Mars Opposition 2005

Hi Skywonderers!

Getting ready for Halloween? Well it looks like the Great Pumpkin really is coming this time!

This weekend Mars will come closer to Earth than it will again for another 13 years. Mars will be as close about 43 million miles away on October 30th, 2005, just in time for Halloween.

Whenever an outer planet, one that is further from the Sun than earth, is opposite the Sun as viewed from earth, it is said to be "in opposition" which is a time when that planet is really close to earth.

Mars is in opposition with earth every 26 months, or roughly every two years. The last opposition, on August 27th 2003, was truly a historic one with Mars being only 35 million miles from earth. Mars will not be this close to earth again until August 28th, 2287!

Learn more about Mars opposition from the NASA Mars Exploration Page.

Mars will be easy to spot in the sky this year, as it is very large and bright and has an orange "pumpkin" color to it! This "Great Pumpkin" will rise in the east just after sunset, travel across sky all night long, then set just before sunrise for many nights near Halloween this year!


Yes, the closest technically is on October 30th, but we can't help but celebrate the Great Pumpkin's arrival finally!



Trick or Treat!

Dan

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See the Shuttle and ISS From Your Backyard!

Want to see the Space Shuttle Discovery undocking from the International Space Station from your own backyard?

Currently the shuttle is docked to the ISS, but it is planning to undock and separate the space station early Sunday morning, August 7th.

Within several hours of this separation people in central Texas (YOU AUSTIN), south Florida and Louisiana will be able to see two starlike objects, the shuttle and ISS, travelling across the early morning sky!

See the NASA Science Space article here: http://science.nasa.gov/headlines/y2005/04aug_sightings.htm?list133024

To find the space shuttle and other objects in the sky above your location, vist the Heaven's-Above website at: http://www.heavens-above.com.

Good Night!

Dan

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Subscribe to SkyWonders.com Email List!

Want to know when an update has been made to SkyWonders.com? Subscribe to the email list by sending an email to:

skywonders_owner@skywonders.com

with the subject "subscribe" and it's done!

Dan

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More on the 10th planet discovery

A newer, better article related to this weeks' 10th planet discovery by CalTech astronomers was published on Sky and Telescope's website yesterday: http://skyandtelescope.com/news/article_1560_1.asp

When I first heard this news yesterday I initially didn't think much of it since :

1) Astronomers have already found a few large Kuiper Belt objects (objects in the ring of debris at the very outskirts of our Solar System)
2) Astronomers keep finding extra-solar planets (outside of our solar system)

But this new discovery is different than those discoveries because it is bigger than Pluto, making it more likely to receive official planetary status by the International Astronomical Union, the international body that decides the names of planets among other things. The planet's name is still waiting a response from the IAU, but is known informally as "Lila" by its discoverers. Mike Brown, one of the discoverers, says as much on his website: 2003UB313 Discovery page

Incidentally, 2003 EB313 (Lila) was officially discovered A DAY AFTER another large Kuiper Belt Object (KPO) that was officially discovered by astronomers in Spain: http://www.iaa.es/%7Eortiz/brighttno.html. This object, officially called 2003 EL61, has not received as much press as Lila, because it was smaller than Pluto.

The CalTech astronomers who discovered Lila technically also found 2003 EL61 (they called it Santa) in their data BEFORE it was discovered by the Spanish astronomers but waited too long to publish their discovery and so did not get the official discovery credit: Mike Brown's 2003 EL61 Discovery page.

So how do all the Kuiper Belt Objects discovered thus far stack up in size?

These images may help:

Good Night!

Dan

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Remember Columbia: NASA Returns To Space

In 3 days the shuttle Discovery will lift off from launch pad 39-B at Cape Kennedy, signifying NASA's return to space after a more than a 2 year hiatus after the Columbia tragedy of February 1, 2003.

As part of remembering that tragedy, I thought I would share a really great article entitled The Problem With Houston that eloquently describes the events that led to the disaster.

Although this article was initially published in Atlantic Monthly, it can be found online in two parts on the Guardian Unlimited website here:

Part 1: http://www.guardian.co.uk/columbia/story/0,12845,1120962,00.html
Part 2: http://observer.guardian.co.uk/magazine/story/0,11913,1119849,00.html

I strongly encourage you to read the above article as it details the failure of the NASA bureacracy to react to the concerns of a team of low-level engineers to the video of a large piece of foam hitting the left wing of Columbia on takeoff. It is a good illustration into the effect of organizational culture on good engineering judgement and analysis. It is now known that the foam could have caused a 16-inch hole in the leading edge tiles of Columbia's left wing.

Results from investigation of Columbia tragedy: http://www.npr.org/news/specials/shuttle/

Pictures of Columbia disaster: http://www.guardian.co.uk/gall/0,8542,888237,00.html

See complete coverage online of the launch of Discovery on July 13, 2005 at: http://www.nasa.gov/

Good night!

Dan

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Light Pollution World Atlas

Are you curious as to how dark your sky is? Or where to go near you for really dark sky?

