Happy Birthday GaelicSoxFan

[nwfisch]

Have a good one.

Hope Gordon wins 1 for your B-Day :tongue::tongue:

 

[inactiveuser1]

Happy Birthday

 

[Gustavus Adolphus]

The only dates when the sun rises and sets due east and west are the spring and fall equinoxes: March 21 and September 21 (the exact times vary and they can fall on the 20th as well). Between March 21 and September 21, the Sun is north of the celestial equator. It rises north of due east and sets north of due west. The closer to the Summer Solstice (June 21) and the farther north you go, the greater the deviation from due east and west. At 50 N the sun can deviate from due east and west by 38 degrees, and at 60 N the deviation can be 53 degrees. Just south of the Arctic Circle on June 21, the sun sets almost due north, dips briefly below the horizon, and rises again almost due north. On December 21, it peeps above the horizon almost due south and then drops back below, again almost due south.

It's flatly untrue that the sun never rises and sets north of due east-west except in the tropics. Between March 21 and September 21 the sun rises north of due east and sets north of due west everywhere on earth. The tropics are defined by what the sun does at noon. Outside the tropics the sun never appears overhead at noon. If the earth's axis tilt had increased to 49 degrees, it should be possible to photograph vertical objects with no shadow in International Falls, Minnesota near June 21. And of course, you can't.

The tropics are two parallels with latitude equal to the earth's axis tilt: 23.5 degrees. According to the axis-shift theory, the tilt is now 49.5 degrees, so the tropics are now at 49.5 north and south. Large cities with deep canyon streets would be a great place to test this theory. In New York, latitude 40.8 degrees, the sun should be directly overhead about May 18 and July 25. For Chicago (41.8 degrees) the dates would be May 20 and July 22. Skyscrapers should cast no shadows at noon. In between those dates at noon the north sides of buildings should be sunlit at noon and the south sides should be in shadow; the south side of the street should be sunlit and the north side should be in shadow at noon. Does that happen? (I don't care what happens at sunrise or sunset. Of course the north sides of buildings will be sunlit early in the morning and late in the afternoon. It's only noon that matters.)

Around the poles are two more parallels, the Arctic and Antarctic Circles, and these are at latitudes equal to 90 minus the earth's axis tilt, or 66.5 degrees. Above those latitudes there is at least one day when the sun never sets in the summer or rises in the winter. If the earth's axis tilt had increased by 26 degrees, the Arctic Circle would be at 90-49.5 = 40.5 degrees. This means that on June 21 the Sun would never set in New York City and on December 21 it would momentarily peep above the horizon at noon. Cities like Minneapolis and Seattle would have distinct summer periods of midnight sun and equally distinct periods of continuous night in the winter. I think that would make the news if it happened. (I know it seems like people never see the sun in the winter in Minneapolis and Seattle, but it does appear.)

If the earth's axis shifted by 26 degrees, what happened to geosynchronous satellites? If they still remained in their original orbits, then the satellites would appear to drift 26 degrees north and south of the celestial equator over the course of a day. Considering how touchy satellite dishes can be about misalignments of even a few degrees, this would totally disrupt global communications.

It gets worse. The earth's equatorial bulge causes satellite orbits to precess, or change their alignments. We make deliberate use of this fact with earth-observation satellites, so they repeat their tracks regularly over the earth and also view the earth under optimum lighting. It's not a problem for geosynchronous satellites orbiting in the earth's equatorial plane, but if the earth's axis were to shift, the satellites would no longer be orbiting in the earth's equatorial plane. The orbits would begin to precess. The orbits would be all over the sky (or at least that part of it within 26 degrees of the celestial equator) by now.

 

[inactiveuser1]

^

 

[Capt. Serious]

The only dates when the sun rises and sets due east and west are the spring and fall equinoxes: March 21 and September 21 (the exact times vary and they can fall on the 20th as well). Between March 21 and September 21, the Sun is north of the celestial equator. It rises north of due east and sets north of due west. The closer to the Summer Solstice (June 21) and the farther north you go, the greater the deviation from due east and west. At 50 N the sun can deviate from due east and west by 38 degrees, and at 60 N the deviation can be 53 degrees. Just south of the Arctic Circle on June 21, the sun sets almost due north, dips briefly below the horizon, and rises again almost due north. On December 21, it peeps above the horizon almost due south and then drops back below, again almost due south.

