, June 10, 2015
Tuesday, June 9, 2015
Monday, June 8, 2015
Which of the two will be moving more slowly along its orbit?
Two artificial satellites are in circular orbits about the Earth. Which of the two will be moving more slowly along its orbit?
| The one with the smaller mass. | |
| The one with the larger mass. | |
| The lower one. | |
| The higher one. |
Saturday, June 6, 2015
Friday, June 5, 2015
What causes the seasons?
What causes the seasons?
The tilt of the celestial sphere with respect to the equator.
The Earth's distance from the Sun varies throughout the year.
The ecliptic is tilted with respect to the celestial equator.
The motion of the equinoxes.
None of the above.
The tilt of the celestial sphere with respect to the equator.
The Earth's distance from the Sun varies throughout the year.
The ecliptic is tilted with respect to the celestial equator.
The motion of the equinoxes.
None of the above.
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