Written by Kelly Herbst, Astronomy Curator for the Virginia Living Museum. Updated every two weeks, more or less.

Wednesday, October 24, 2012

The Ultimate in Star-Power

Did you have trouble with the radio in your car this past Monday?  Did the GPS in your phone suddenly go on the fritz?  If so, then you've experienced the power of the Sun.

The Sun cracked off a wicked little flare which impacted us this past Monday, disrupting some radio and GPS signals.  Many people don't realize just how much the Sun impacts us.  Sure, we all know it gives us light and heat, but did you know it can cause power outages, disrupt communications, and is responsible for the auroras?  There's an entire industry devoted to predicting what the Sun is going to be's called space weather.

The area of the Sun which unleashed Monday's solar flare in several different types of light.  The bright spot on each of the pictures is where the flare originated, except on the magnetogram (there the spot appears dark).  Courtesy NASA.

The Sun is a massive ball of plasma - a highly electrically charged state of matter that has similarities to both gases and liquids.  Material comes streaming out of the Sun almost all the time.  But sometimes, the Sun gets pretty stirred up, and it can unleash an extra burst of material on out into space.  If that material happens to be headed in the direction of Earth, we may experience a variety of effects, from the merely beautiful to the highly dangerous.

The most common effect of solar activity is the Northern Lights, or the Aurora Borealis.  These shimmering colored lights are most easily seen in the extreme north (or, if you're living down under, you can see the Aurora Australis in the extreme south), and occur when charged particles from the Sun strike particles in our atmosphere and excite them.  Eventually the particles give up the extra energy they've received from the Sun and produce a variety of colored lights that seem to dance through the sky.  Auroras are amazingly beautiful, and completely harmless.

Red and green auroras over White Dome Geyser in Yellowstone National Park this month.  Picture by Robert Howell.  Courtesy Astronomy Picture of the Day.

Sometimes, when the Sun is really agitated, those particles come in towards the Earth at speeds sufficient enough to allow them to punch down into the lower atmosphere and affect high-voltage power lines.  Since the particles from the Sun are themselves charged...well...this can do very nasty things to equipment designed to send charged particles in only one direction.  We've been able to trace the causes of several wide-scale blackouts back to the impact of solar material.

The flare that disrupted radio and GPS on Monday was not all that intensive.  Scientists track what happens on the Sun so companies with satellites in orbit and power companies can be made aware of when solar material might be on the way.  We expect an uptick in solar events over the next year, as the Sun reaches the peak of its 11-year activity cycle in 2013.  Want to stay up to date on space weather happenings?  Check out for the latest on solar events.

Until next time, enjoy the sunshine...
Carpe noctem!

Wednesday, October 10, 2012

So What's on Your Mind?

I came to the shocking realization the other day that I've been writing this blog for over a year now.  It certainly hasn't seemed that long to me.

One of the things I was hoping would happen as I began this blog hasn't really materialized yet.  I'd really love to be fielding your questions...talking about the topics that interest you, my readers, the most.  Anyone is welcome to leave a comment on any post - even if your question has nothing to do with the post!  I'll be more than happy to answer your question...and I might even make it the topic for the next blog post.  So please - ask away!

In the hopes of inspiring some new questions, let me share with you the answers to the questions I get asked most frequently.

Who invented the telescope? -OR- Galileo invented the telescope, right?

Actually, Galileo Galilei did many amazing things that advanced our understanding of the solar system we live in, but inventing the telescope was not one of them.  He was the first person to use a telescope for astronomical purposes, turning his simple instrument on the Moon, the Sun, Jupiter, Venus and even Saturn.  But credit for inventing the telescope is generally given to Hans Lippershey, a Dutch lensmaker. 

Hans Lippershey.  Courtesy Wikipedia.

What was that bright thing I saw last night/morning in the east/south/west?

