August 2012 Sky from the Keeble Observatory
I had planned to write about the Curiosity probe, scheduled to land on Mars on the 5th of August. Since these landings are always high anxietyevents, I’d like to put that discussion off until September, with the hope that I can tell you about an exciting mission underway to further explore the Martian surface, rather than about a disappointing failure.
Instead, let’s try to understand the excitement over the July 4th announcement that the so-called “Higgs boson” had been discovered by two research teams at the large Hadron Collider. Which immediately makes us want to ask, “What’s a Higgs boson?” Indeed – what’s a boson, and who or what is a Higgs?
Subatomic particles in nature can be grouped according to their intrinsic angular momentum, known to physicists as spin, though that can be misleading to lay folks because nothing is actually spinning. Fermions (named after Italian physicist Enrico Fermi, although Paul Dirac also contributed to the mathematics which describe them) are particles with this spin property equal to half-integer multiples of Planck’s constant. (Actually, it’s Planck’s constant divide by two pi, but let’s not quibble.) These particles, which include electrons, protons, and neutrons, share the property that no two can share an identical state. Ultimately, this is the property that allows atoms to exist, and it explains the structure of the Periodic Table of the Elements. Bosons (named after Indian physicist Satyenda Bose, who along with Albert Einstein laid the theoretical underpinnings for their description) have integer spin. Any number of bosons can occupy the same state. Examples include photons, the quantum of light, and the assortment of particles that carry the other forces in the quantum description.
OK – enough jargon. In 1964 British theoretical physicist Peter Higgs suggested a mechanism to explain why various particles have different masses. The quantum description essentially adds an additional field as a property of space itself. As particles interact with this field they get mass – the more the interaction, the greater the mass. Photons do not interact with the field, and so are massless. Electrons interact less than protons, and so are less massive. And so on. Inclusion of this field rounds out the Standard Model, which is the framework which gives sense to the zoo of subatomic particles. If you “kick” this field at just the right energy (which is, unfortunately, not predicted by the theory, hence the long search to find it) we expect that a boson characteristic of the field will be produced. This is the so-called Higgs boson.
The other force-carrying bosons can be made manifest using particle accelerators (“atom smashers”) like the Large Hadron Collider at CERN, or the Tevatron at Fermilab in Illinois. For example, in a sufficiently energetic collision they can briefly produce W+, W-, and Z particles which carry the weak force. Other than the photon, which carries the electromagnetic force, the other “vector bosons” are unstable, and decay into a shower of other particles. The Higgs boson doesn’t carry a force, but it is unstable and decays almost immediately.
The search for the Higgs boson has been underway for decades. Using larger and larger accelerators capable of exploring larger and larger energy regimes, the search has been an exercise in futility. In a popular book about the search, Leon Lederman referred to the Higgs as “the God particle,” a name which most physicist detest. Indeed, Lederman is said to have blamed the title on his editor, claiming that he really wanted to call it the God***n particle because it resisted so many years’ efforts to find it.
In July, researchers from two separate collaborations agreed that they had probably seen it – or at least seen its footprints and its shadow – with less than one chance in several million that it’s a fluke. Further experiments are needed to confirm or refute whether this is the Higgs, or a “Higgs-like boson.” In a certain sense, this is where the fun begins, because some versions of the Standard Model predict several different versions of the Higgs boson! Stay tuned.
Lunar phases for August: Full Moon on the 1st, at 11:27 pm; Last Quarter on the 9th, at 2:55 pm; New Moon on the 17th at 11:54 am; First Quarter on the 24th at 9:54 am. And … another Full Moon on the 31st at 9:58 am! Since 1980, the second Full Moon in a calendar month has been known as a Blue Moon, though that’s not the original meaning of the term.
Pre-dawn planet watchers will find Jupiter and Venus gracing the eastern sky. Venus will be hard to miss, since it will be the brightest object in that direction until the Sun clears the horizon. Absent the presence of Venus, that honor would go to Jupiter, about 15 degrees above Venus and a bit to the right. As the month advances, Venus will appear closer to the Sun’s position, while Jupiteer climbs higher in the sky.
After sunset, Saturn and Mars will emerge from the evening twilight to the southwest, separated by about 5 degrees (just over the width of two fingers at arm’s length). Mars will be obvious – it’s the red one! They will move lower by month’s end, setting about an hour after sunset.
At midmonth, about 3 hours after sunset, we find the Summer Triangle (Deneb, Altair, and Vega) high overhead. Cygnus is at zenith, with Deneb marking the tail of the Swan. We’ve noted before that this constellation lies in the direction toward which the Sun is orbiting in the plane of the Galaxy. The solar system is moving at about 220 kilometers per second – but, so are the stars of Cygnus, so the shape of the constellation changes very slowly over the millennia. Vega is about 20 degrees to the west of Deneb, while Altair is about 30 degrees to the south.
Turning to the northwest, we see the familiar “big dipper” of Ursa Major. Following the two “pointer stars” at the end of the bowl to Polaris, the so called North Star, you’re facing a fraction of a degree from true North. Extending the line brings you to the constellation Cepheus, which looks like an inverted crude line drawing of a house … you know, a triangle on top of a rectangle. Here, the triangle is on the bottom. A bit to the right and below Cepheus is Cassiopeia, which looks like a W rocked back a bit counter clockwise. Follow the line of the bottom two stars (the left side of the W), and on a clear night you’ll find the faint glowing patch of the Andromeda Galaxy. As we’ve noted before, at a little over 2 million light years, this is the most distant object you can see with the naked eye.
The Milky Way arcs overhead from northeast to southwest, passing through Cygnus at zenith. Just above the southwest horizon, though it may be difficult to see through horizon clutter and haze, is the constellation Sagittarius, which marks the direction toward the center of the Milky Way. Consider the geometry. With the center at the southwest horizon and our direction of travel at zenith, just below Cassiopeia at the northeast horizon is the direction away from the center and out into intergalactic space. The northwest and southeast horizons mark the directions perpendicular to the plane of the Galaxy.
Copyright 2012George Spagna