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Friday, October 28, 2011

Jupiter at Opposition Tonight

Jupiter reaches opposition with the sun today. This means it is the closest to the earth in this year's orbit around the sun. Like all planets at opposition ("opposite" the sun in the sky), it rises at sunset and sets at sunrise. It will be well placed for viewing throughout the rest of the Fall and Winter months.

Jupiter shines at magnitude -2.9 and shows a disk of 49.7 seconds of arc, just a fraction smaller than last year and as big as it has been since 1962. It is "just" 593.9 million kilometers, or 33.02 light minutes, distant. It seems to be huge in my 102mm refractor, with lots of detail showing in the cloud bands that cross the planet. The Galilean moons continue their dance around the planet, adding a charming note to the view.

The Danish astronomer Ole Roemer was the first scientist to use the varying distance of Jupiter at opposition and at conjunction to estimate the speed of light, using the timing of transits of Jupiter's moon Io in the 1670s. He came up with a speed of 186,000 miles per second, almost right on the money.

Make sure you take some time to go out and view the planet during this opposition. The 4 Galilean moons should be visible in even small binoculars, although probably not all at the same time. Through even a very small telescope all 4 Galilean moons are easily visible, together with a wealth of detail on the planet. The orbit of the moons around Jupiter was one of the pieces of evidence that Galileo cited in support of the then still controversial heliocentric theory of Copernicus over against the geocentric theory of Ptolemy and the theologians of his time. You can go out and observe this piece of evidence with your own eyes tonight. It doesn't get more exciting than that!

Position of a superior plant (beyond the orbit of the Earth) at opposition, as Jupiter is now, and at conjunction.

- by Ira Machefsky
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Tuesday, October 25, 2011

Mooned out for the Draconids Meteor Shower

Did you go out and watch the Draconids on October 8th? There was a meteor storm predicted, with meteor rates in excess of 750 per hour. We were out at our observing location and counted only a disappointing 2 meteors from 8:30PM - 10:00PM. Our sky conditions were very poor. Not only was there a nearly full moon in the sky, but there was also a high, thin haze that spread the moonlight across most of the sky. We even had a hard time seeing second magnitude Polaris, the Pole Star. Others in Israel and beyond counted much higher numbers, their skies presumably not affected by haze. Better luck next time.

A lone Draconid streaks across the October sky.

- By Ira Machefsky

Did you bet against Einstein? You lost!

As we foretold, the surest way to lose your money is to bet against Einstein. The hoopla over the discovery of neutrinos that allegedly (as they say of criminals) traveled faster than light (superluminal neutrinos) has died away, with only faint traces of pie left on the faces of the researchers at CERN, who forgot to take account of special relativity in timing the travel of the neutrinos between Geneva and Gran Sasso in Italy. The scientists at CERN used the highly accurate clocks in GPS satellites orbiting high above earth to synchronize their clocks in the laboratory. But they neglected to take account of the relative motion between their laboratory clocks and the GPS satellites, which accounted for a 32 nanosecond error in each direction of travel, almost exactly amounting to the 60 nanoseconds faster than light that the neutrinos were supposed to have traveled. Sic semper gloria mundi.

Neutrinos travelling between CERN in Geneva and Gran Sasso in Italy were mis-timed due to the relative motion between the two locations and GPS satellites in orbit above the earth.

Tuesday, October 11, 2011

Cold Fusion - It's B-A-C-K

While we're on the subject of disruptive science, here's one you probably haven't heard about, since the mass media seem to be ignoring it, probably because claims about cold fusion have been proven bogus so often in the past. But, on October 6th this year physicist Andrea Rossi demonstrated his energy catalyzer or E-cat in Bologna, Italy before a group of invited scientists from around the world. It generated lots of heat over a period of four hours with no visible input. This doesn't mean it's the real deal, but of course this would change everything if it were true. We would be able to cancel every country's deficit just by turning the thing on for a few years. Everyone remains skeptical, but you can follow the progress of future tests here, some scheduled for the end of this month.

--by Ira Machefsky
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The Speed of Light - "Not just a Good Idea, It's The Law" Challenged

It's been a disruptive few weeks for physics. First scientists at CERN report possibly finding particles (neutrinos) that travel slightly faster than the speed of light (c), formerly thought to be the cosmic  speed limit. They've asked for scientists around the world to confirm their findings or show where they have gone wrong. The neutrinos arrived 60 nanoseconds (a billionth of a second) faster than expected. This is an exceedingly short, but significant, time, amounting to a distance of some 60 feet in the 500 or so miles the experiment involved.

