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

Wednesday, April 24, 2013

When One Giant Sets...Another Rises...

Okay, perhaps not as eloquent or well known as the similar saying about doors...but more relevant to the sky right about now.

I do hope you've had the chance to look at Jupiter during this Winter/Spring season.  For some time now, Jupiter has been the dazzling bright white star-like object in the western sky, easily visible as the Sun sets and lingering for a while afterwards.  Well...the lingering is almost over.  Jupiter is now setting perhaps two hours after the Sun, and that time will grow progressively shorter as the days go by.  By the end of next month, Jupiter will be gone from our skies, disappearing into the glare of the Sun.  Long before that happens, it will become very difficult to catch telescopically, being low to the horizon just after sunset.  The season for Jupiter is ending, my friends, and if you haven't yet spent a pleasant evening outdoors, marveling at the wonders of the solar system's largest planet, I urge you to do so without delay.  It would be a shame to miss it.

Jupiter as seen through a small telescope.  The small "stars" seen around the planet are its four largest moons.  Image by Donald Waid. 

Yet even as Jupiter descends into the evening twilight, Saturn also rises.  Climbing up from the eastern horizon around sunset and visible nearly all night long, Saturn is becoming a better and better target for that telescope lingering in your garage or closet.  As Jupiter disappears below the western horizon, Saturn climbs higher into the south, gently gracing the sky with its golden glow.  Saturn appears like a golden-yellow star in the night sky - one that doesn't appear to twinkle.  Planets rarely twinkle, except under the most humid of conditions (think August!), while stars are so distant from us the moving atmosphere of Earth causes them to twinkle even under the best of seeing conditions.  Look to the southeast at 10pm and you'll be able to spot beautiful Saturn quite easily.  It won't be as bright as Jupiter, but if you look tonight, the Moon will be next door to the right, easily guiding your eye to the planet.  And don't worry if you miss it - Saturn will be with us all summer long.  We expect to see quite a lot of it at our summer star parties here at the Virginia Living Museum - so come on out on the second Saturday of the month and join us.  Trust me, there are few sights in the world more amazing than Saturn's rings in a telescope.  Don't miss it.

Saturn seen up close and personal by the Cassini spacecraft.  Don't worry, you'll be able to see the rings without having to travel a billion miles.  Even a quality pair of binoculars will show you the rings of Saturn.  Image courtesy NASA.

So that's my advice to you - go outside and see the planets.  Take a deep breath.  Relax.  And drink in the wonders of the universe around you.

Until next time,
Carpe noctem!

Wednesday, April 10, 2013

UFOs and All That

Greetings, fellow Earthlings!

So, have you been watching television lately?  There seems to be a new fascination with UFO hunting and finding and proving and conspiracy theorizing out there of late.  So I thought I'd write a little about UFOs and what they do...and don't...mean.

When most of us hear the term "UFO" we think aliens!  Spaceships!  Take me to your leader!  Beam me up, Scotty, there's no intelligent life down here!  But actually, UFO stands for something specific: Unidentified Flying Object.  A UFO is nothing more than something flying in the sky that has not yet been positively identified.  It does not mean the purple pod people have come to eat our brains.  Most of what these shows tout as "aliens" are MFOs - Misidentified Flying Objects (thanks, Phil Plait!).  Someone sees something in the sky and misinterprets it as an alien spacecraft.

So what are the most common MFOs?  Here are the top three:

Believe it or not, I get those phone calls here.  Very nice, normal, not crazy people who call me up and explain they saw something very bright, low to the horizon, which appeared to shift and wiggle around, and change color every so often.  Don't panic, I tell them, you've just seen the most common MFO in the world: the planet Venus.  Venus is the brightest object in the sky after the Sun and Moon - it's quite impressive, even in a sky that is not yet dark.  Since Venus orbits the Sun closer in than we do, the planet can never been seen in the skies of Earth more than 45 degrees away from the Sun.  So Venus is frequently seen low to the horizon.  When you look at an object low on the horizon, the light coming from that object has to pass through a lot more air to reach your eyes than a similar object directly overhead.  Well, the moving air of Earth is what causes twinkling - the phenomenon of stars (or planets!) seeming to flash, move, and change color.  So all in all, Venus makes a perfect faux alien spacecraft.

Surely that bright light is an approaching spacecraft!  See the reflection of it in the water!  It can't be a planet!  But it is. It's Venus, seen here in the pre-dawn skies of Earth.  And yes, Venus is so bright, it often shows reflections and casts shadows.  Image courtesy Wikimedia Commons.

It's not just Venus either.  The second brightest planet in the sky, Jupiter, can also fool people into thinking they've seen aliens.  Since Jupiter is an outer planet, it is more likely to be seen high in the sky, mostly eliminating the twinkling effect.  So why do people think it's a spacecraft?  Well, imagine seeing a bright light in the sky.  You don't know what it is, so you grab a pair of binoculars to get a better look.  Suddenly, that single light becomes 5 lights - one big one in the center surrounded by 4 small ones...and it seems to be moving!  Yep, this happens a lot.  Jupiter is surrounded by moons - and the four largest are easily visible in a pair of binoculars...or with modern high-powered TV cameras.  The motion effect is caused by difficulties in holding the binocs or camera steady while viewing.  Sure enough, TV crews sent to check out reports of a UFO have often "confirmed" it with their cameras...only to be told later by local astronomers they were viewing Jupiter.  Oops.

Surely this one is aliens!  Look at the symmetry!  They must be lights on a spacecraft!  Nope, the center bright light is Jupiter and the 4 smaller lights are the giant planet's largest moons, seen here through a powerful camera.  Image courtesy Satellite Imagination.

Last, but certainly not least, is one that most people can't believe could be true.  One of the more common MFOs is...birds.  Really!  Birds!  Especially when seen close to sunset or sunrise flying in formation.  Lighting can really do funny things to your perception of objects in the sky...and a flock of birds flying in formation eerily lit by the Sun and artificial lights can rapidly convince you you're watching the aliens come in for a landing.  Trust me...I've seen the effect.  I was almost convinced...until my "spacecraft" started honking...they were geese.

Okay, this one HAS to be a spacecraft!  Just look at it!  Or... it a bird?  Yeah, it's a blurry bird picture.  Images by Rob S.

So the next time you see something in the sky you can't identify, don't call the guys from the History Channel show - call me.  Or post a comment here on my blog.  I'm only too glad to help turn UFOs into IFOs (Identified Flying Objects).  And if ever we do make contact, it will almost certainly be by radio.  Any alien civilization capable of talking to us must located very far away - too far for a spacecraft to be of any help - or we'd have met them by now.

But we can still hope, right?
Until next time,
Carpe noctem!