31 Oct 2011
Somehow in all the turbulence of our world events and economic disasters and hectic personal lives, an annual event got passed over entirely - again. Jupiter was in opposition and no one even noticed!
It's OK. It's just a few days past and, for all intents and purposes, Jupiter is still in opposition. But what is that, and so what?
Opposition is the term astronomers give to the position of a planet when it is on the exact opposite side of the earth as the sun is. One can draw almost a straight line from sun to earth to a planet in opposition. Because of this, we can see this planet rising in the east at the same time the sun is setting in the west.
And that's exactly what will happen this evening at sunset. Go out in the early evening, soon after sunset, and observe that big bright brother of ours rising brilliantly in the east.
Another way of looking at opposition is the time we pass an outside planet on our inside lane around the sun. Two things result from this.
One is that we are now closest to that planet than ever. In Jupiter's case that means we are a mere 372 million miles away from it. For astronomers that is a wonderful thing. We now see Jupiter as up-close-and-personal as we can from Earth. It's the best time for you who own a telescope to go see Jupiter's parallel weather patterns and, if the conditions are right, the famous Great Red Spot. These are great weeks for espying the Great One.
Another more subtle phenomena that happens around opposition is called retrograde. This is a kooky backwards movement of the planet through the skies, observed by astute sky watchers since ancient times.
Normally a planet would seem to crawl ever so slowly, night after night, week after week, eastward through the background stars. But once a year the planet would slow its trek to a stop, reverse direction for a spell, then turn back again onto its normal path. This strange phenomenon was christened retrograde.
It was eventually explained as nothing more than an illusion resulting from our passing an outer planet from our closer, faster orbit. This makes it appear that the slower planet is temporarily moving backwards.
Well, Jupiter is in retrograde now. The more patient readers here may notice Jupiter over the next couple months creeping westward through the faint background stars, then switching direction once we are in the new year.
Go out tonight and catch a glimpse of the great gas giant, and if time and schedule allow for the next months, follow its dance through the stars in the skies above.
17 Oct 2011
What a beautiful universe we live in - an absolutely stunningly beautiful place. But what we see is just an imperceptibly small amount of all the information blazing out of those stars and galaxies and planets.
How can that be? And how can we know more? First, some insight on sight.
We can see because tiny packets of energy called photons enter our eyes and get absorbed by the retina of our eyeball. The retina translates this energy into electrical impulses and sends it all to our brain which puts it all together into a pretty picture. Hence sight.
But those photons that we see are just a small fraction of all the photons around us. There are photons with more energy than those our eyes can perceive and photons with less energy. We are literally blind to those.
They have familiar names, like X-rays and gamma rays, ultraviolet and radio waves. They are all the same animal, just with different amounts of energy.
And the universe is flooded with the whole zoo of photons, not just the visible critters. Then how can we "see" them, and what can they tell us?
Very clever people over the last hundred years have invented instruments which can collect and focus all these different photons, just like the telescopes we are familiar with collect and focus the visible light that we enjoy so much. Scientists tell the instruments to then translate those invisible energies into visible images allowing us to effectively "see" in wavelengths our eyes were not designed to pick up.
For example, radio telescopes, which are not much more than giant dishes aimed at the sky, can collect radio waves, which have the lowest energies of the photon family. Special computers are commanded to plot what they see on a chart in visible wavelengths so we can see it, too. This allows us to "see" areas in space where cool, invisible clouds of gases are chilling out, perhaps waiting to turn into stars.
Infrared telescopes can actually help us see inside great clouds of dust called nebulae. Since infrared photons can travel through dust, an infrared telescope can help us see the newborn stars hidden inside nebulae, like the famous Orion Nebula.
Ultraviolet scopes help us see the turbulent ultraviolet violence on the sun. X-ray telescopes can help us see the massive disruption near a black hole or the unimaginably large amount of energy pouring from a blue giant.
Gamma ray scopes can point out where notorious "gamma ray bursts" signal the extreme death of a giant star.
Without these extra eyes on the skies we would have nothing but the beauty we see, which is amazing in itself. But capturing all these extra kinds of photons gives us a clearer understanding of the universe we can see, and a view into the universe we cannot.
03 Oct 2011
I honestly didn't see this day coming, a day when I could say that a person could hold a phone up to the skies to find out what was up there. Today's column is about an app I use for my iPhone and iPad called Star Walk. I don't often write about applications but I feel that this is something readers of this column can use, and it is dirt cheap.
Star Walk, an app by Vito Technology, allows any layperson to navigate the skies above, day or night, without having to spend a couple hundred bucks to do it.
Star Walk opens up with what is called Sky Live, a beautifully illustrated summary of information about the day's rising and setting of the sun, the phases of the moon, and the location of the naked-eye planets.
But the beauty doesn't end there by any means. The next window takes you right to the sky. When I first got the app I just used the touch screen to move around the heavens and see the different constellations and stars and planets, a virtual star chart of the entire sky.
But when you hold your device up, the GPS and gyroscopes kick in to make your local skies alive. Suddenly wherever you point the device, there is on your screen in full color, the very sky in front of you, illustrated and labeled. (And you can see even the skies below the horizon since Star Walk is not limited to the visible sky.)
That will keep you busy for long enough, but there's more. Tapping on a constellation or star or other point of interest will allow you to get information on that object. Using the search button will help you find all kinds of objects by directing you to them with an on-screen arrow. Want to know where Cygnus the Swan is? Enter it and Star Walk takes you there.
Other handy extras include a night vision mode to make it easier for your eyes to go between screen and dark sky. You can follow various satellites. A sliding clock can take your sky forward and backward in time. There is an adjustable Visual Magnitude bar for better representing how dark - or how light-polluted - your sky might be.
The latest version has a gift for us nerdy backyard astronomers - a full spectrum scroll. Here you can "see" how the heavens look in all kinds of wavelengths from gamma ray all the way down to radio waves.
The bad news for some readers is that Star Walk is only available for the iPhone and iPad. (The iPad version is stunning.) The good news is that it's just $3 for the iPhone, $5 for the iPad. You cannot beat that price.
It is available at the iTunes Store. Go get it and start exploring!