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

Wednesday, April 25, 2012

Smoke on the Water and Fire in the Sky

Well, I don't know about the smoke on the water part, but last Sunday in Nevada and California there was definitely some fire in the sky.

It's now fairly certain that the explosion reported by so many folks in those two states was a bolide, or a fireball.  Fireballs are large meteors that are generally very bright, and are usually accompanied by a good deal of noise.  Most often they explode in the air - a result of the stress of passing through the Earth's atmosphere.  But what is a bolide, really?

Simply put, it's a shooting star.  A very impressive one.

Shooting stars are not actually stars.  They are meteors - rocks from space which enter the Earth's atmosphere.  Most are extremely tiny - like grains of sand or dust.  The friction caused by all that air rubbing against the rock actually makes the air glow - that's the streak of light we see and call a shooting star.  Tiny dust-fragments never get that far - they disintegrate and are gone before they can heat up enough air for us to see.  Larger chunks make a distinct streak of light, but they actually don't make it very far into our atmosphere either before they too are destroyed.  Big chunks, though, can do some amazing things.

A map showing the location of the April 22nd fireball.  Courtesy

The fireball this weekend was clearly seen in daylight.  When the meteor finally burst apart from the stress, it was pretty close to the ground - maybe about 5 miles up.  If it had been higher up, there would not have been so many reports of loud booms.  Based on information gathered from eye witnesses, it's likely that the meteor which caused all the excitement was about the size of a minivan when it entered the atmosphere.  The energy of the explosion has been estimated at about 3.8 kilotons of TNT, so this was a pretty big deal.  Since it exploded above the ground, there was little actual damage, but it's possible some pieces of the meteor may now rest on the ground.  If these meteorites can be found, they would be quite special, as it is rare to be able to so accurately pinpoint the event that a meteorite came from.

A picture of the Nevada/California fireball of April 22.  Credit: Lisa Warren

So don't forget to keep looking up, even in daylight.  You never know just what you might see!
Carpe noctem et diem!

Wednesday, April 11, 2012

The Planets Will Go On

Hey everyone!

So I am already excited for this Saturday's Star Party and Laser Light Night here at the Virginia Living Museum.  It's going to be awesome, for two reasons.  Number one is that we'll be enjoying a Titanic theme!  This Saturday, April 14, 2012, is the 100th anniversary of the sinking of the Titanic.  We'll be adding a Titanic flair to the night with a special showing of "Night of the Titanic" at 6:30pm.  Then at 7:30pm, we'll have our regularly scheduled "Virginia Skies" but we'll examine the stars of the Northern Atlantic as well and compare them to what we see here in Virginia.  Finally, at 8:30pm, "Laser Magic" features the theme from James Cameron's "Titanic" - Celine Dion's "My Heart Will Go On."  The punned out version of that title which heads up my post tells you the other reason I'm super excited about this Saturday.

Have you looked up in the early evening sky recently?  There are four - count 'em, FOUR! - planets visible to the unaided eye gracing the sky just after sunset.  It's incredible!  If the weather holds and things cooperate, you've got the chance to see all four of these planets through telescopes at the museum this weekend.  And it's free to boot!  How can you beat that?

Looking to the west in the early evening, you can still see Venus and Jupiter decorating the sky after sunset.  Venus is now substantially higher in the sky than Jupiter - the two have been moving apart steadily since their close encounter in March.  Jupiter is lower and fainter than Venus, so look carefully at the western horizon.  Venus will pop right out at you (it is the brightest object in the sky after the Sun and Moon, after all), but look down below Venus for the brilliant jewel of the solar system's largest planet, Jupiter.

Venus above and Jupiter below. Credit: Kevin Jung.

Turning your attention to the East will show you two more planets!  Mars is high in the south-southeast just after sunset, and is a distinctive orange color.  If you turn and compare colors between Mars and Venus, the decidedly orange tinge of Mars becomes very clear.  Mars' unique color comes from rust - the soil on Mars is rich in iron, and over time that iron has combined with oxygen to form rust.  The legendary windstorms of Mars have carried that rusty dust all over the planet, resulting the The Red Planet's characteristic hue.

Look low to the eastern horizon to see the fourth and final planet - golden-yellow Saturn.  If you can join us this Saturday, it will be well worth hanging around until Saturn climbs above our treetops so you can see it through a telescope.  It is quite possibly one of the most amazing things you will ever see!  Even at a distance of roughly a billion miles, the rings are quite distinctive, and with our larger scopes, you might even glimpse a few details in the cloud layers.

Saturn through a moderate-sized telescope.

We'll start setting up our telescopes around sunset (about 7:30-8pm these days) and will continue to observe until about 11:30pm or so.  Observing is free!  Planetarium programs begin at 6:30pm and are $6 for one, $10 for two (members are always half price!).  Make an evening of it and grab dinner in the Wild Side Cafe beginning at 6pm - they'll remain open until 10pm for food, snacks and drinks (both kid-friendly and adult).  It's going to be a "Titanic" night - so come join us!

See you then...
Carpe noctem!