In 2000, ISTIL, the Light Pollution Science and Technology Institute in Italy, generated The First World Atlas of the zenith artificial night sky brightness at sea level. This atlas was generated using satellite data and modeling of light propogation in the atmosphere.

The technique used to generate this Light Pollution World Atlas is detailed in a paper written in the Monthly Notices of the Royal Astronomical Society. By comparing this Atlas to detailed population density maps, the paper reveals that 2/3 of the world's population and 99% of the US population (excluding Hawaii and Alaska) and 99% of the European Union's population live in light polluted skies. In addition, 20% of the world's populatoin, 67% of that of the US and 50% of that of the EU can no longer can see the Milky Way.

Those are tragic statistics indeed.

Here is the Light Pollution World Atlas :


Notice how the US, the EU and Japan are the biggest light pollution offenders, which by no coincidence are the most industrialized regions of the world.

The World Atlas is available at the ISTIL website as a 200MB TIFF image that you can then use to zoom in to your particular area of the world.

Someone has done this already for Texas: http://personalpages.utsi.com/~kgl/Texas_LP_Maps.html

The colors in the light pollution maps correspond to the ratio between artificial sky brightness and the natural sky brightness of:

• Black <0.01
• Dark Gray 0.01 - 0.11
  
• Blue 0.11 - 0.33
  
• Green 0.33 - 1
  
• Yellow 1 - 3
• Orange 3 - 9
• Red 9 - 27
• White > 27

Don't get discouraged, however, as I happen to live at the edge between red and orange and still am able to see lots of stars, although every year it gets worse.

One thing to note is that this map is for ZENITH light pollution, meaning straight up from where you are. If you have a large city to the North (as I do), then your Northern skies will be significantly less than your zenith value.

If you're looking for dark skies, you'll have to consider how dark you really want it. And even if the area you choose is considered Dark Gray, be sure you don' t have any White areas too close or you will lose that part of your non-zenith sky.

Good (dark and clear) night!

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Mars Lander Found??

It is possible that the Mars Polar Lander has been finally found?

It appears that upon reexamining images taken in 1999 and 2000 from the Mars Orbital Camera aboard the Mars Global Surveyor, planetary scientist Michael Malin may have discovered what appears to be impact marks and the deployed parachute from the MPL spacecraft lost in December 1999.

Here are the complete articles from the web:

http://skyandtelescope.com/news/article_1509_1.asp

http://www.cnn.com/2005/TECH/space/05/06/mars.lander.ap/index.html

Dan

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Partial Eclipse on Friday!

This Friday, April 8th, North America is in for a celestial treat that can actually be enjoyed during the day!

The moon will partially eclipse the sun for most of North America between 4pm and 6pm CDT.

NASA Science Article about the April 8th Partial Solar Eclipse



You don't need fancy equipment to safely view a solar eclipse, partial or total. You can easily build a pinhole camera that can project an image of the sun that can be viewed directly.


(image courtesy of ECLIPSE by Bryan Brewer)

If you don't want to go to that much trouble, just stand under a leafy tree!

Trust me!

If you pay careful attention to a tree's shadow during a partial eclipse you'll notice that the normally round "sun specks" in the shadow will have a "bite" missing! The gaps in the leaves of the tree will act a bit like the pin-hole camera above and project an image of the sun on the ground that you can view safely!

This is not something unusual to eclipse time -- the image of the sun is often projected through "pin-holes" all around us, we only especially notice when the round projections have a "bite" missing.

A similar effect occurs if you close the blinds on a window facing a solar eclipse: the holes in the blinds will project the eclipse!

Here's a Sky and Telescope article about the upcoming eclipse: http://skyandtelescope.com/observing/objects/eclipses/article_1445_1.asp.

Enjoy!

Dan

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Sky Cartoons!

Ok, so not everything has to be so serious.

Here are some really nice astronomy-related cartoons that you can enjoy!

The first is Jack Horkheimer's Sky Gazer cartoon archive, which has a new cartoon every month.

The second is the SkyWise archive, brought to you by Jay Ryan. His cartoons were featured in Sky and Telescope magazine from June, 1997 to December, 2001.

Just for grins, here's the Sky Gazer for February, 2005:


Good Night!

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How Huygens Almost Wasn't

Does everyone remember the Huygens space probe which successfully landed on Saturn's moon Titan on January 14, 2005?

(If not, read this: http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=530)

The Huygens probe successfully returned multiple images of the surface of this mysterious methane-covered moon which has been compared to a primordial earth.

What is not commonly known is how the Huygens probe came dangerously close to being a complete scientific failure!

Two critical mission errors related to Huygens almost prevented any data being recovered from the landing mission. It was only due to some engineering ingenuity, perseverance, and some luck that we have any data at all from the atmosphere and surface of Titan!

1. The first problem involved the radio communications link between the Huygens spaceprobe and the Cassini orbiter.

When the orbiter-lander mission was launched in October, 1997, extensive electrical and radio tests had been performed to ensure communication integrity between the spacecraft, both connected and separated.