Although the press touted this as possibly proving Einstein wrong, that was a bit of an exaggeration. General relativity has been tested and confirmed so many times that Einstein would be proven no more "wrong" by this than Newton was proved "wrong" by Einstein. You can still send rockets to the planets using good-old Newtonian mechanics without considering general relativity at all. Newton's laws are a very good approximation of how gravity works, within the limits where Newtonian physics is valid. The same would be true for Einstein's general theory of relativity. We'll have to wait to see how this turns out, but I have a feeling that Einstein will be vindicated.

One reason for this has to do with neutrinos from supernova 1987A in the Large Magellanic Cloud, our nearest galactic neighbor at 168,000 light years distant. Supernovas release copious amounts of neutrinos a short time before the light from the explosion is emitted. At the distance of the Large Magellanic Cloud those neutrinos should have arrived a year before the supernova itself became visible, if neutrinos do indeed travel faster than light. Instead they arrived just a short time before, as predicted by current theory and a cosmic speed limit for light of 186,000 miles/second.

There's an old saying in physics that the surest way to loose alot of money is to bet against Einstein. Or you could play the stock market.

--by Ira Machefsky
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Wednesday, October 5, 2011

Draconids Meteor Storm - This Could Be Very Big...

...or not. This year the Draconids meteor shower peaks on the night of October 8th, right after the end of Yom Kippur. Scientists this year are predicting a possible meteor storm from the Draconids, a condition in which over 750 meteors per hour might be seen. Let me do the math for you - that's over 12 meteors per minute. The Draconids, formerly called the Giacobinids, come from our encounter with the orbit of comet Giacobini-Zinner, which passes our way every 6.6 years. Every time it orbits the sun it lays down a stream of particles, kind of like a family in a car throwing litter out the window as they go along. Most years, we pass through the streams without touching them, or just grazing them. This year, we are predicted to have a head-on encounter with three of the streams!

In the late 1880s the comet had a close encounter with that big, bad boy of planets, Jupiter, which altered its course and made predicting its streams uncertain. But in 1933 there were over 10,000 Draconids per hour reported, and also large outbursts in 1946 and lesser ones in 1985, 1998, and 2005. So, this is predicted to be a big year. As always, there is a fly in the ointment, or rather a moon in the sky. The moon will be nearly full on the 8th, and it's light will block all but the brigthest meteors, considerably reducing the number visible even should a meteor strom occur. Still, it could be quite a nice sight nonetheless.

The meteor shower is predicted to have a number of peaks, as the earth encounters the orbit of the streams throughout the night, starting at 8:00PM Israel local time through 1:00AM Sunday morning. Israel is perfectly placed for this display since it begins to occur early in the evening after Yom Kippur and continues for another five hours. In any case, we are much better than the US where the peaks all occur in broad daylight (and on Yom Kippur day).

To observe the meteor shower you can look anywhere in the sky. You should just have a clear horizon and as little additional light pollution as possible. Mitzpe Ramon, or any desert location in the Negev, will be perfect for this, but I don't expect many people to come down after Yom Kippur. Just go outside, if you have no other choice, and look up!

Comet Giacobini-Zinner, as seen in 1998.

You might also be interested in: Draconid Meteor Outburst


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What's that bright object in the east early in the evening?

We have been getting alot of this question by phone and email from sky watchers. That very bright object in the east-northeast just after the end of twilight is Jupiter, now shinning at magnitude -2.8 in the constellation Aries. It is so bright now that you can become gobsmacked just looking at it from a dark sky. Jupiter will come to opposition on October 28th, when it will rise as the sun sets and be in the sky all night long. In a telescope Jupiter now presents the largest planetary disk of all the planets in the solar system, 48" of arc in diameter. This disk is, of course, to small to see with the naked eye, but it may be just visible in 10x binoculars. In a telescope it looks gigantic at high power.

If you have binoculars, be sure not to miss the 4 Galilean moons -- Io, Europa, Ganymede, and Callisto -- at least some of which are easy to spot in binoculars depending on their orbital location. You can watch their position change over the course of an hour, an example of a mini-solar system and gravity at work!

Jupiter, at center (over exposed), surrounded by the four Galilean satellites, named after their discoverer, Galileo Galelli.

And remember to "Keep on Looking up!"


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