About 99% of the time, the answer to this question is one of the 5 naked-eye visible planets: Mercury, Venus, Mars, Jupiter or Saturn.  Most often, it's Jupiter or Venus, as they are the brightest of these five, with Venus being the brightest object in the sky after the Sun and the Moon.  The planets are generally brighter than the stars near them, and they won't twinkle the way the stars do, making them stand out against the background stars.  These days, Mars is extremely low in the southwest in the early evening.  In the early morning skies, you'll find Jupiter high in the south and Venus mid-way up in the east around sunrise. 

On rare occasions, the answer to this question is Sirius, the brightest star in the nighttime sky.  You'll find Sirius in the winter sky, easily located by following Orion's famous belt to the left.  Sirius will twinkle quite a bit, and it is impressively bright.

Sirius by the Hubble Space Telescope.  The small white dot in the lower left of the image is a tiny white dwarf companion to the main star.  Courtesy NASA.

Where can I buy a quality telescope?

Some camera shops still carry high quality telescopes, but my personal favorite place to purchase observing equipment is online from Orion Telescopes.  They carry an excellent "house" brand, plus the usual players like Meade and Celestron.  Their customer service is excellent, and their prices are quite reasonable.  One word of caution - be wary of purchasing anything manufactured by Meade.  This once-excellent company was bought out several years ago and now offers little or no customer service, and has become increasing difficult to deal with.  Stick with Celestron or Orion's own stuff. 

Where to NOT buy a telescope (especially with the holiday season just around the corner) is any big box store of any kind.  Most "Christmastime" telescopes are cheap, fall apart quickly, and use inferior optical elements.  A good rule of thumb - if the telescope costs less than $150, you are probably going to be disappointed.

When is the best time to see shooting stars in the sky?

Shooting stars are actually meteors - chunks of rock from space coming in to the Earth's atmosphere at high speed.  When they make contact with the Earth's air, the friction generated by the rocks passage causes the air it passes through to glow - making the streak of light we call a shooting star.  While random bits of rock can plunge Earthward at any time, Earth does regularly pass through rocky debris left behind by the regular orbiting of comets.  Such times are called meteor showers, and they are the best times to go out and look for shooting stars. 

The best meteor showers of the year and the rough dates they peak on are:

The Quadrantids  January 4
The Perseids       August 12
The Orionids       October 21
The Leonids        November 17
The Geminids      December 14

I say rough dates because the exact peak date and time changes every year.  In general, the best time to be outside to look for meteors is around 2AM as the combination of the forward motion of the Earth in its orbit and the rotation of the Earth carrying us in the same direction make it more likely that meteors will be visible.  Astronomy is not a hobby for those who like to go to bed early. 

My birthday was yesterday.  Why couldn't I find my sign in the night sky?

Your "sign" is the constellation in which the Sun was located on your birthday.  During the course of the year, the Sun appears in the sky against the background of the zodiac stars, which are part of 12 (13 if you count Ophiuchus, which the ancients really didn't) different constellations.  Today's astrological signs are generally determined by the way the sky looked 6000 years ago, when astrology was getting its start.  In 6000 years, the sky has shifted a fair bit, mostly because very few motions of the solar system actually occur in even numbers of hours or days or months or years.  So what the newspaper says is your "sign" is actually probably not where the Sun really was on the day you were born. 

For example, I was born on November 10.  According to classic astrology, my sun sign is Scorpius the Scorpion.  However, on the actually date I was born...the Sun was located in the constellation Libra the Scales.  6000 years makes a measurable difference in such things.

However, none of that has to do with why you can't find your sun sign constellation in the sky on your birthday.  You can't find it at night, because it isn't there!  By definition your sun sign is in the daytime sky on the day you were born - because it's near where the Sun is on that day.  So if you want to see your sun sign in the sky...wait for 6 months after your birthday.

So what astronomical question have you been longing to ask?  I await your comments eagerly.

Until then,
Carpe noctem!