The Witch Head Nebula. Click for larger. Image Credit and copyright: APOD and Star Shadows Remote Observatory (Steve Mazlin, Jack Harvey, Rick Gilbert, Teri Smoot, Daniel Verschatse).

This is an Astronomy Picture of the Day selection from last year featuring the Witch Head Nebula.

The Witch Head Nebula is about 1,000 light-years away in the constellation of Orion.  The nebula is known as a reflection nebula because it is illuminated by a nearby star or group of stars, in this case the star is the blue supergiant Rigel.

I was going to use a different version of this nebula for today, but this one is just too good not to use, the bright star Rigel just makes the image all the better.

You can see this image in it’s original context AND links to other scary sights (be very sure to look at the link for the veiled spectre) at APOD.

The original image: A “Witch by Starlight”  Credit & Copyright: Star Shadows Remote Observatory (Steve Mazlin, Jack Harvey, Rick Gilbert, Teri Smoot, Daniel Verschatse).  I tried to image the Witch Head a couple years ago and had very little success so in my book this image isn’t just good, it’s extraordinary.

If you are out and about tonight HAVE FUN AND BE SAFE!

Oh and when you go to the APOD site you can get a larger version so you can put it on your desktop.

The Jewel Box, NGC 4755 from the ESO. Wallpaper links below. Credit the ESO.

The Jewel Box is another name for the open cluster NGC 4755. From the looks of this ESO image, it’s little wonder how English astronomer John Hershel came up with the name when he coined it in the 1830’s.

NGC 4755 is an open cluster, a collection of stars bound loosely by gravity evolved from the same “nursery”, or cloud of dust and gas, so they tend to be similar in age and composition.  Because they are all of the same approximate age, but do vary in mass so they can be at differing life stages.

Higher mass stars will age faster than lower mass stars and sometimes you can see stars in the red giant phase (more mature and nearing the end of their lives) right along with other stars that might only be half way through their lives or even less.

Located about 6400 light-years away, in the constellation of Crux, near the Southern Cross, I know many readers can see it just fine, sadly it’s too far south for me.  No matter, The Jewel Box is stunning and I decided it would make a very nice desktop.  While I was at it I made up a few different sizes, most required some clipping of the image.  Many thanks to the ESO for  sharing this.

Here’s the wallpapers:

Okay.  The solar system is, like, really big, you know?  No, I mean really, really big.  Like, super-massive “epic” big, you know?

Sorry about that.  I couldn’t resist.  Although the wording is annoying, the statement itself is correct.  The solar system is a big place; a lot bigger than some people realize.  Beyond the planets (and poor, demoted Pluto), beyond the Kuiper Belt and the scattered disc, we find the Oort Cloud (rhymes with “fort” and “short”).

NASA/JPL  (Artist’s conception of Kuiper Belt and Oort Cloud)

It’s mind-boggling to think that the tiny little blue rectangle contains the sun, all the planets, and the Kuiper Belt.

Although no confirmed, direct observation of the Oort Cloud has been made, most astronomers believe it to be the source of all long-period comets (like Halley), and of many of the Centaur and Jupiter class comets.  Loosely bound to the solar system, objects in the Oort Cloud are easily influenced by passing stars and the pull of the Milky Way itself.  These shifting gravitational influences will occasionally dislodge an Oort Cloud object and send it shooting into the inner solar system, where we see the objects as comets.

Composed of an inner and outer region, the majority of Oort Cloud objects are believed to be made up of ices such as water, methane, ethane, carbon monoxide, and hydrogen cyanide.  Object 1996 PW is a rocky asteroid believed to originate in the Oort Cloud.

Comet Hale-Bopp; an archetype of Oort Cloud objects:

Image:  Mkfairdpm; English WikiPedia  (some rights reserved) April 1997

Besides long-period comets, only four objects so far are believed to belong to the inner Oort Cloud:  90377 Sedna, 2000 CR105, 2006 SQ372, and 2008 KV42.

While the exact size of the Oort Cloud is unknown, it is believed to extend about 30 trillion km from the sun (18 trillion miles).  That puts its outer boundaries at slightly over three light-years (a light year is exactly 9,460,730,472,580.8 km).  To put some perspective to that distance, after 32 years Voyager I is only 16.596 billion km from the sun.

We talk a lot about the stars.  We’ve been fascinated with those lights in the night sky every since we’ve been physiologically able to look up.  We point telescopes at them; listen to them; marvel at groups of them; study them; and have based a good deal of artwork and poetry on them.  While we’re marveling at distant stars, we sometimes forget that we have a star, a very nice star, sitting only 93 million miles away.

Image:  Lykaestria (some rights reserved)

Bad-mouthed in the recent past as being “insignificant”, scientists now believe that our star (Sol) is brighter than 85% of stars in the Milky Way galaxy (composed mostly of red dwarfs).

Sol is a near-perfect sphere.  Its oblateness (flattening at the poles, bulging at the equator) is estimated at about 9 millionths.  That means there is a difference in diameter between the poles and the equator of only 10 km (6 mi).  The sun makes up 99.86% of the total mass of the entire solar system.  That leaves us sitting on a very small part of the remaining 0.14%.

