APOD: Equinox Plus 1 (2010 Mar 21)

[APOD Robot]

Equinox Plus 1

Explanation: Twice a year, at the Spring and Fall equinox, the Sun rises due east. In an emphatic demonstration of this celestial alignment, photographer Joe Orman recorded this inspiring image of the Sun rising exactly along the east-west oriented Western Canal, in Tempe, Arizona, USA. But he waited until one day after the northern Spring equinox, in 2001, to photograph the striking view. Why was the rising Sun due east one day after the equinox? At Tempe's latitude the Sun rises at an angle, arcing southward as it climbs above the horizon. Because the distant mountains hide the true horizon, the Sun shifts slightly southward by the time it clears the mountain tops. Waiting 24 hours allowed the Sun to rise just north of east and arc back to an exactly eastern alignment for the photo. Today is another Equinox + 1 day, with the Sun crossing the celestial equator yesterday at about 17:32 Universal Time.

<< Previous APOD

Discuss Any APOD

Next APOD >>

[/b]

[henrystar]

How great to know some folks are looking! This photo brings home something that occurred to me as I was teaching astronomy last year. As Europeans and Africans spread across North America over the last 400 years, we built town after town ... all on a North South grid. As a result, for parts of each year, commuters have the sun in their eyes, going to work or coming home. Yet if, instead, we'd built the same grid of streets but at a 45 degree angle, NO commuter would EVER have the sun in her eyes! No doubt people have been killed in auto accidents for this silly reason!

[WallyWeet]

When thinking of and discussing something like this Equinox, do you think we humans will ever be able to speak of the earth moving rather than the sun? The earth could bow to maybe, or could slip under the image of, could revolve under or over the image of, for example. I think we hinder the development of reality in the minds of children of all ages when we continue to transgress reality by talking about the sun moving rather than the earth moving one in relation to the other.

[neufer]

How great to know some folks are looking! This photo brings home something that occurred to me as I was teaching astronomy last year. As Europeans and Africans spread across North America over the last 400 years, we built town after town ... all on a North South grid. As a result, for parts of each year, commuters have the sun in their eyes, going to work or coming home. Yet if, instead, we'd built the same grid of streets but at a 45 degree angle, NO commuter would EVER have the sun in her eyes! No doubt people have been killed in auto accidents for this silly reason!

<<Tenochtitlan was a Nahua altepetl (city-state) located on an island in Lake Texcoco, in the Valley of Mexico.

Founded in 1325, it became the seat of the growing Aztec empire in the 15th Century, until captured by the Spanish in 1521. It subsequently became a cabecera of the Viceroyalty of New Spain, and today the ruins of Tenochtitlan are located in the central part of Mexico City.>>

[Amir]

Hi everyone,
you ever heard of Persian Calendar (the one Iranians use)? it's really accurate and useful!
our year starts with Spring Equinox, the first day is called "Noruz", and it's the most important Holiday in our whole year, "Noruz" means "New Day".
the 3 Following Months contain 31 Day then we have Summer Solstice. National "Sun Dials Festival" is Held on this day.
next three months are all 31-Day which lead to Fall Equinox. then there are 5 30-day months and a 29-day one in the end of the year.
right in the middle of the last 6 months, which is Winter Solstice, there is "Yalda Night" celebration, which is not a Holiday, in fact the night is important, because it's the longest night throughout the year and is a turning point for day and nigh balance, days will be growing and that's a sign of Hope, that's why we celebrate the Night.
actually there are bunch of other celebration in the year that mostly go back to "Zoroastrians" culture, most of them are still celebrated today.
the first half of the year contains 186 days while the other half has 179 days, this shows that earth orbit the sun with a faster speed in the beginning of Summer than beginning of Winter.
this Calendar has been in use since Zoroastrians.

[owlice]

This is pretty cool; it clearly shows the southward shift of the rising sun: http://joeorman.shutterace.com/Sun/Sun_05.html

[Chris Peterson]

How great to know some folks are looking! This photo brings home something that occurred to me as I was teaching astronomy last year. As Europeans and Africans spread across North America over the last 400 years, we built town after town ... all on a North South grid. As a result, for parts of each year, commuters have the sun in their eyes, going to work or coming home. Yet if, instead, we'd built the same grid of streets but at a 45 degree angle, NO commuter would EVER have the sun in her eyes! No doubt people have been killed in auto accidents for this silly reason!

