astronomy@iowa

Early this morning physicists at the CERN—the European Center for Nuclear Research that straddles the French–Swiss border—activated the world’s most powerful particle accelerator. After a quarter century of dreaming and nearly 15 years of construction, several beams of protons were sent through the 17-mile beam ring that is buried 300 feet below the shores of Lake Geneva. Today’s test is a crucial first step on the path leading scientists to the unimaginably energy a mere trillionth of a second after the Big Bang. Eventually counter-circulating beams of protons (the proton is one member of a class of particles called hadrons) will collide to recreate those conditions.

In order to recreate those exotic conditions, the beams of protons must be accelerated to within a tiny fraction of the speed of light. Because Einstein’s special theory of relativity dictates that an object gains mass as its velocity increases (a hypothesis that has been experimentally verified time and time again) and also that mass and energy are equivalent. Thus, extremely high velocities are needed to produce the energies needed to test our theories of the early universe and the fundamental nature of mass itself. The LHC is expected to eventually accelerate protons to energies of 7 trillion electron-volts (7 TeV) where each electron-volt is the kinetic energy gained by a single electron as it moves through an electric field of 1 volt. The eV is the fundamental unit of energy used in nuclear physics.

By recreating conditions shortly after the Big Bang, physicists hope to glimpse evidence of the Higgs boson—a particle hypothesized to exist in those rarified conditions that is responsible for giving the property of mass, and thus inertia, to matter—as well as learn more about the elusive dark matter that accounts for anomalies in the rotation rates of galaxies and holds clusters of galaxies together. Dark matter is thought to account for as much as a quarter of the matter in the universe. One thing that the LHC is not expected to produce is an Earth-swallowing black hole. While “mini” black holes that are sub-atomic in size may be produced, if in fact they exist at all, the production of black holes that would spell doom for the earth is the stuff of fiction not science. No credible scientific evidence predicts that sort of scenario. In fact, Earth’s upper atmosphere is bombarded by cosmic rays of even greater energy every day and no mini black holes have been observed in those collisions.

One thing that is inescapable, however, is the bittersweet moment the test firing of the Large Hadron Collider represents. Even though the LHC is an international effort, the United States has relinquished its position as a leader in basic high-energy physics. Construction of the Superconducting Supercollider in Texas ended in 1993 when Congress looked for ways to save money and eliminated the funding after $2 billion dollars had already been spent. The SSC was to be an even bigger project than the Large Hadron Collider, whose construction was undertaken the year after the Superconducting Supercollider was killed. Although its budget eventually ballooned to $11 before being defunded, the SSC represented a mere 0.6% of the federal R&D budget for FY1992.

Given the politically-charged environment in which basic scientific research must be conducted today, CERN’s approach, with over 20 countries providing funding that is governed by treaty, may be the reality for the foreseeable future. Gone are the days of national pride in scientific achievement like those when physicist Robert Wilson was asked in a congressional hearing about the proposed FermiLab’s benefit to the United States’ national security. His reply: “It has nothing to do directly with defending this country except to make it worth defending.”

One hundred thousand orbits, that is…

On August 11 the Hubble Space Telescope completed its 100,000th orbit of Earth since being placed in orbit by the space shuttle Discovery in 1990. In the last 18 years the telescope has logged over 2.7 billion miles (that’s over 5,700 trips to the Moon!) while speeding at 5 miles per second.

To Commemorate 18 years of astronomical service, the Space Telescope Science Institute (STScI) is giving away 18 prints of the star cluster NGC 2074 taken to commemorate the orbital milestone. Visit the official website hubblesite.org and submit a valid email address after clicking the “Learn more” link for a chance to be one of the lucky winners to receive a 16×20-inch print.

Hurry, the drawing ends August 18.

The annual Perseids meteor shower is underway and should peak within the next 24 to 48 hours. According to estimates, the best time to observe the shower will be in the early morning hours of Tuesday, August 12. Although meteors will be visible at any time after dark, prime conditions will occur after the Moon sets about 2 a.m.

For more information on observing the shower and its cause, check out my web page at www.brentstuder.com/kcc/perseids.html.

