First day of fall 2015 quotes, facts: Autumnal equinox is Wednesday

23 Sep 2015 | Author: | No comments yet »

Google Doodle celebrates the Autumnal equinox: where to see the colours change.

There are two equinoxes every year – in September and March – when the sun shines directly on the equator and the length of day and night is nearly equal. This is when the north and south poles of the Earth are not tilted towards or away from the sun, as at other times, but are aligned so as to give, theoretically, the same amount of daylight in both of the Earth’s hemispheres.

Equinox is derived from Latin, meaning “equal night” and on the equinox, night and day are nearly exactly the same length – 12 hours – all over the world, although in reality this isn’t exactly the case. No autumn is judged to have started on September 1 as otherwise the autumn date would change each year and it would be hard to compare different years. Several hundred miles south of New England, head for the Blue Ridge Parkway, one of the country’s most scenic roads, running for some 470 miles through Virginia and North Carolina. After all, the Earth’s orbit isn’t a perfect circle. “The Earth’s orbit is [only] about three percent out of round,” explains Jay Holberg, a senior research scientist at the lunar and planetary lab at the University of Arizona. “So in the northern winter—in December—the sun is actually closest to the Earth by a small amount, and in the summer it’s actually farther away.” So as Earth revolves around the sun, it maintains that tilt, and the sun’s light doesn’t hit the entire surface directly. According to the Forestry Commission, the first trees to start turning will be native species such as dogwood and common spindle in mid-September, followed by maples, rowans and ironwoods.

From mid-September each year, the “koyo front” moves south from Hokkaido towards the south of the country, which it typically reaches around late November, though there should be foliage worth seeing in Tokyo and Kyoto even into December. Of course autumn comes considerably later (or earlier, if you prefer) this far south, but it’s worth waiting till mid-April, peak season for the trees to sing out in spectacular yellow hues, especially next to the lakes and rivers around Tekapo, the Waitaki Valley and Central Otago. This discrepancy is partly due to an optical illusion: Earth’s atmosphere bends light, making the sun look like it’s above the horizon when it’s really below—just like a pencil stuck in a glass of water can look like it’s been split in two at the water line.

Autumn in Bavaria isn’t only about beer and pretzels – it’s perfect hiking weather, and the best time of year for magnificent views of forests, lakes and mountains south of Munich, as the pine trees turn. It changes with distance from the equator—which is why the poles have endless day in summer, and months of night in winter. “The equinox is defined as the time of an event. From the Chilean Lake District and Torres del Paine National Park, to Argentina’s southern Andes and the Perito Moreno Glacier, this is a truly spectacular and remote landscape with a huge variety of tree species which in April turn a glorious russet and gold.

Although it’s clear that the Maya built monuments to the changing seasons, the archaeological evidence is equivocal about whether there were any rituals around this building. “It’s sometimes very difficult to filter out the truth from the romance of the stones, that’s something you have to look at [in] the archaeological record, and legends,” Aveni says. Whether or not equinoxes carry any great cultural significance here on Earth, these celestial alignments link us with the rest of the planets in our solar system—except Mercury, which tilts pretty much perpendicularly to the sun. “It depends on whether you like seasons or not,” Holman says. “If you like the seasons, you probably want a modest [tilt] so that there’s some variation.” Mars looks pretty attractive. Its tilt exceeds ours by only a degree and a half, and its polar ice caps (made of dry ice rather than frozen water) freeze and thaw with the seasons just like our own.

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