If you have been thinking about buying a solar filter for your scope but have been putting it off, you had better order it now. The Sun is becoming very active with large groups of sunspots moving across its surface every day. Late in September a series of minor to moderate geomagnetic storms have triggered auroras along the northern tier of the states and may have affected some power systems in the northern latitudes. This recent increase in geomagnetic activity is just a sampling of more to come as the Sun approaches the maximum of its 11-year sunspot cycle in mid 2000. The action continued in October, as the sun erupted three times from October 12 to October 13, sending coronal mass ejections away from the direction of the earth. These ejections can carry up to 10 billion tons of plasma traveling at speeds as high as 2000 km/s. When they collide directly with Earth they can excite geomagnetic storms causing satellite communication failures and in extreme cases, induce electric currents in the Earth and oceans that can interfere with or even damage electric power transmission equipment. The good news is that increased levels of solar activity will likely trigger dazzling auroral displays at mid-latitudes. The latest Solar Flare Alert came on October 14 where a small X-class solar flare erupted from a group of active sunspots. At that time this group of sunspots was nearing the central meridian of the Sun. Forcasters were predicting additional fare activity for the next 4-6 days and may result in associated coronal mass ejection trajectories that are pointed to Earth. At that time the possibility of intensified levels of geomagnetic and auroral activity were high. This region should provide amateur solar observers to observe dynamic changes in sunspot activity. Those with hydrogen alpha filters should be able to see subflares, point brightening, and surging should be possible. Now is the time to get that solar filter and start observing the active Sun. If you would like to get Solar Alerts contact: sun-earth@skypub.com and in the body of your e-mail type subscribe. Also check out the following sites for more solar information and real time images of the sun: http//solar.uleth.ca/swarm and http://solar.uleth.ca/sunnow. At the last site images of the Sun are updated once every minute when the Sun is above the horizon. Also with the increased activity of the Sun solar filters are going to be high in demand, so don't wait too long or you might have to wait for a back order. Good sources are Thousand Oaks, Orion and Astronomics.

UPDATE: ASTRO CORNER

The sun just keeps on erupting. Since the last report more solar flare alerts have been issued. On Oct. 21 a strong disturbance had been detected by the ACE spacecraft upstream of the Earth. This disturbance was expected to impact the Earth's magnetosphere. There was a good chance for auroral activity in the northern states. It is likely that this disturbance is the compressed shock front of a correlating interaction region that is being driven by the high-speed solar wind stream of a well-placed and recurrent solar coronal hole. I viewed the sun Thursday and it is covered with several large groups of sunspots. This sunspots are where flares can erupt any minute and send plasma to earth. To keep alert of this activity visit www.skypub.com/news/astroalert.html and follow the instructions.

MERCURY VISITS THE SUN

If that's not enough activity for the Sun, it's also going to be visited by Mercury, adding an extra spot on its surface to confuse you. What will be the last transit of Mercury or any transit of any kind until May 11, 2391, yea that's correct 2391, on November 15 you have the opportunity to view this sight that few before or after will have. You don't want to miss it. On November 15 between 3-5 p.m. CST depending on your location, Mercury will enter the solar limb as a round black dot roughly a third of the way from the north around to the East Point of the solar limb. Use as high power as possible when observing and always use a solar filter. You can get a customized prediction for your location by sending a self-address stamped envelope and give your latitude and longitude of your observing site to the nearest 0.01 degree or to the nearest arc minute to John Westfall, P.O Box 16131, San Francisco, CA 94116. The closest cities I have seen for predictions are St. Louis at 1st contact 3:11p.m., Denver - 2:11p.m. and Chicago 4:11p.m. Check out Sky and Telescope November issue pages 108-112 for more details. Again you are very privileged to be able to view this as no one will be able to see another transit until the year 2391! Don't miss it.