Everything seems to be “Go” for an October 5 launch of the Interstellar Boundary Explorer satellite. Problems with the Pegasus rocket that will lift the satellite from its perch under the belly of a modified Lockheed L-1011 jumbo jet appear to have been resolved and IBEX has been delivered to Vandenberg Air Force Base for several weeks of testing before being mated to the Pegasus launch vehicle. Eventually the assembled vehicle will be flown under the Orbital Sciences Corporation’s L-1011 to the pacific island of Kwajalein for the October launch. By using the facilities at Kwajalein atoll for the mission launch instead of Cape Canaveral or Vandenberg AFB, mission planners will be able to utilize the additional eastward rotational velocity near Earth’s equator to increase fuel load by a precious few pounds and thus increase the final orbit of the 175-pound IBEX. To obtain the best data, the spacecraft must fly as far out of Earth’s magnetosphere as possible.

The Sun and entire solar system are moving through a region of space referred to as the local interstellar medium, which is composed of material ejected by stellar winds, novae and supernovae. The boundary between the local interstellar medium and the Sun’s sphere of influence is just now being studied and of considerable interest to astronomers now that the Voyager 1 spacecraft reached the termination shock in December 2004 at a distance of 94 Astronomical Units from the Sun (1 A.U. is the average distance between the earth and Sun.) The termination shock is the boundary layer where the particles from the solar wind begin interacting with material from the interstellar medium causing the solar wind to abruptly slow from a supersonic flow to a subsonic flow. Beyond the termination shock as some unknown distance is the heliopause—the layer at which the pressure of the solar wind is balanced by the pressure of the interstellar medium hitting the solar wind—and beyond that is the bow shock, where the interstellar medium first encounters the Sun’s influence.

The sole scientific objective of the IBEX mission is to discover the interaction between the local interstellar medium and the solar wind by answering several questions: What is the strength and structure of the termination shock, how are energetic protons accelerated by the termination shock, what are the properties of the solar wind flow beyond the termination shock, and how does the interstellar flow interact with the solar wind beyond the heliopause? The IBEX spacecraft will do this by investigating energetic neutral atoms of hydrogen generated primarily in the region beyond the heliopause. Because neutral atoms are unaffected by the presence of electric or magnetic fields, the detectors on IBEX will be able to map the points of origin of the neutral atoms it observes.

For more information about the Interstellar Boundary Explorer mission check out the IBEX website or get more immediate updates on IBEX at Twitter.

Talk about a lucky strike! On the night of January 9, 2008, astronomers were using the Swift satellite to observe a supernova in the galaxy NGC 2770—90 million light-years distant in the constellation Lynx—when another one popped off in the same galaxy. A supernova such as SN 2007uy occurs when a massive star runs out of nuclear fuel in its core and the outward flow of energy is insufficient to balance the crushing inward force of gravity. In an instant, the star’s core catastrophically implodes triggering a shock wave that races outward through the star. Astronomers have long suspected that when the shock wave bursts through the star’s surface, a short x-ray burst would be produced. Because of the timing of such an event, astronomers have only seen the optical brightening of the exploding star, which lasts for many weeks, but have never seen the short x-ray brightening. Until now, that is.

On that day in January, astronomers Alicia Soderberg and Edo Berger were observing SN 2007uy in the distant spiral galaxy when they detected an x-ray brightening lasting five minutes that did not coincide with the observed location of the supernova. Because of the fortuitous observation and the design of Swift, the astronomers were able to make numerous measurements of the new supernova (designated SN 2008D) and test the theory of x-ray break-out as the shock wave rips the progenitor star apart. Happily the observations of Soderberg and 38 other astronomers confirm the theory after nearly 40 years.

On July 31 laboratory tests aboard the Phoenix lander confirmed the existence of water in a Martian soil sample. The evidence came from vapors produced by the heating of the sample in an oven onboard the lander. Tentative evidence of water had previously been seen by the Mars Odyssey orbiter as well as disappearing chunks of white material in the soil below Phoenix early this summer.

Because of the success of the mission and overall good health of the spacecraft systems, the Phoenix mission has been extended an additional five week. Funding will now extend through September 30.

Additional information can be found on the mission website phoenix.lpl.arizona.edu.

At 11:59 UT¹ the Sun reached its most northerly point above the equator and marked the beginning of summer in the northern hemisphere. From the Latin name for the Sun (Sol) and sistere (meaning to stand still), solstice refers to the two times during the year when the Sun’s annual apparent motion around Earth’s sky reaches the most northerly and southerly extremes. The summer solstice—sometimes incorrectly referred to as the longest day of the year—is not any longer than other days of the year. The fact that the Sun reaches its most northerly point at the summer solstice simply means that today is the date that has the most daylight hours and the shortest night. And while we use this event to mark the beginning of summer in the northern hemisphere today, that has not always been the case.

