Caption: "An animation illustrating the equatorial coordinates, ecliptic coordinates, and Galactic coordinates on the celestial sphere. Each set of coordinates is displayed for about 10 seconds." (Slightly edited.)
The equatorial coordinates are the main coordinates for astronomy.
Credit/Permission: © User:Tfr000, 2012 / Creative Commons CC BY-SA 3.0.
Image linked to Wikipedia.
Supplementary Lab Preparation: The items are often alternatives to the required preparation.
Caption: St. Nestor the Chronicler (c. 1056--c. 1114), St. Vladimir's Cathedral, Kiev, Ukraine.
At his studies.
Credit/Permission: Viktor Vasnetsov (1848--1926), 1919 (uploaded to Wikipedia by User:Butko, 2006) / Public domain.
Image linked to Wikipedia.
The quiz might be omitted if it's not feasible or convenient. The students may or may not be informed ahead of time of quiz omission depending on the circumstances.
The quizzes in total are 40 % of the course grade. However, only the top five quiz marks are counted.
In preparing for a quiz, go over the Required Lab Preparation.
The Supplementary Lab Preparation (see above) could help, but is only suggested if you feel you need more than the required Required Lab Preparation.
There is no end to the studying you can do, but it is only a short quiz.
One to two hours prep should suffice.
There will be 10 or so questions and the time will be 10 or so minutes.
The questions will range from quite easy to challenging.
The solutions might be posted at Celestial Sphere: Quiz Solutions after the quiz is given. Whether they are or not depends on the circumstances of each individual semester.
Caption: Plato (428/427--348/347 BCE) and Socrates (circa 469--399 BCE) in a Medieval image.
Here the disciple seems to be instructing the master/mentor using the Socratic method.
The basic pose is much like in intro labs.
Credit/Permission: Medieval artist, Middle Ages (probably 1000--1400) (uploaded to Wikipedia by User:Tomisti, 2007) / Public domain.
Image linked to Wikipedia.
There should be piles in the storeroom (Bigelow Physics Building (BPB) Rm 252), but if not there should be a set to photocopy or they can be downloaded from Lab 2 sky maps.
Actually, students are happy to just pick them up from a spread out pile. Sometimes you just have to do it that way.
At a convenient time before or after the Startup Presentation, get the student names in their groups. This gives you a record for the new groups, attendance, and a cheat sheet for their names.
But one needs a little warm up to get the students started.
I personally think that 15 minutes of Startup Presentation is the usual max---I aim at 10 minutes actually.
Caption: "Red foxes (Vulpes vulpes) at the British Wildlife Centre, Horne, Surrey, England." (Slightly edited.)
Credit/Permission: © Keven Law, Photo 2008 Aug17 / Creative Commons CC BY-SA 2.0.
Image linked to Wikipedia.
This inside laboratory continues with sky orientation and introduces the celestial coordinate systems. It especially emphasizes how the appearance of the sky changes with the changing seasons and how it depends on the observer's location on the Earth.
The applet below gives the essentials of the horizontal coordinate system.
The animation below gives the essentials of the equatorial coordinate system.
Caption: An animation illustrating the celestial sphere, equatorial coordinates, right ascension (RA), declination (Dec or δ), north celestial pole (NCP), south celestial pole (SCP), the celestial equator, the vernal equinox, the ecliptic, and the locations of Aldebaran and Sirius.
The equatorial coordinate system is essentially a projection (as viewed from the center of the Earth) of the geographic coordinate system onto the celestial sphere.
Longitude transforms to right ascension (RA) and latitude transforms to declination (Dec or δ), mutatis mutandis:
Why is equatorial coordinate system good?
The relationship between the celestial meridian and right ascensions is particulary easy to understand.
Celestial meridian is all at one right ascension at any instant in time and that right ascension increases throughout the day until in rolls over when the vernal equinox transits the meridian.
So declination tells us what is above the horizon.
Declination is also, of course, the orthogonal coordinate to right ascension, and therefore the easy one to use with right ascension.
As an example of converting from equatorial coordinates to horizontal coordinates (which are attached to the observer's location on Earth), the altitude from due north of an astronomical object transiting the meridian is given by the following simple formula:
Alt=90+Lat-δ , where Lat is latitude (counted as negative if south latitude) and δ is declination. If Lat=δ, Alt=90 degrees which is zenith.
Credit/Permission: © User:Tfr000 / Creative Commons CC BY-SA 3.0.
Image linked to Wikipedia.
The applet below illustrates the relationship between the horizontal coordinate system and equatorial coordinate system.
A celestial globe is a representation of the celestial sphere.
There is celestial globe on your bench.
Everyone touch them or trace with your finger along them: celestial globe and identify the celestial equator, celestial axis, north celestial pole (NCP), south celestial pole (SCP), and the ecliptic.