For most of its life, the sun produces light and heat through a process of nuclear fusion; converting hydrogen to helium.  This is a “joining together” of atoms.  Nuclear power produced on Earth is a process of nuclear fission, which is the “splitting” of atoms.  It takes about 8 minutes and 19 seconds for light to reach the Earth from the sun.  The energy from the sun supports most life on Earth, and always has.  Even the energy stored in fossil fuel was originally converted from sunlight  by photosynthesis.  Recognized since pre-historic times for the enormous impact the sun has upon life on Earth, it was often worshiped as a god.

Image:  STEREO Project, NASA  (October 20, 2009)

The sun’s core temperature is about 13,600,000 Kelvin, and its surface temperature is about 5,800 Kelvin.  Since I’m an American, I did the math to convert those numbers to degrees Fahrenheit:  13,600,000 Kelvin works out to 24,479,540.33 Fahrenheit, and 5,800 Kelvin is 9,980.33 Fahrenheit.  I whine when the temperature goes over 85 degrees Fahrenheit. You’re welcome to correct my math, by the way.

Our star is believed to be about 4.57 billion years old.  It is estimated that in another 5 billion or so years, the sun will expand into a red giant.  But don’t worry, its temperature is slowly increasing, so all liquid water on Earth will probably be boiled away in a billion years and nobody will be around anyway when the sun swallows the Earth.

Now, as far as “doomsday” predictions go; I believe that one.

You know about gamma rays, right?  Those rays that come boiling across billions of light years from rapidly rotating, high-mass stars collapsing into black holes.  We see flashes of gamma rays being emitted in nuclear blasts. We know that if a gamma ray burst from relatively close-up were pointed at the Earth, prospects for the continuation of life become very bleak, very rapidly.  Overall, lifeforms exposed to gamma radiation suffer severe limitations to their likelihood of a future.  All things considered, it seems a pretty good idea to avoid gamma rays.

Well, guess what:  Gamma rays are produced right here on Earth.  Not from radioactive decay (although that certainly does produce gamma rays), not from proximity to collapsing stars.  It happens about 50 times around the globe every day.  Know what causes it?  I’ll give you a hint:

Image:  John R. Southern (some rights reserved)

Lightning.

Unknown until 1994, NASA’s Gerald Fishman discovered Terrestrial Gamma-Ray Flashes (TGFs) by accident, while documenting extraterrestrial gamma ray bursts at Compton Gamma Ray Observatory.

Lasting only about 1 millisecond, but more powerful than the gamma rays emmitted by the sun, the radiation fountains up to be released into space from surprisingly low altitudes.  Not every lightning strike you see is believed to produce gamma rays.  The current theory involves a complicated chain of events called the “Relativistic Runaway Breakdown Theory”.  I don’t know about you, but that sounds rather ominous to me.  “Runaway breakdown”?  After you chew on that for a while, you’ll be excited to learn that scientists now believe that some of the radiation isn’t released to space, but channeled back down to lower altitudes.

Lightning does a lot of strange and interesting things above the clouds.  Sprites, elves, blue jets, and now gamma ray flashes.  Beautiful and awe-inspiring as it is from the Earth, next time you’re in a thunderstorm just think what’s happening on the other side of the clouds… in space.

Red Sprites  Image:  D. Sentman, G. Wescott, Geophysical Institute,
U. Alaska Fairbanks, NASA

NASA has several videos up on YouTube showing lightning from space, like this one,
A little long, but it slows the action down to 5fr per second.   This one shows sprites, and is really interesting.

Now it really is tomorrow, launch is scrubbed for today, maybe tomorrow, but by the looks of the radar that too looks pretty doubtful.

Mission: Ares 1-X

Current Status: Go

Launch Date: Wednesday October 28, 2009, 08:00 EDT maybe….

Odds of Launch: Unknown

Ares 1-X on pad 39B. This image could change as it is a webcam feed from NASA. Image credit: NASA

Tuesday: A slight chance of showers, then a chance of showers and thunderstorms after noon. Partly cloudy, with a high near 84. Southeast wind between 5 and 15 mph, with gusts as high as 25 mph. Chance of precipitation is 50%

I want to see this bad boy to go up and if it doesn’t go up tomorrow I’m likely to miss it.  The Ares 1-X will test NASA’s newest spacecraft and launch vehicle.

The Ares 1-X has a four segment solid rocket motor, and a fifth that is just simulated for this mission, a little scary. The motors provide the power to get this 2,000,000 pound rocket into the air. The test flight will reach an altitude of about 130,000 feet in just two minutes when the upper stage separates, and a total altitude of 150,000 feet! The rocket will attain a speed of Mach 4.76 thanks to 3.3 million pounds of thrust.

Good luck Ares 1-X and NASA!

Go Ares Go!

I will be watching the launch itself on NASA-TV. I will also try to record the launch if it happens (and I don’t mess it up).  Live coverage begins at 05:00 am EDT.

Image Credits: NASA / NOAA