I would argue that a cardinal grid is actually the safest way to lay out roads. It is only on the equinoxes that the Sun rises directly east and sets directly west. For most of the year it is doing so well off the cardinal points- at the temperate latitudes where most people in the world live, the Sun ranges 30-60° north or south of east or west at sunrise or sunset. The Sun is moving north and south at its fastest rate near the equinoxes, so it actually spends less of the year east or west than it does to the north or south. At temperate latitudes, drivers in a 45° city would spend many more days driving into the Sun than they would in a 90° city.

[Chris Peterson]

When thinking of and discussing something like this Equinox, do you think we humans will ever be able to speak of the earth moving rather than the sun? The earth could bow to maybe, or could slip under the image of, could revolve under or over the image of, for example. I think we hinder the development of reality in the minds of children of all ages when we continue to transgress reality by talking about the sun moving rather than the earth moving one in relation to the other.

We quite properly express things in terms of frames of reference, and it would be quite bizarre to treat the apparent movement of the Sun in ordinary life as a movement of the Earth. While I would always teach kids how the solar system works, and where the motions we see come from, I'd also never hesitate to say something like "the Sun has moved quite a lot in the last hour" or "watch the Sun come up".

[henrystar]

You can see the angle of sunrise and sunset for yourself by using this calculator:

http://www.timeanddate.com/worldclock/a ... =-12&day=1

The azimuth is measured East of North: 90˚ is due East, 270˚ is due West. Try it for your location, for the extremes: December and June

[ta152h0]

and the Sun celebrates

http://www.spaceweather.com/images2010/ ... nn2qen04v7

[biddie67]

Years ago, when I was looking for a home to purchase, I purposefully looked for a house that was EAST of where I worked. That way the rising sun was at my back both when driving to work in the AM and returning home in the PM - sure saved wear-n-tear on my eyes over those years.

Amir - I found the description of your country's calendar fascinating - I had no idea such was in use!

[neufer]

Years ago, when I was looking for a home to purchase, I purposefully looked for a house that was EAST of where I worked. That way the rising sun was at my back both when driving to work in the AM and returning home in the PM - sure saved wear-n-tear on my eyes over those years.

However, such an arrangement is not recommended for werewolves.

<<A werewolf, also known as a lycanthrope (from the Greek λυκάνθρωπος: λύκος, lukos, "wolf", and άνθρωπος, anthrōpos, man), is a mythological or folkloric human with the ability to shapeshift into a wolf or an anthropomorphic wolf-like creature, either purposely, by being bitten or scratched by another werewolf, or after being placed under a curse. This transformation is often associated with the appearance of the full moon, as popularly noted by the medieval chronicler Gervase of Tilbury, and perhaps in earlier times among the ancient Greeks through the writings of Petronius.>>

[neufer]

The Thematic Mapper on NASA’s Landsat 5 satellite captured these natural-color images of Tempe Town Lake on July 12, 2010 (left), and July 28, 2010 (right). The difference in water level is most apparent near the west end of the reservoir. In the July 12 image, the lake’s west end is a uniformly thick band of water. By July 28, after the sudden draining of the lake, the west end of the reservoir appears as a thin, meandering stream and a few disjointed pools.

---

Tempe Town Lake Drain

<<Tempe Town Lake is an artificial reservoir on the Salt River (Rio Salado) where the river flows through the city of Tempe, Arizona. The reservoir was created through the use of inflatable dams—rubber-coated tubes of strong fabric affixed to concrete slabs. As part of a flood-prevention program, the computer-controlled tubes could be inflated or deflated, depending on water levels. On the evening of July 20, 2010, however, one of the dams burst, draining the reservoir and sending water down the Salt River.

By early 2010, authorities had noticed that some of the rubber on the inflatable dams was deteriorating, and replacement was scheduled to begin in February 2010, said local news reports. A severe winter storm, however, forced the postponement of repairs as the dams had to be deflated to accommodate a storm surge on the Salt River. Officials explained that water flowing through the dams prevented immediate replacement. After the dam burst on July 20, Tempe’s mayor stated at a press conference that reconstruction had already been scheduled to start on July 21. He described the timing of the dam breach as fortunate because, had the dam burst after repairs started, the event would have endangered repair crews.

The construction of Tempe Town Lake is just the most recent in a long pattern of human engineering along the Salt River, according to a timeline compiled by AZCentral. Native Americans are believed to have built an extensive canal system on the river as long ago as 500 AD. Much more recently, a “lakeside amusement park,” complete with an artificial lake, was constructed in 1949 on Tempe’s section of the Salt River, but seepage apparently caused the lake to dry up the following year.>>

[Moonlady]

I thought we get energy through the sun...what a myth! This picture prooves earthlings experts feed the sun with electricity transmission towers to let it shine