During the first two weeks of March, look for tiny Mercury along the due west horizon during evening twilight. This little planet is smaller in diameter than the moons Titan and Ganymede but more than twice as massive.
Soon after sunset, Venus is the brightest object in the western sky. On the evenings of March 12 and 13, Venus and Jupiter will be only 3 degrees apart. Don't miss this beautiful pairing. Then, on March 26, a thin crescent moon will be very close to Venus.
Mars reaches opposition on the night of March 3, when it is directly opposite the sun as seen from Earth. During the first week of March, it approaches closest (63 million miles) to Earth and appears brightest for all of 2012. In fact, through a telescope, Mars will not appear this big and bright until 2014. The Red Planet rises in the east near sunset and sets in the west around sunrise.
Astronomers using spectral analysis have determined that the outer stars in certain spiral galaxies orbit just as fast as those near the center. The gravity from only the visible matter would not be enough to hold the galaxy together. Invisible dark matter must add to the galaxy’s gravitational influence.
Image courtesy of NASA, ESA, STScI
Normal matter that we can see, such as stars, galaxies, vast glowing gas clouds, planets, etc., makes up only about 4 percent of the universe. The rest is dark matter, that doesn’t emit or reflect light, and invisible dark energy.
Image courtesy of NASA
Located about 3.5 billion light-years from Earth, Pandora’s Cluster is the jumbled collision site of multiple galaxy clusters. The diffuse cloud in the center consists of extremely hot X-ray emitting gas and invisible dark matter.
Image courtesy of NASA, ESA, STScI
Type 1a supernovae, like this one that was detected in 1994 in the disk galaxy NGC4526, have been used to calibrate a precise brightness-distance relation, enabling astronomers to estimate the expansion rate of the universe.
Image courtesy of High-Z SN Search Team, HST, NASA
This massive galaxy cluster (MACS 1206) lies 4.5 billion light-years from Earth. The cluster acts as a giant cosmic lens, magnifying, distorting and bending any light passing through it, creating an effect known as gravitational lensing.
Image courtesy of NASA, ESA, CLASH Team
Jupiter, the second-brightest planet, pairs up with Venus to put on a dazzling show in the western sky during evening twilight. Although they appear close together on the evenings of March 12 and 13, in reality they are quite far apart. Venus is now 74 million miles away but Jupiter is seven times farther. At dusk on March 25, a thin crescent moon will appear close to Jupiter.
Saturn rises in the east-southeast during the late evening hours and is high in the south-southwest predawn sky. This beautiful planet spins so fast on its axis that it flattens out the top and bottom of the globe and forces the equatorial region to bulge out.
Daylight Saving Time begins at 2 a.m. on March 11 for most of the U.S.
The sun crosses the celestial equator at 1:14 a.m. EDT on March 20, marking the Spring Equinox. This is the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. On the days of the equinoxes, the hours of daylight and darkness are equal.
DARK ENERGY, DARK MATTER
''Both dark matter and dark energy could be two faces of the same coin.'' - Dr. HongSheng Zhao, Univ. St. Andrews
Twenty years ago, scientists thought that they knew pretty well the future of our expanding universe. They thought that gravity would either stop the expansion altogether and eventually a recollapse would occur or else the force of gravity would at least eventually slow down the expansion over the eons. However, the Hubble Space Telescope allowed astronomers to observe extremely remote supernovae that showed the expansion of the universe is not slowing due to gravity but it is actually expanding at an accelerating rate. This was totally unexpected and left scientists searching for a cause.
The universe that surrounds us isn't really what it seems to be. All of the trillions upon trillions of stars amount to less than 1 percent of its mass. All of the vast nebulas of gas and dust in the billions and billions of galaxies and all other forms of ordinary matter make up about 4 percent of the mass of the universe. This means that the force of gravity from all the stars, galaxies and atoms in the universe is insignificant when compared to the mysterious new energy field that is pushing the galaxies apart and causing the universe to expand faster and faster. Scientists now believe that 23 percent of the universe is composed of ''dark matter,'' the invisible particles that don't emit or reflect light but which create gravitational attraction and allow galaxies to form. The rest of the entire universe (73 percent) is composed of ''dark energy.'' The word ''dark'' is used because we know extremely little about these strange forces.
Dark energy is by far the biggest constituent of the universe and, right now, is also the biggest mystery in the entire field of science. Studies during the last couple of decades have shown that, in the early universe, the expansion from the Big Bang was actually slowing down due to the attractive force of gravity. However, as galaxies moved further and further apart, gravity's attractive force gradually weakened and the elusive force we call dark energy, became dominant. At the present time, dark energy is far more powerful than the force of gravity. In another few billion years, it may be strong enough to rip our galaxy apart.
Since these esoteric forces do not directly affect us at the present time, should we simply disregard them? No way. Our increasing knowledge of atomic particle interactions, relativity, quantum gravity, quantum physics, and space-time has enabled us to discover numerous advances in technology over the years. The computerized robots in industrial assembly lines, the electronics in your iPod and iPad, the GPS device in your car, the innovations in aircraft design and manufacture are all derived with help from previous decades of basic physics research. Astronomers were at the forefront of advances in electronic imaging devices (CCDs) now used in consumer digital cameras. Medical diagnostic imaging equipment is based on the scattering of light and particles by matter. Soon we can expect simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) to provide the broadest spectrum of diagnostics possible. The X-ray scanners in airports were developed with the help of astronomers who were originally interested in detecting X-rays from stars and galaxies. Who knows, someday far in the future our life here on Earth may be influenced by our understanding of how dark energy could be a property of ''empty'' space.
Editor's note: This monthly guide to the stars is from the Marshall Martz Memorial Astronomical Association, the Southern Tier Astronomy Recreation Society and The Post-Journal. For further information, contact the M.M.M.A.A. at www.martzobservatory.org or S.T.A.R.S. at www.UpStateAstro.org/stars/stars.html.