Once referred to as midsummer (see “A Midsummer Night’s Dream“), the summer solstice once marked the middle of summer while the winter solstice marked the middle of winter and the two equinoces (“equal nights”) marked the middle of spring and autumn respectively. In some old European (such as ancient Irish) and East Asian cultures, the actual seasonal changes were related more to what are today called cross-quarter days. Based on modern calendars, these pagan celebrations fell at the beginning of November (Samhain), February (Imbolc), May (Beltane) and August (Lugnasadh) and are still observed today. Traditionally the new day began at sunset so many of these festivals span the eve and next morning.

Late October/Early November: Halloween, All Saints Day, All Souls Day
Early February: St. Brigids Day, Groundhog Day, Candlemas
Late April/Early May: Walpurgis Night, May Day
Early August: Lugnasadh, Lammas

The holiday that may be least familiar to those living in North America is Lammas. The Loaf-mass was a celebration of the first wheat harvest of the year and it was traditional to bring a loaf to church that was made from that first-harvest wheat.

While we often associate summer with the warmest season, it is wrong to assume the warmth of summer is due to our proximity to the Sun. Earth’s orbit is slightly eccentric (Kepler’s first law of planetary motion notes that planets orbit the Sun along elliptical paths), but distance is not the contributing factor to summer warmth. In fact, Earth is at its closest point to the Sun (perihelion) in early January and at its farthest point (aphelion) in early July! It is the inclination of Earth’s axis of rotation and the angle of sunlight striking Earth (see figure) that causes both the variation in daylight hours and efficiency of solar heating responsible for seasonal variations.

¹ UT refers to Universal Time and is the astronomical standard of time based on the mean solar time at the Greenwich meridian, which marks 0° longitude. To convert to the local time zone, simply add or subtract (taking daylight savings time into consideration!) the number of time zones between your location and the Greenwich meridian. For example, the Central Time Zone is 6 hours west of Greenwich so Central Standard Time  is UT – 6 hours while Central Daylight Time is UT – 5 hours. Hence, the summer solstice occurred at 11:59 p.m. – 5 hrs or 6:59 p.m. on June 20.

Image in link courtesy of Przemyslaw “Blueshade” Idzkiewicz. This work is licensed under the Creative Commons Attribution-ShareAlike 2.0 License.

Two years ago the International Astronomical Union (IAU) angered a lot of people when the Solar System’s ninth planet Pluto was demoted and designated a “dwarf planet” along with the asteroid Ceres and the recently discovered trans-neptunian object Eris. Well, the IAU has now come up with an official designation for Pluto and Eris that is almost guaranteed to upset people all over again. While some may think it’s a silly exercise to spend so much energy coming up with classification schemes (years ago the physicist Enrico Fermi complained about the number of sub-atomic particles saying “If I could remember the names of all these particles, I’d be a botanist.”), it is important for scientists to make classifications of the objects they study. The Greeks used the term “planetes astrum” to describe the wandering stars—as opposed to the “fixed” stars—but that definition did not really distinguish the actual planets from the Moon and Sun. But “Plutoid?”

The IAU Committee on Small Body Nomenclature defines a plutoid as “celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit.” For naming purposes, any body that meets these criteria and have an absolute magnitude brighter than H = +1 where H is the magnitude of the planet, asteroid, comet, etc. at one Astronomical Unit from the Sun.

In the above image, Pluto and its three moons are shown on the left while Eris is on the right.

Image Credit: IAU, NASA/ESA Hubble Space Telescope, H. Weaver (JHU/APL), A. Stern (SwRI), the HST Pluto Companion Search Team and M. Brown.

The following Oo-Ed piece by physicist Brian Greene appeared in the New York Times today:

Put a Little Science in Your Life

Emmy-award winning composer Alexander Courage died several weeks ago at the age of 88. Although he wrote musical scores for hundreds of television shows and movie musicals, he will be forever remembered as the composer of the theme to NBC’s television show “Star Trek.” He composed additional scores for just a handful of the show’s episodes, but did compose scores for many episodes of “Lost in Space,” which aired on rival network CBS.

After the end of World War II, Courage was discharged from the Army Air Corps and hired by MGM. While working for the studio he went on to arrange scores for some of the most famous musicals of the 1950s, including “The Band Wagon,” “Funny Face,” “Gigi” and “Guys and Dolls.”