Upcoming Comets

Now that we’ve had our fill of asteroid action for a while, let’s look forward to comet-carvingsomething a little calmer that’s heading our way this year. Two very bright comets are on the horizon, and one later this year could be the brightest in recorded history. I was fortunate enough to stand in the Arizona desert in 1986 and see Haley’s Comet, and I’m hoping that 2013 will be just as memorable.

Pan-STARRS (Comet C/2011 L4) will be its brightest on March 10 and will hang around until about the middle of April. After swinging around the sun, Pan-STARRS will pass through the constellations Pisces and Andromeda, and will be perfectly positioned for us to see here in the Northern hemisphere. It is expected to be visible to the naked eye and should have an impressive tail.

But the real excitement is building for ISON (Comet C/2012 S1). On Nov. 28, ISON will pass within 680,000 miles of the surface of the sun, much closer than Mercury. Because it is passing so close to the Sun, it is hoped that large quantities of ice and dust will boil off and give us an impressive show. ISON may even be clearly visible during the daylight hours during the days leading up to Christmas. Well, unless the Sun breaks it into pieces first.

Although there are always comets in the sky, most of them pass too far away from the sun to develop large, visible tails. The nuclei of a comet is primarily made up of ice, dust and small rocky particles, and when it gets close to the Sun, the Sun’s heat vaporizes the ice of the comet and blows the ice and dust away with the solar wind – which is why a comet’s tail always points away from the sun.

Fortunately, we haven’t heard anything about either comet passing too close to the Earth for comfort. I mean sure, Jupiter was hit back in 1994 by Comet Shoemaker-Levy, and again in 2009 by another comet that left a bruise about the size of the Pacific Ocean. But hey — we’ve got nothing to worry about, right? (Note: See earlier Bruce Willis entry).

Lynn

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End of the World

The “experts” told us all along that Asteroid 2012 DA14 was not going to collide with earth. Nope. Not a chance. It won’t even disturb our willis4communications satellites as it whizzes through their orbits.

But didn’t DA14 make you just a little nervous? Didn’t you wake up last Thursday and think hey – 17,000 miles is just not that far away! It’s like flying from New York to Sydney and back. And it’s 5,000 miles closer than the satellite that feeds my Direct TV dish.

And then you turn on your computer and see all the images coming from central Russia from an event that NASA described as a “tiny asteroid” that created a blast that was equivalent to 300,000 tons of TNT. Wasn’t this all just a little too close for comfort? But as good Americans, we trust authority, and we trust that someone is looking out for us on a planetary scale, so we go on with our busy day.

But if you do just a little research on your own, your confidence will start to whither. “Asteroid Impact Avoidance” is a good phrase to start with in your search engine. You’ll discover that most articles start with what size asteroid will cause extinction-level damage to our biosphere. Then in the next paragraph or so, you’ll be assured that the threat isn’t any more substantial than it was yesterday, and that modern technology has opened up new options to prevent such an event.

Then you’ll read about all these new “options.” Current strategies seem to fall into two categories: destroy or delay – both will require years of warning in order to design, test and build. Destroy is self explanatory, using nuclear bombs or kinetic impactors to fragment an asteroid into pieces that will either miss the earth or burn up in the atmosphere. Delay strategies sound more promising and involve delaying (or advancing) the arrival of an asteroid by seven minutes (the time it takes the earth to travel the distance of one planetary diameter). Delay strategies include things like gravity tractors, rockets, mass drivers and laser cannons – all of which must be flown near the asteroid in order to push it a little off course.

During all my research, I didn’t find an actual “solution” that is parked on a launch pad and ready to go.  All I found were projects, either existing or planned, that will find and catalog all of the tens of thousands of objects that are big enough to cross Earth’s orbit and do substantial damage. But I even question how successful the last 20 years of cataloging have proven to be, considering that DA14 was discovered by a dentist in Spain only a year ago, and nobody at all saw the Russian asteroid coming. Maybe we need to keep cataloging but also spend some money on a real solution.

Personally, I’d sleep a whole lot better knowing that there was a gravity tractor strapped to an atlas rocket somewhere – tested, gassed up and ready to go. But until then, I guess we’ll all just have to just count on Bruce Willis to save the day. I hope someone has his phone number handy.

