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Sunday, October 11, 2015

Observing Iridium Flares

On the evening of Wednesday, October 7th, my girlfriend, Christine and I had the pleasure of experiencing a bright Iridium flare at 6:30 pm EDT. Earlier that afternoon, my Insight Observatory Associate, Harry Hammond called me to inform me of a -3 in magnitude Iridium flare that could be seen roughly 62 degrees high and directly due north. Harry's source for the sighting was the website Heaven-Above. Heavens-Above tabulates the altitude and azimuth of each iridium flare event, but you can also use the site to plot a particular flyover against the stars as follows: once you have the list of flares generated by the steps given above, click on a particular spacecraft ("Iridium 53," say), and then click on "Passes." This will give you a list of that spacecraft's passes over your location for the next several days. Click on one of those passes by date, and you can get a star chart showing the spacecraft's quickly changing position among the stars.

Iridium Satellite 54 - Photo by Christoph Lohuis.
Iridium Satellite 54 - Photo by Christoph Lohuis.

My first visual experience of an iridium flare occurred when I was attending the 2006 amateur telescope making convention known as Stellafane that is held annually during mid-summer in Springfield, Vermont. I was relaxing in my lawn chair staring up at the summer Milky Way overhead roughly around midnight. As I was enjoying the clear night sky, I overheard two gentlemen discussing iridium flares. Not knowing much about them myself, I couldn't help but start to listen in on their conversation. As they continued to discuss the topic, one interrupted the other and muttered, "Look right below Sagitta (the constellation of the arrow) In 5, 4, 3, 2, 1..." Immediately after his countdown, a bright burst of light that resembled a star suddenly brightening, then fading, appeared right below the constellation Sagitta as promised.

Of the roughly 3,000 spacecraft in Earth's orbit, just about 100 stand apart: the Iridium communications spacecraft, which skim the uppermost, most rarefied region of the atmosphere (the exosphere) at altitudes around 800 kilometers in six steeply inclined orbital planes (orbits that nearly pass overhead at the North and South Poles). Known as an iridium flare, the glare from these satellites is well known to many astronomers.

How we see Iridium Flares
How we see Iridium Flares

What causes Iridium Flares? Iridium satellites are unique because their flat, shiny, door-sized antenna arrays periodically reflect sunlight toward the ground, causing a brief, but brilliant flares that can momentarily reach an apparent magnitude of –8, brighter than the planet Venus. Also, these flares are predictable and their orbital elements are public information. Thanks to websites such as Heavens-Above, satellite-watching enthusiasts are able to witness these brilliant occurrences. The illustration to the left demonstrates how Iridium Flares are seen from the Earth.
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Saturday, October 10, 2015

Technology Used in Astronomy Today

Astronomy is a topic in science. For most of astronomy, there are scientific instruments in use. These can be telescopes, which have different technologies, and also that of using computers. In this article, we will take a look at the technology used in astronomy today.

Since the dawn of time, man has looked up at the stars in amazement. What were these shimmering lights in the night sky? A torch to light our way? It certainly has been used for farmers, sailors, and many other areas to determine the seasons and other important aspects, however, let us look at the technology used in astronomy.

Hubble Space Telescope in Earth's Orbit.
Hubble Space Telescope in Earth's Orbit.

What was the technology that stone age man and any man or woman today who looks up at the night sky? What is the principle in what is happening when people observe those objects? For certainly the Sun is not as big as my thumb, but actually, a size which could eat up Earth and still be hungry!

The point is simple. The stars and other objects in the sky can be millions of light-years away. As you look at these objects the light travels to meet your eye. As it meets your eye, it goes through the pupil of your eye. This is the technology of man, and to see more, you will need more light entering.

If your pupil was as large as the Earth, our Moon would appear to be like your hands in front of you. This means that the more light we let in, the more we can see, and the bigger it will appear to be.

This is what astronomers and scientists have dedicated themselves to for years. It makes sense. However, the telescopes of today are not using today's technology. Yes, many have some new features, but at the back of it all, they pretty much use 2 different systems.

One of the systems is the famous Galileo's refractor. This works with letting light come through a big lens, and finally through other lenses get focused to meet your eye. What happens here is that you get to see objects far away more magnified. In effect, you have increased the pupil of your eye!

Another system that is widely used is Isaac Newton's system of the telescope. This technology used in astronomy telescopes widely available is that light enters and bounces off a mirror, and comes back up to find another slanted mirror that sends the light through a lens to meet your eye. Again, increasing your pupil in effect, with technology.

There is much more to the technology used in astronomy today. For example, the Hubble Space Telescope and many other astronomical devices. However, one thing that is becoming more common is to utilize a computer which drives the telescope. This has allowed navigation of the night skies to be much easier than it used to be.

Do you want to see what the planets look like? Discover more about astronomy and telescopes and astronomy binoculars by now visiting these links: buy telescopes | Meade telescopes. 

Koz Huseyin

Article Source:  Technology Used in Astronomy Today
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