Every day (really every sidereal day) from a stationary Earth perspective, the whole celestial sphere spin WESTWARD around on the celestial axis carrying all the astronomical objects.
Of course, the astronomical objects do move relative to the celestial sphere due to their proper motions in space.
Except for most artificial satellites, the proper motions are slow compared to the WESTWARD revolution of celestial sphere and can often be neglected depending on the case.
Declination (dec) is pretty much just like latitude: it is measured north and south from the celestial equator.
Right ascension (RA) is pretty much like longitude, except that it is only measured east from the vernal equinox and makes use of the angular measure unit hour equal to 15 degrees.
Why hour?
Well the celestial equator rotates 1 hour in 1 hour---really 1 sidereal hour.
Everyone find the vernal equinox on your celestial globe and trace with your finger eastward observing the RAs.
There is some fun geometry in the two figures below.
You can comprehend them at your leisure.
Caption: NCP altitude equals latitude provided one counts south latitudes as negative latitudes.
Note that the NCP/celestial equator is so remote from Earth that lines heading toward the NCP/celestial equator starting from any point on Earth are parallel.
The diagram then clearly shows for a general point on the Earth's in the Northern Hemisphere that
Alt_N_NCP=Lat ,
where Alt_N_NCP is the
altitude
from due north on the
horizon to the
NCP.
If you imagine sliding the general point to the Southern Hemisphere, you see that the formula remains valid provided you count south latitudes as negative latitudes.
In the Southern Hemisphere, the NCP is below the horizon, and so its altitude is negative.
Caption: The conversion of declination to altitude for an astronomical object transiting the meridian.
The diagram derives the conversion formula.
The night sky continually shifts eastward due to the Sun's apparent motion around the celestial sphere on the ecliptic.
It means "as seen from the Earth".
The applet shows the continual progression of the night sky opposite the Sun
The animation, figures and applets below summarize the seasons.
You can comprehend them at your leisure.
Caption: An animation of the Earth's orbit around the Sun.
Over short time periods like a year and a human lifetime, the direction of the Earth's axial tilt is relatively constant with respect to the fixed stars, and there also with respect to ecliptic pole which is perpendicular to the ecliptic plane which is the plane of the Earth's orbit.
The varying average amounts of insolation (solar energy per unit time per unit area) received by the Northern Hemisphere Southern Hemisphere are the causes of the seasons.
The Northern Hemisphere is in summer when the north end of the Earth's axis is tilted toward the Sun and in winter when it is tilted way.
In between, one has the in-between seasons, spring and fall.
The Southern Hemisphere is the mirror case.
Credit/Permission: © User:Tfr000, 2012 / Creative Commons CC BY-SA 3.0.
Image linked to Wikipedia.
Caption: At the equinoxes.
The Earth's axis is tilt in the direction perpendicular to the plane of the diagram.
Caption: An animation of the axial precession.
The axial precession of the Earth causes a circular rotation of the north celestial pole (NCP) on the celestial sphere.
The period of the axial precession is about 26,000 years.
There is no accurate way to predict its value beyond a few thousand years to the past or the future.
If the current rate is taken as constant, the period would be almost exactly 25,771 Julian years (which are exactly 365.25 days).
But since that rate is not constant, about 26,000 years is about the most accurate one can be.
On 2100 Mar24, NCP will make its closest apparent approach of about 28 arcminutes to Polaris. (see Wikipedia: Pole star: Historical).
Circa year 4000 CE, NCP will make its closest approach of about 2 degrees to γ Cephei (apparent V magnitude 3.22) which will then lay a claim to being the pole star of the north.
Circa year 10,000 CE, NCP will make its closest approach of about 5 degrees to the bright star Deneb (apparent V magnitude 1.25) which will then lay a claim to being the pole star of the north.
One wonders who will notice.
Credit/Permission: © User:Tfr000, 2012 / Creative Commons CC BY-SA 3.0.
Image linked to Wikipedia.
Caption: Film poster for the TheMummy (1932) starring Boris Karloff (1887--1969).
Credit/Permission: Employee or employees of Universal Pictures attributed to Karoly Grosz (fl. 1930s), 1932 (uploaded to Wikipedia by User:Crisco 1492, 2012) / Public domain.
Image linked to Wikipedia.
Any that are semester-section-specific will have to added as needed.
You have to raise your game.
The definitions required for the reports are those that are relevant to astronomy and NOT other topics.
Sentences begin with a capital letter letter and end with a period. Usually there is a subject and a verb. Not always.
Since you are working in groups, you should have different group members read over the sentence answers to see if they are correct and comprehensible. Read them out loud.
Usually it is obvious what those questions are. Sometimes maybe not. Err on the side yes an explanation is needed.