AURORA ALERT - ASTRO CORNER

Reports have been streaming in from the northern states of beautiful and amazing aurora observations just in the last few days. In New Jersey, green curtains to the north, occasionally intense diffuse red glow to NE sky lit by 90% moon. Auroras are very rare at this location. In South Dakota an observer writes; "... amazing I was awoke at 1a.m., couldn't sleep, sky was a bright green, aurora extended almost directly overhead. Almost entire North horizon, 1st beams shooting up and balls of light shooting up, then curtains of light like pouring over an upside down water fall, one burst of red light, very bright green, white prevalent lines in beams, ball fuzzy bomb explosions flying across the sky." And in Minnesota; "I have lived here 40 years. I have never seen such bright aurora. It also went more than 90 degrees overhead all the way from the horizon and all the way east to west. I live near a large city, in the suburbs and it was very high and visible even with a nearly full moon. A truly impressive display." And as far south as Colorado; red and green curtains were observed. Many of the northern state observers felt that many southern states should be able to see this auroras as high in the sky as they reached, so you might want to start looking after midnight toward the northern horizon.

That's it for my Astro Corner this month, hope to see everyone for the Leonid Shower November 17-18.

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October SKY FORUM

By Don Cole

This month let us move a (little) further out into the realm of space and get into the domain of the galaxies in particular the Milky Way Galaxy. The term Galaxy, brings to mind a massive ensemble of hundreds of millions of stars, all gravitationally interacting, and orbiting about a common center. All the stars visible to the unaided eye from earth belong to the earth's galaxy, the Milky Way. The sun with its associated planets is just one star in this galaxy. Besides stars and planets, galaxies contain clusters of stars; atomic hydrogen gas; molecular hydrogen; complex molecules composed of hydrogen, nitrogen, carbon, and silicon, among others; along with X-rays, Gamma rays, cosmic rays, along with many other phenomena, possibly even including (Billy-rays), OOPS sorry about that.

Early History of the Study of Galaxies:

A Persian astronomer, al-Sufi (903-36), is credited with first describing the spiral galaxy seen in the constellation Andromeda. By the middle of the 18th century, only three galaxies had been identified. In 1780, the French astronomer Charles Messier (1730-1817) published a list that included 32 galaxies. These galaxies are now identified by their Messier (M) numbers; the Andromeda galaxy, for example, is known among astronomers as M31.

Thousands of galaxies were identified and cataloged by the British astronomers Sir William and Caroline Herschel and Sir John Herschel, during the early part of the 19th century. Since 1900 galaxies have been discovered in large numbers first by photographic searches and by images from HST (Hubble Space Telescope). Galaxies at enormous distances from earth appear so tiny on a photograph that they can hardly be distinguished from stars. The largest known galaxy has about 13 times as many stars as the Milky Way.

In 1912 the American astronomer Vesto M. Slipher (1875-1969), working at the Lowell Observatory in Arizona, discovered that the lines in the spectrum of all galaxies were shifted toward the red spectral region. This was interpreted by the American astronomer Edwin Hubble as evidence that all galaxies are moving away from one another and led to the conclusion that the universe is expanding. It is not known if the universe will continue to expand or if it contains sufficient matter to slow down the galaxies gravitationally so they will eventually begin contracting to the point from which they arose. This is one of the driving forces and major problems behind the science known as Cosmology.

Classification of Galaxies:

When viewed or photographed with a large telescope, only the nearest galaxies exhibit individual stars. For most galaxies, only the combined light of all the stars can be detected. Galaxies exhibit a variety of forms. Some have an overall globular shape with a bright nucleus surrounded by a luminous structureless disk. Such galaxies, called (ELLIPTICALS), contain a population of old stars, usually with little apparent gas or dust, and few newly formed stars. Elliptical galaxies come in a vast range of sizes, from giant to dwarf.

In contrast, (SPIRAL GALAXIES) are flattened disk systems containing not only old stars, but also large populations of young stars, large amounts of gas and dust, and molecular clouds that are the birthplace of stars. The HST image of the "Birth-Place of Stars" in the Eagle Nebula, appears to bear this out according to the most recent theories. Often the regions containing bright young stars and gas clouds are arranged in long spiral arms that can be observed to wind around the galaxy. Generally a (HALO of faint older stars surrounds the disk; a smaller (NUCLEAR BULGE) often exists, emitting two jets of energetic matter in opposite directions.