However, this was a very basic test. A more complete full-scale communications test that simulated the actual flight conditions and telemetric data to be handled by the spacecraft had NOT been performed. This more elaborate kind of test was rejected for budgetary reasons, since it would have required disassembly and recertification of the components for spaceflight.

The lack of this comprehensive test bothered one of ESA's ground operations managers to the point that he asked one of ESA's global ground antenna engineers to send a special signal from earth to Cassini, one that simulating the type of signal Huygens would send if it were landing on Titan. What they found was astounding: The data was corrupted depending on the amount of Doppler shift (an effect where the frequency of a wave is changed due to the relative velocities of the wave's source to its recipient).

The effect of Doppler shift was critical: the planned flight plan meant that the Cassini orbiter would be traveling at 5.5 km/s relative to the probe at the time when data would be transmitted. The radio hardware used by the spacecraft had been designed to compensate for the Doppler effect, BUT ONLY for the carrier signal and not for the digital to analog encoding scheme used for the data carried on this signal.

Thanks to this finding BEFORE landing on Titan, the flight plan was changed so that the Doppler effect would be minimized. This changed the Titan landing time frame from November, 2004 to January, 2005.

Read a more comprehensive article related to this discovery that appeared in IEEE Spectrum: http://www.spectrum.ieee.org/WEBONLY/publicfeature/oct04/1004titan.html

See the NASA/ESA press release after discovering the problem in 2001: http://www.jpl.nasa.gov/releases/2001/cassini_010629.html

On to the second major mission error...

2. Half of the data sent from Huygens to Cassini during the landing never made it.

Cassini has two data channels meant to receive data from Huygens, but before the critical moment of the landing transmission one of them was simply not turned on, the command not being sent from earth!

http://spaceflightnow.com/cassini/050115science.html

Fortunately, several of the largest radio telescopes on earth were pointed at Huygens at the moment of the transmission as part of a wind speed experiment. Cassini, combined with these earth-bound radio telescopes, was meant to measure different wind velocities of Titan's atmosphere by measuring the Doppler shift of the carrier signal (Cassini of course would have had to account also for its own high velocity).

After discovering that half of the Cassini data was missing, engineers decided it might be possible to reconstruct at least part of the missing Cassini data using the radio signals gathered directly from earth. The radio telescopes' data was not only able to provide the needed information about Titan's atmospheric wind velocity and direction, but also gave the first indication of the health of the Huygens spacecraft during landing. In addition, scientists were able to gather information as to the precise location of the lander on Titan using the earth data.

http://www.nrao.edu/pr/2005/titanwinds/


So what do we learn from these flaws in the Cassini-Huygens mission?

That to err is human, but with some ingenuity we can persevere.

Good Night!

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Get Ready for World Jump Day!

Want to drive the earth out of its orbit?? Well here's your chance!

There's a web-driven initiative to try to deviate the earth from its orbit depending on how many people participate: http://www.worldjumpday.org/

Basically, these folks want to use the internet to help coordinate how many people jump simultaneously to provide enough force to push the earth out of its orbit on July 20, 2006

The entire theory of pushing the earth out of its orbit via simultaneous jumping, in my opinion, is UTTERLY LUDICROUS!

Why, you ask?

Oh, I can't even begin to name the reasons. Oh, yes I can!

First of all, I guess it depends on how you define "out of its orbit". Technically, the so-called "butterfly flapping its wings" does cause an infinitely small force on the earth, just like my typing right now pushes on the keyboard which pushes on the desk which pushes on the floor ad infinitum.

So the amount you push the earth out of its orbit has to be measurable.

Basically, if you do the math you'll find out that all people on earth jumping at the same time would have about 2% of the effect of pushing on the earth as a modern H-bomb.

That's assuming everyone jumps exactly the same height and the same way and exactly at the same time. And on the same side of the earth, mind you, otherwise you get people in Australia canceling out people in Canada!

Since we know that many H-bombs have been tested on earth, in modern times, and that the earth hasn't yet shifted from its orbit, the idea of a bunch of people managing it on one specific day is simply impossible.

It also depends on what you mean by "its orbit"! The earth does not exactly trace its exact path every year due to a significant amount of gravitation pull by its nearest neighbors, namely Jupiter, Mars, Venus, and the Moon.

Don't credit me here: the physics here I got here come from this website with the best explanation: Ask Mad Physics article on World Jump Day. Or read the discussion going on on kottke.org.

It just goes to show once again how people can take advantage of how the general public forgets to apply everyday physics.

Two examples that illustrates this forgetfulness:

How deep does water have to be for your car to float?? About 24 inches, or 2 feet. See here and here.

Don't even get me started when it comes to a car trying to beat a train at a railroad crossing! When a 15000 ton train is bearing down on you and your 1-ton vehicle, you will soon realize how abundantly important physics becomes!

Good Night!

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