Lynn

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A Simple Observing Tool

LittleDipperAs you all know, I’m quite the minimalist when it comes to observing gadgets. I have my trusty observing duffel bag stocked with the basics. I’ve often said that if it doesn’t fit in the bag, I don’t bring it. The basics (to me) are: batteries, rubber bands, red flashlight, star charts, binoculars, towel, pencils, hand and toe warmers, green laser pointer and last but not least, the clipboard.

The clipboard is a key piece of equipment! On it are several important observing tools that help with every session. I have some blank paper and some preprinted observing forms.  Evaluating the conditions of the night sky, namely the ‘seeing’ and the ‘transparency’, is an important part of the night, but it took me awhile to keep them straight! So included on the clipboard is my favorite cheat sheet, the Seeing Conditions chart. (See our Links and Resources page)

Seeing has to do with the condition of the atmosphere itself. Humidity can make the images dance and twinkle, or sometimes they’ll alternately blur and clear. Assigning a number to the current seeing conditions is made easier by the descriptions on the chart. Keep in mind a perfect 10 for seeing conditions is rare! I think the best seeing conditions I’ve seen is a 6 or 7!

Transparency has to do with the limiting magnitude of naked eye objects. In other words, what is the dimmest star you can see with an unaided eye? This can be different from person to person, for example, my night vision not a good as Lynn’s.  The Little Dipper is a good constellation to use, as it has a large range magnitudes contained within it.

As you can see, it ranges from magnitude 2 which is Polaris, to magnitude 6.7. Most people can see down to around magnitude 6 with an unaided eye, in dark sky conditions. You’ll notice that some of the magnitude markers do not have a decimal point. This is how they are supposed to be recorded, so the decimal point is not mistaken for another star.

So- why do we take the time to make this evaluation? Well, most observing
programs require you to record these conditions with your observations. Even if
you aren’t working on an observing program, it’s good practice to make this
observation. I believe it makes me a better observer.

I hope this helps your next observing session! Feel free to print it and make it part of your observing arsenal! We use it every time we go out!

Enjoy!

Amy

A whole new perspective

Orion tilted on his side.
Orion is lying down on the job in the Cayman Islands.

Two weeks ago, I found myself 2000 miles closer to the equator (and 80° F warmer) than I am today. And I understand that this was a tremendous opportunity to take in the night sky from a whole new perspective. But, as Robert Burns put it, “the best laid plans of mice and men often go astray.”

While packing, I spent as much time as I could spare looking around in Stellarium, Sky Safari, and on Google. I even packed my trusty binoculars. But the one clear night in Cayman that I had a chance to look up, I realized I wasn’t nearly ready enough.

It’s cold here in Wisconsin. In fact, it’s 1° F as I’m writing this. And to be perfectly honest, this kind of weather doesn’t inspire me to do a lot of observing. So it was unfortunate that a good grasp of our current sky in Wisconsin was exactly what I needed in order to appreciate what I was seeing in Cayman.

When I looked up from Seven Mile Beach that night, I saw Jupiter and Gemini and Cassiopeia and Auriga. Nope. The sky just didn’t look all that different. But as I continued to get my bearings, once again my old pal Orion saved the day.

When I come home at night this time of year, Orion’s there to greet me. Facing east as I unlock my door, he’s high above me standing on his feet, watching over me. But in Cayman, it was a whole different story. Orion was lying down on the job. Literally. He was nearly horizontal.

That in itself was pretty exciting, but I didn’t want it to be the sum total of my observing session while I was only 450 miles north of the equator. I had high hopes of locating something I couldn’t see from my own backyard.

Two constellations rise on the southern side of the island and are never visible in Wisconsin – Crux (the Southern Cross) and Centaurus. Unfortunately, I was on the northwest side of the island, and no one was willing to drive me south at 3 a.m. (although I did momentarily consider attempting to drive myself on the left side of the road. Probably not a good idea).

But there was one other southern circumpolar constellation available to me there close to the horizon. I found Canopus, the brightest star in Carina. Canopus is a supergiant that is the second brightest star in the night-time sky after Sirius, and has a visual magnitude of -0.72. Although Carina itself was buried in the lights of George Town and the haze that had settled over the ocean, Canopus was high enough and bright enough that there was no doubt. It was white and bright and beautiful.

Next year when I travel down there again, I hope to take more of a perspective with me so that I can appreciate how skewed the sky looks when I’m only 450 miles north of the equator. Plus, I’m gonna drag my son’s butt out of bed and make him drive me to the south side of the island. Crux is a treat I don’t want to miss again!

Lynn

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