Mercury is behind the sun in relation to Earth and is not visible this month.
Brilliant Venus appears as a beautiful "Morning Star" during September. Look for it in the eastern predawn sky, where it continues to shine in morning twilight. Venus will sink lower in the east each morning until the end of the year.
The reddish glow of Mars can be spotted low in the southwestern evening twilight. The supergiant star Antares appears to move closer to Mars throughout the month. Both have a reddish appearance, and it's easy to confuse the two.
Jupiter rises in the east-northeast at midnight early in September but about two hours earlier at the end of the month. The best time this month to observe the giant planet with a telescope is in the predawn hours, when it's high in the sky.
Beautiful Saturn gives off its soft glow to the right of fainter Mars, in the southwestern evening sky. The blue-white star below Saturn is Spica. Both Saturn and Spica appear lower each night, disappearing into the solar glare at the end of September.
The sun arrives at the Autumnal Equinox on Sept. 22 at 10:49 a.m. EDT. On that date, the hours of daylight and darkness are equal. This marks the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.
"The idea that we are the only intelligent creatures in a cosmos of over a hundred billion galaxies is so preposterous that there are very few astronomers today who would take it seriously."-Arthur C. Clark, author of Space Odyssey 2001
The earliest humans that evolved on Earth, upon looking up at the night sky, must have wondered what was out there in that dazzling panorama. Even in ancient Greece, there were people who believed that worlds other than Earth could exist and that some could even shelter other forms of life. But when a Catholic monk in 1584 made the mistake of claiming that there were "countless suns and countless earths all rotating around their suns," he was accused of heresy by the all-powerful Catholic Church. Following many years of torture in prison, he was burned to death by the Church in 1600 CE. His writings remain on the Vatican's list of forbidden texts, and Giordano Bruno is considered a martyr to scientific truth.
Scientists used to think that the Earth might be unique in our Milky Way Galaxy. But new research has shown that there are undoubtedly billions upon billions of planets with masses similar to Earth encircling stars in our galaxy. These objects are called extrasolar planets or exoplanets. Now, how can tiny, faint planets be detected as they orbit their brilliant stars in the remote reaches of distant space? Several methods have been devised:
Photometric Transit Method: NASA's Kepler Mission spacecraft has been specifically designed to find Earth-size and smaller planets in or near the habitable zone of stars in our region of the Milky Way Galaxy. Even the most powerful telescopes on Earth can't detect planets orbiting distant stars. But the incredibly precise photometers onboard the Kepler spacecraft can detect when a remote star dims periodically. When this happens at regular time intervals, the cause is usually a planet orbiting and blocking a tiny fraction of light each time it crosses in front of the star as seen from Earth (called a transit). From the amount of brightness change we can tell the size of the exoplanet and from the time between transits we can tell the size of the exoplanet's orbit and estimate its temperature.
The Kepler photometer is able to detect a drop in brightness of only 1/100 of 1 percent. This equals sensing the drop in brightness of a car's headlight when a fruitfly crosses in front of it. In order to achieve this degree of precision, the photometer must be placed in space because the atmosphere would create too much distortion. Kepler will continuously and simultaneously monitor the brightness of 100,000 main-sequence stars during its four-year lifetime.
Radial Velocity Method: A star with a planet moves in its own tiny orbit because of the planet's gravity, however small. This causes minor variations in the radial velocity of the parent star with respect to Earth. The newest spectrometers can measure these variations due to the Doppler shift of the parent star's spectral lines. The majority of the exoplanets that have been discovered to date were detected using this method.
Pulsar Timing Method: A pulsar is a rotating neutron star, the small, incredibly dense remnant of a giant star that exploded in a supernova. Pulsars emit radio waves and several other types of electromagnetic waves at extremely regular intervals as they rotate. Slight variations in the timing of these emitted waves are used to track the pulsars' motion through space. Just like a regular star, pulsars move in their own tiny orbits if planets are involved in the system.
This method can detect planets that are much smaller than any other method and was used in the discovery of the first exoplanet ever found. It is estimated that there are about one million pulsars in our Milky Way Galaxy.
Gravitational Microlensing: Einstein predicted that light would change its direction if it passed close to a massive object. Astronomers are now using this fact, that a strong gravitational field bends light, to detect exoplanets. When a planet and its parent star cross in front of a background star, the distant star's light is magnified like it would be by a lens, and it appears brighter for a certain time interval. Observers on Earth see the distant background star become brighter as the lens crosses in front of it. If a planet is orbiting the nearby star, this normally smooth process will be modified in a predictable way.
There are many hundreds of billions of galaxies, each containing billions upon billions of stars, in the known universe. Since planets appear to be a byproduct of star formation, the number of planets that must exist in the universe is beyond human comprehension. These recent findings lead us again and again to the age-old question: do other forms of life exist out there in the remote reaches of the cosmos?
As of Aug. 1, astronomers have discovered 763 exoplanets, using the above procedures. This new-found and seemingly endless supply of exoplanets, and the much larger range of extreme environments on Earth that we now know are teeming with life, greatly increases our chances of finding some type of life beyond our solar system. Undoubtedly, it will just be a matter of time.
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