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
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.