Manhattan Sunset

Astronomy Photo of the Day

Photo by Neil deGrasse Tyson (AMNH)

Explanation: Every 28 May and July 12, Manhattan floods dramatically with sunlight just as the Sun sets precisely on the centerline of every street.

Usually, the tall buildings that line the gridded streets of New York City's tallest borough hide the setting Sun. This effect makes Manhattan a type of modern Stonehenge, although only aligned to about 30 degrees east of north.

Were Manhattan's road grid perfectly aligned to east and west, the effect would occur on the Vernal and Autumnal Equinox, March 21 and September 21, the only two days that the Sun rises and sets due east and west.

But with Manhattan aligned the way it is, it happens every May 28 and July 12. On none of these occasions, however, should you ever look directly at the Sun.

Follow me on Twitter: @IanYorston

DNA. A supermarket view...

DNA DL90 visualises Abigail Fallis's comment that 'shopping trolleys are everywhere, and have become a real symbol of modern society and today's consumer culture'. Her sculpture also alludes to scientific investigations into the designer baby, and the lengths society is prepared to go to ensure a perfect specimen. With the suggestion that consumerism has outstripped religion and other preoccupations in western countries, comes the argument that babies born into a first world society are born to shop.

The first edition of DNA DL90, seen in the grounds at Goodwood, was the result of the supermarket conglomerate Somerfield approaching the artist with a commission to create an artwork for the Muscular Dystrophy charity. Designed to focus public attention on the Muscular Dystrophy Campaign's work to fund scientific research into possible treatment and cures, DNA DL90 was also influenced by the 50th anniversary of the discovery of DNA's double-helix structure - fundamental to the understanding of muscular dystrophy itself.

Follow me on Twitter: @IanYorston

Beware the Ides of March

Julius Caesar's bloody assassination on March 15, 44 B.C., forever marked March 15, or the Ides of March, as a day of infamy.

For ancient Romans living before that event, however, an ides was merely one of several common calendar terms used to mark monthly lunar events. The ides simply marked the appearance of the full moon.

During the time of ancient Rome, each month began with the calends, from the Latin term meaning "proclaim" or "call." The term referred to the announcement of the first sighting of the new moon and was also associated with the day interest was due.

Following the calends came the nones, which marked the first quarter moon. Its meaning ("nine") was derived from the term for the Roman nine-day week, nundinae. One nundinae after the nones came the ides. The term, which means "to divide," designated the occurrence of the full moon.

The ancient Roman calendar fixed the calends on the 1st, the nones on the 5th or the 7th, and the ides on 13th or the 15th. The months of March, May, July, and October, the longest months at 31 days, held the nones on the 7th and the ides on the 15th. For all other months the nones fell on the 5th and the ides on the 13th.

Follow me on Twitter: @IanYorston

Welcome to the day...

Sed contra: "Olafur Eliasson: Weather Man", Archie Franks

We British are known for our obsession with the weather: we talk about it all the time, and it's part of a cultural stereotype that has been with us throughout living memory. Eliasson's incredible installation at the Tate Modern instead of mocking this stereotype has raised the importance of the weather in our society to a new level. Going to see Olafur's glowing sun has become a kind of pilgrimage for a lot of people, as lying underneath a ceiling of mirrors, looking up at an orange, glowing sun amidst an all-encompassing mist brings about a weird sense of nirvana.

Or, as the eighteenth-century writer Samuel Johnson famously remarked, ‘It is commonly observed, that when two Englishmen meet, their first talk is of the weather; they are in haste to tell each other, what each must already know, that it is hot or cold, bright or cloudy, windy or calm.’

Follow me on Twitter: @IanYorston