Posted by Sadie from ? (184.108.40.206) on Monday, July 28, 2003 at 10:08AM :
CHECK OUT MARS IN AUGUST!!!
Never again in your (or my) lifetime will the Red Planet be so
spectacular. This month and next Earth is catching up with Mars, an
encounter that will culminate in the closest approach between the two
planets in recorded history. The next time Mars may come this close
is in 2287. Due to the way Jupiter's gravity tugs on Mars and
perturbs its orbit, astronomers can only be certain that Mars has not
come this close to Earth in the last 5,000 years but it may be as long
as 60,000 years. The encounter will culminate on August 27th when
Mars comes to within 34,649,589 miles and will be (next to the moon)
the brightest object in the night sky. It will attain a magnitude of
-2.9 and will appear 25.11 arc seconds wide. At a modest 75-power
magnification Mars will look as large as the full moon to the naked
Mars will be easy to spot. At the beginning of August Mars will rise
in the east at 10 p.m. and reach its azimuth at about 3 a.m. But by
the end of August when the two planets are closest, Mars will rise at
nightfall and reach its highest point in the sky at 12:30 a.m. That's
pretty convenient when it comes to seeing
something that no human has seen in recorded history.
So, mark your calendar at the beginning of August to see Mars grow
progressively brighter and brighter throughout the month. Share this!
No one alive today will ever see this again.
Thursday, July 1, 1999 Published at 09:54 GMT 10:54 UK
World's oldest telescope?
PICTURE: Is this the oldest telescope lens in the world?
By BBC News Online Science Editor Dr David Whitehouse
If one Italian scientist is correct then the telescope was not invented sometime in the 16th century by Dutch spectacle makers, but by ancient Assyrian astronomers nearly three thousand years earlier.
AUDIO FILE: BBC News' Dominic Hughes: This could mean that the telescope was invented two and a half thousand years earlier
According to Professor Giovanni Pettinato of the University of Rome, a rock crystal lens, currently on show in the British museum, could rewrite the history of science. He believes that it could explain why the ancient Assyrians knew so much about astronomy.
But experts on Assyrian archaeology are unconvinced. They say that the lens is of such low quality that it would have been a poor aid to vision.
It is called the Nimrud lens and it was found in 1850 by the legendary archaeologist Sir John Layard, during an epic series of excavations at the palace of Nimrud in what is now Iraq.
Upon his return to England, he showed the lens to physicist Sir David Brewer who thought it could have been used as a magnifying glass or to concentrate the Sun's rays.
Used as a magnifying glass, it could have been useful to Assyrian craftsman who often made intricate seals and produced minuscule texts on clay tablets using a wedge-shaped script.
It is a theory many scientists might be prepared to accept, but the idea that the rock crystal was part of a telescope is something else. To get from a lens to a telescope, they say, is an enormous leap.
Professor Pettinato counters by asking for an explanation of how the ancient Assyrians regarded the planet Saturn as a god surrounded by a ring of serpents?
Could they not have seen Saturn's rings through their telescope and interpreted them as serpents? An unconvincing argument, say experts. The Assyrians saw serpents everywhere. And why is it in their many astronomical reports on clay tablets there is no mention of such a device?
The conventional understanding of the invention of the telescope is that it was developed in the 16th century by Dutch spectacle-makers who held one lens in front of another.
One thing is sure: Galileo did not invent it - a common misconception - although he was one of the first to turn it towards the sky. By then, lenses used as spectacles had been known for hundreds of years at least, and it has been a puzzle to historians why it took so long for the telescope to be invented.
Commercial and military use
It may have been developed and then forgotten, or even kept secret. However, experts regard this as unlikely given the commercial and military uses that a telescope could serve.
Whatever its origin, as ornament, as magnifying lens or part of a telescope, the Nimrud lens is the oldest lens in the world. Looking at it evokes mystery and wonder. It can be seen in room 55 of the British Museum, in case 9 of the Lower Mesopotamian Gallery
It may not be unique. Another, possibly 5th century BC, lens was found in a sacred cave on Mount Ida on Crete. It was more powerful and of far better quality than the Nimrud lens.
Also, Roman writers Pliny and Seneca refer to a lens used by an engraver in Pompeii. So perhaps the ancients knew more about lenses than we give them credit for.
-- signature .
Post a Followup