Other disk-like galaxies, with no overall spiral form, are classified as (IRREGULARS). These galaxies also have large amounts of gas, dust, and young stars, but no arrangement of a spiral arm formation. They are most often located near the larger galaxies and their appearance is probably the result of a tidal encounter with the more massive galaxy, by either passing close to or actually going through another Galaxy. Some extremely (PECULIAR) galaxies are located in close groups of two or three, and their tidal interactions may probably have caused distortions of spiral arms, producing warped disks and long streamer tails.

(QUASARS) are objects that appear to be stellar or almost stellar, but their enormous red shifts identify them as objects that are at very large distances. They are probably closely related to radio galaxies and to BL Lacertae objects.

Determination of Extragalactic Distances:

As you view a galaxy with a telescope, it is impossible to gauge its distance, as it may be a gigantic bright galaxy at a large distance or a smaller fainter one closer to earth. Astronomers (estimate) distances by comparing the brightness or sizes of objects in the unknown galaxy with those in the earth's galaxy. The brightest stars, Type (1) one supernovas, star clusters, and gas clouds have been used for this purpose. Cepheid variables, stars the brightness of which varies periodically, are especially valuable because the period of pulsation is related to the intrinsic brightness of the star. By observing periodicity, the true brightness can be computed and compared with the apparent brightness; distance can then be (inferred). Recently astronomers have learned that the speed of the stars as they orbit the center of their galaxy depends on the intrinsic brightness and mass of that galaxy. Rapidly rotating galaxies are extremely luminous; slowly rotating ones are intrinsically faint. If the orbital velocities of stars in a galaxy can be determined, then the distance of that galaxy can be inferred.

Distribution of Galaxies:

Galaxies are generally not isolated in space but are often members of small or moderate-sized groups, which in turn form large clusters of galaxies. The earth's galaxy is one of a small group of around 31 confirmed galaxies that most astronomers call the (LOCAL GROUP). The earth's galaxy and the Andromeda galaxy are the two largest members, each with a million stars. The Large, Small, and Mini Magellanic Clouds are nearby halo satellite galaxies, but each is small and faint, with about 100 million stars.

The nearest cluster is the Virgo cluster; the Local Group is an outlying member of the cluster, which contains thousands of galaxies of all types. They all share a common direction of motion, the cause of which might be a supercluster hidden from view by our own galaxy, since superclusters up to 300 million light-years across are known. Some theorists suggest instead that a cosmic "string" a one-dimensional flaw in the fabric of space-time, could be the cause.

Overall, the distribution of clusters and superclusters in the universe is not uniform. Instead, superclusters of tens of thousands of galaxies are arranged in long, stringy, lace-like filaments, arranged around large voids. The Great Wall, a galactic filament discovered in 1989, stretches across more than half a billion light-years of space. Cosmologists theorize that "dark matter," a hypothetical material that neither radiates nor reflects light, has sufficient mass to generate the gravitational fields responsible for the heterogeneous structure of the universe.

The most distant galaxies known, near the edge of the observable universe, are faint blue objects called "blue fuzzies" because of their appearance on photographic plates. The images were obtained by aiming a telescope at apparently blank regions of the sky and using a solid-state charge-coupled detector (CCD) to gather the very faint light, then processing the images by means of a computer. The galaxies, moving away from earth at about 88 percent of the speed of light, may have been formed about 2 billion years after the origin of the universe.

Rotation of Spiral Galaxies:

Stars and gas clouds orbit about the center of their galaxy. Orbital periods are usually more than 100 million years. These motions are studied by measuring the positions of lines in the galaxy spectra. In spiral galaxies, the stars move in circular orbits, with velocities that increase with increasing distances from the center. At the edges of spiral disks, velocities of 300 km/sec (about 185 mi/sec) have been measured at distances as great as 150,000 light-years.