So many as the stars of heaven

posted: 2059 days ago, on Monday, 2009 Mar 02 at 07:48
tags: astronomy, Milky Way.

While pouring water into my coffee machine the other day, I thought about the rocky Atacama desert in Chile. With an annual average rainfall of zero mm, it is the driest place on Earth.

Cold ocean currents cause dry conditions inland, as is the case with the Namib. The Namib, however, is much less rocky than the Atacama, and looks a lot more like my idea of a desert: wall-to-wall sand.

Which always makes we wonder why in the Bible, when the idea is to convey "uncountable" (e.g. Gen 22:17, Heb 11:12), the "sands of the oceans" is used, and not "the sands of the deserts".

" so many as the stars of heaven in multitude, and as the sand, which is by the sea-shore, innumerable."

The Earth's surface measures 510 million square kilometres, of which 29% is land. Of this, a third is desert.

If just 10% of this is sandy desert, then there's 5 million square kilometres of desert on our planet. Let's say (very conservatively) that the sand is just 10cm deep. This gives us about 500 cubic kilometres of sand in total.

All the world's coast lines together stretch for one million kilometres. Of this, 36% is sandy coastline. Measured from high to low tide, the beaches are on average 50 metres across, and the sand lies about 5 metres deep. This gives 90 cubic kilometres of sand on all the beaches of the world.

Since a grain of sand is 1mm across, there are 900 billion billion grains of sand in the world's deserts, and a mere 200 billion billion grains of sand on all the beaches.

There's thus five times as much sand in the desert as on the beach.

Another Biblical allusion to "really a lot" is "as many as the stars in the heavens" (e.g. Neh. 9:23, 1 Cron. 27:23, Deut. 10:22 ).

" Look now toward heaven, and number the stars, if thou be able to number them: and he said unto him, So shall thy seed be."

" and in multiplying I will multiply thy seed as the stars of the heavens, and as the sand which is upon the seashore."

"And I will multiply thy seed as the stars of heaven, and will give unto thy seed all these lands."

Just how many stars are there in heaven?

From the centre of Cape Town one can sometimes see just two-dozen stars, on those evenings when the air pollution hangs like a dark nebula over the city. On a perfectly clear night, without the Moon, it will be difficult to count much more than 100 stars.

Light pollution robs city residents of the night sky. Poorly designed light fittings shine light upwards, achieving nothing more than illuminating the unmentionable bits of passing birds. And wasting money.

A light fitting with a shaded hood ensures that light goes where it is wanted, and nowhere else. Stupid lighting includes spotlights that are directed upward, and those round balls that look like tepid suns. Millions of Rands are wasted annually simply because stupid light fittings are used.

Urban light pollution brightens the natural night sky to such an extent that city dwellers visiting the countryside are astounded by the bright stars they can see. Yet the same stars shine over the city we are paying to blind ourselves.

Certainly the various authors of the Biblical books didn't have this problem. Each evening, "really a lot" of stars shone above them. In fact, the very same stars that shone down on Socrates, Julius Caesar, baby Jesus and Confucius, still shine above us in the night sky. Nothing's changed.

On a clear, dark, moonless night, you can see about 3,500 stars with the naked eye. Certainly, some seasons have more or less stars, and some people's eyes are better than others. But all-in-all, tallying both hemispheres, you're looking at a total of about 8,700 stars visible with the naked eye

There's certainly really a lot fewer stars in the heavens than grains of sand on the beaches. In fact, in just a single handful of sand you're holding about half a million grains.

What if "heavens" is taken to mean "the entire Universe"? Certainly, the Biblical writers didn't have a very grandiose view of the Universe their Earth was flat and the sky was stretched over it like a bowl or a tent.

So, how many stars are there in the Universe?

Before around 1690 and the use of the telescope for astronomy, our starry total stands at about 8,700 stars. What Galileo saw through his novel telescope changed how we subsequently view the Universe. What seemed like little clouds in the night sky, Galileo's telescope revealed as containing stars.

A typical pair of binoculars will show half a million stars to the patient observer.

That sounds like a lot, but it's just a handful. Our Milky Way is home to about 400 billion other stars. Recent Hubble Space Telescope observations indicate that there are about 130 billion galaxies in the Universe. Thus, there are 52 billion trillion (52, 000, 000, 000, 000, 000, 000, 000) stars in the Universe.

That's a lot more than the number of grains of sands on our planet's beaches. It's also a lot more than the number of people on Earth, which is somewhere around 5.5 billion people.

Hear Primo Levi, in The Periodic Table (1975):

" if all humanity, about 250 million tons, were distributed in a layer of homogeneous thickness on all the emergent lands, the "stature of man" would not be visible to the naked eye; the thickness one would obtain would be around sixteen thousandths of a millimeter."

Instead of homogenizing humanity, what if we just got them all together and had them stand side-by-side, each on his own one-metre square, like a massive chess board. Then the entire population of our planet would fit into a 74 square kilometre patch of ground about one-fifth of Lesotho, or one-two hundredth of South Africa's surface area.

If there were 52 billion trillion people (as many as there are stars) then there wouldn't be enough standing room on all the planets, dwarf planets and asteroids in our solar system in fact, you'd need another 400 billion similar solar systems to accommodate everyone.

However, instead of arranging them neatly on a chess board, let's say you just tossed them in a heap. This pile of people would be seven times bigger than the Earth. Its diameter would be 24,000 km, about the same size as a white dwarf star.

White dwarves are the last stages in the evolution of stars like our Sun, after all the nucular material has been used up. These exotic heavenly bodies will be examined in great detail by ALMA, the world's largest millimetre-wavelength telescope. And its currently being built in Chile, in the rocky Atacama desert.

nothing more to see. please move along.