It's flatly untrue that the sun never rises and sets north of due east-west except in the tropics. Between March 21 and September 21 the sun rises north of due east and sets north of due west everywhere on earth. The tropics are defined by what the sun does at noon. Outside the tropics the sun never appears overhead at noon. If the earth's axis tilt had increased to 49 degrees, it should be possible to photograph vertical objects with no shadow in International Falls, Minnesota near June 21. And of course, you can't.

The tropics are two parallels with latitude equal to the earth's axis tilt: 23.5 degrees. According to the axis-shift theory, the tilt is now 49.5 degrees, so the tropics are now at 49.5 north and south. Large cities with deep canyon streets would be a great place to test this theory. In New York, latitude 40.8 degrees, the sun should be directly overhead about May 18 and July 25. For Chicago (41.8 degrees) the dates would be May 20 and July 22. Skyscrapers should cast no shadows at noon. In between those dates at noon the north sides of buildings should be sunlit at noon and the south sides should be in shadow; the south side of the street should be sunlit and the north side should be in shadow at noon. Does that happen? (I don't care what happens at sunrise or sunset. Of course the north sides of buildings will be sunlit early in the morning and late in the afternoon. It's only noon that matters.)

Around the poles are two more parallels, the Arctic and Antarctic Circles, and these are at latitudes equal to 90 minus the earth's axis tilt, or 66.5 degrees. Above those latitudes there is at least one day when the sun never sets in the summer or rises in the winter. If the earth's axis tilt had increased by 26 degrees, the Arctic Circle would be at 90-49.5 = 40.5 degrees. This means that on June 21 the Sun would never set in New York City and on December 21 it would momentarily peep above the horizon at noon. Cities like Minneapolis and Seattle would have distinct summer periods of midnight sun and equally distinct periods of continuous night in the winter. I think that would make the news if it happened. (I know it seems like people never see the sun in the winter in Minneapolis and Seattle, but it does appear.)

If the earth's axis shifted by 26 degrees, what happened to geosynchronous satellites? If they still remained in their original orbits, then the satellites would appear to drift 26 degrees north and south of the celestial equator over the course of a day. Considering how touchy satellite dishes can be about misalignments of even a few degrees, this would totally disrupt global communications.

It gets worse. The earth's equatorial bulge causes satellite orbits to precess, or change their alignments. We make deliberate use of this fact with earth-observation satellites, so they repeat their tracks regularly over the earth and also view the earth under optimum lighting. It's not a problem for geosynchronous satellites orbiting in the earth's equatorial plane, but if the earth's axis were to shift, the satellites would no longer be orbiting in the earth's equatorial plane. The orbits would begin to precess. The orbits would be all over the sky (or at least that part of it within 26 degrees of the celestial equator) by now.

 

[nwfisch]

That was a cool story Proper.

 

[Urblock]

Did Prope have a stroke?

 

[nwfisch]

Did Prope have a stroke?

Either that or a stick up his ass for no reason, I guess the latter.

 

[Gustavus Adolphus]

Did Prope have a stroke?

I thought Gaelic would enjoy an awesome astronomy mini-essay for his birthday.

 

[GaelicSoxFan]

Thanks for the birthday wishes.

In my family, there are four April birthdays, all within about a week. Me, my brother-in-law, nephew and one of my nieces. We celebrate them together. Last night we went out for dinner at The Patio in Orland Park (I had a pulled pork sammich), then had cake and presents at my sister's house. I got $200 in cash and a JCPenney gift card. I used most of the cash to buy a refurbished 32GB iPod Touch.

 

[GaelicSoxFan]

Have a good one.

Hope Gordon wins 1 for your B-Day :tongue::tongue:

U MUD ?

 

[Icculus]

Happy Birthday