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 OBSERVER. For further information, contact the M.M.M.A.A. at http://www.martzobservatory.org or S.T.A.R.S. at http://www.UpStateAstro.org/stars/stars.html.
If you have an unobstructed view of the western horizon, it may be possible to spot Mercury after sunset during the last half of August, when it emerges from behind the sun. During that time it will be drifting below the much brighter Venus.
Venus appears as the Evening ''Star'' during the second half of the month. Look for it low in the west, soon after sunset.
Mars is also low in the western evening twilight. The Red Planet will sink lower in the sky each night as the month progresses.
Jupiter shines like a bright beacon in the evening southern sky. This is a perfect time to view this enormous planet and its retinue of moons through a small telescope. The planet's cloud belts and the Great Red Spot are usually easy to see. Amateur astronomers discovered a new spot in 2006 and it was named Red Spot Jr.
Saturn is visible low in the west after sunset during the first half of August. It then disappears into the solar glare as it swings behind the sun in relation to Earth.
The Perseid Meteor Shower reaches its peak activity during the early predawn hours Tuesday, Aug. 12. Prime viewing should occur between 1 a.m. and dawn. This is the most popular meteor shower of the year and is usually well worth watching.
LIGHT AS A COSMIC TIME MACHINE
From a really dark observing site in Chautauqua or Warren counties - there are still a few quite good ones left - give your eyes a chance to dark adapt and then look up to the myriad stars that fill the sky. The night sky is our window to an incredibly fascinating universe and the free show goes on every clear night of the year. At the present time, it's impossible for us to visit most of what we see in the night sky, but we know a fair amount about what is out there because the universe reveals an enormous amount of information to us in the form of light energy. And, lucky for us, this information comes to us at light speed, which is 186,000 miles per second or 670 million miles per hour.
However, outer space is incredibly enormous and, even at that speed, it takes light waves 1.3 seconds to get to Earth from the moon, 8.3 minutes to travel the 93 million miles from our sun and 4.3 years for light to reach Earth from the next nearest star. Our Milky Way Galaxy is so huge that it takes light more than 100,000 years to travel from one end to the other. Even though these distances are tremendous, many of the stars and galaxies are bright enough to allow us to not only detect them but to study their light and determine what they are made of, how old they are, etc.
Our Milky Way Galaxy is only one of billions upon billions of other galaxies, each composed of many billions of stars. One of these external galaxies, the Andromeda Galaxy (M31), can be glimpsed with the unaided eye, even though it lies 2.4 million light years away. The light that we detect from this object left that galaxy 2.4 million years ago, so we see it now as it actually was 2.4 million years ago, when humans were still in the early Stone Age. The Andromeda Galaxy is a close neighbor to our Milky Way Galaxy and both are members of the Local Group of galaxies. Most external galaxies are much more distant, with many lying more than 10 to 12 billion light years away. Light waves from those remote galaxies have traveled through space for many billions of years before plunging down our telescope tubes and being detected by either our eyes, film cameras or the newer charge-coupled device cameras. We, therefore, see those objects as they appeared many billions of years ago. The farther away an object is in space, the longer its light takes to get to us and the older that light is when it reaches us. Light truly acts as a cosmic time machine, enabling us to look back into the distant past of our universe.
This ''time machine effect'' occurs in our daily lives but many times we don't notice it. The next time a thunderstorm hits our region, listen for the slower sound of thunder that accompanies a flash of lightning. Although the lightning and thunder do occur at the same time, sound travels much slower than light, so it usually takes a few seconds for the booming sound waves to arrive. If the lightning and thunder arrive nearly simultaneously, the storm is right on top of you. Another example of this time machine effect deals with spacecraft exploring our outer solar system. It takes several hours for radio signals - which travel at the speed of light - to cover the distance from Earth to these spacecraft, so most of their instructions are preprogrammed on the on-board computers.
For the first few hundred thousand years after the Big Bang, the universe was a thick soup of energy and matter. During that period, while the universe was still extremely hot and dense, it was opaque to light energy, not allowing the photons of light to travel. However, the universe continued expanding and cooling and eventually reached a temperature where electrons and protons could combine. At that point, neutral hydrogen was born and the universe became transparent, allowing photons of light to travel freely through space. During the 13.7 billion years since the Big Bang, the expansion of the universe has cooled that early light and stretched its wavelength from ultraviolet to microwave. So, the earliest visible light following the Big Bang has evolved into a diffuse glow of microwaves in all directions.
In 2001, NASA launched the WMAP spacecraft to study minute variations in the temperature of the cosmic microwave background radiation. These measurements reveal the size, age, geometry and matter content of the universe. NASA recently released the results of five years of data collection with this spacecraft. After a comprehensive analysis of this data, astronomers confirmed the 13.7 billion year age of the universe, discovered a sea of neutrinos permeating the background of the universe and placed constraints on the concept of ''inflation'' - the incredible burst of expansion in the first trillionth of a second of the universe.
The WMAP data also showed that the universe is made up of 72.1 percent dark energy, 23.3 percent dark matter and 4.6 percent normal matter such as atoms. So, everything that you see, hear, touch, taste - anything you sense in any way - is less than 5 percent of the entire universe.
