Author Archives: RC Davison

The Majesty of Saturn

Posted on by
Reply

The Cassini spacecraft has been orbiting Saturn since June 30, 2004 and has returned many amazing images of this majestic planet. On July 19, 2013 Cassini took a series of images over a period of more than four hours that resulted in the image you see here. (Click on the picture for a larger image.)

Saturn small

Saturn as taken by Cassini on July 19, 2013

The planet is back-lit by the Sun and shows off its spectacular ring system in great detail. From the finely etched inner rings to the diaphanous outer “E” ring, which is created by the ice geysers on Saturn’s moon Enceladus. Enceladus can be seen as the bright dot embedded in the ring on the left side of the image. This ring system spans 404,880 miles (651,591 kilometers). Consider that the average distance between the Earth and our Moon is about 239,000 miles (384,000 km), one can see how our system would fit nicely within Saturn’s rings.

This image is even more remarkable because of the other celestial objects that are also present. Our home planet lies to the lower right of Saturn, while Mars and Venus are above and to the left. There are also seven Saturnian moons visible in the picture. Follow this link for a larger annotated image that highlights these objects.

This isn’t the first time Earth has been photographed from Saturn or even further from home. Check out the blog post “The Pale Blue Dot” if you would like to read more.

One last spectacular image of Saturn, which can be seen below was taken on October 10, 2013. Here, Cassini is flying over the top of the planet and the amazing hexagonally shaped weather system is in full view. If you zoom in to the image you can see numerous smaller cyclonic storms and circular weather patterns near the pole. (Click on the picture for a larger image.)

Saturn from above. October 2013. Image Courtesy of NASA/JPL

These are only a few representations of this beautiful planet that can be found at NASA’s JPL website. For a more detailed discussion of how the latest image of Saturn was taken and processed, check out CICLOPS (Cassini Imaging Central Laboratory Operations)  “The Day the Earth Smiled”.

Two last comments:

The amazing success of the mission, and the wealth of knowledge that Cassini has brought to us about this planet makes me wish that NASA had the foresight to launch similar probes to Jupiter, Uranus and Neptune. Imagine the wonders we would have discovered!

Lastly, Carl Sagan tried to put our fragile existence into perspective when he lobbied NASA to take the first image of our planet from the distant reaches of our Solar System – the original “Pale Blue Dot” image in 1990. For me, it’s hard to look at our planet as a few pixels in the vast blackness of the cosmos and not be reminded of the stark reality that this is the only home mankind has had—and will have—for many, many generations to come. We can’t afford to waste it.

Till next time.

RC Davison

Star Trek Into Darkness – OMG!

Posted on by
2

A bit different post this time…More of a rant!  Sorry, it goes on forever!

Having grown up with the original Star Trek, I can only watch the newest assault on the Star Trek franchise from the perspective that it is an alternate universe from the original Star Trek Gene Roddenberry created. Taking such a point of view allows me to watch the new crew of the Enterprise take on the Universe without grimacing [much] at their antics, relative to the well established history and timeline of the original Star Trek.

I found that I could accept the cast and revised crew, and I tried really hard to like what I was seeing on the big screen, but what I was seeing made me feel that the movies were built around the action and special effects and not much more. In this day and age you need more than the visual shock and awe, you need a storyline behind the visuals that ties everything together in a way that doesn’t leave the viewer pondering if what they just saw makes any sense.

Case in point: The first Star Trek movie shows us a youthful Jim Kirk racing headlong toward a precipice in his step-father’s vintage Corvette Stingray. We watch as he jumps out of the car when it is about 40 feet from the edge. We all know that Kirk manages to slide to a stop, but we all also know that this is physically impossible and just ridiculous. So right at the beginning the director insults our intelligence by trying to get us to believe this is even plausible. Why not have Kirk jump out 300 feet before the edge? You still get the car going over, but you also get a scene that is at least plausible. Or better yet, have the officer on the air-cycle pull Kirk out of the car just as it goes over the edge. (I found it interesting that the beginning of the newest movie we find Kirk once again racing toward a precipice, but this time he goes over the edge. I’m still trying to figure out what that symbolizes.)

There’s another bug I have about Sci-Fi series and that’s jumping through time—and they all do it. I have always contended that when a science fiction show starts to use time travel to propagate the storyline, they’ve run out of ideas and are scrambling for something to continue the show. The television series Enterprise used this plot device in it’s pilot episode. It lasted only 4 years, with a mediocre following. The premise for the show was good, the cast could do the job, but the material that was produced for the show was dismal. The first new Star Trek movie used the time traveling ploy and, as far as I’m concerned, turned out a movie that was extremely disappointing.

Star Trek Into Darkness tries to remake the original Wrath of Khan movie, but with the alternate universe twist in full force. That could work if the story wasn’t full of holes and inconsistencies. It seems more and more that movies are built around the neat special effects that are thrown in here and there, regardless if they make any sense or not—let’s do it for the WOW-factor.

If you’re still with me, hang on a few more minutes and I’ll explain. Note: If you haven’t seen the movie yet, be forewarned that there are many spoilers to follow.

  1. Opening scene: Why is the Enterprise underwater?? Were they trying to sneak up on the natives of Nibiru? Did somebody forget that they have transporters on board? While it looks really spectacular coming out of the water, it makes absolutely no sense to do this other than the wow-factor. Plus it ignores the fact that a vessel that is designed to operate in the vacuum of space is not optimized for the pressures placed on it being hundreds of feet under water. A submarine would make a better spaceship than a spaceship would a submarine.
  2. Scotty doesn’t want to fly over the volcano to rescue Spock because it’s too hot? Lava is about 1200°C or 2200°F. The NASA space shuttles routinely handled temperatures of almost 2500°F. Spock was sitting on a block of basalt in the caldera in his spacesuit! I would think that the technology of the 23rd century would be able to handle those temperatures and more for their starships. And, don’t they have shields? Heat is just infrared electromagnetic radiation.
  3. Khan wipes out the Data Archive (Top Secret Section 31) with a ring that explodes when placed in water. Impressive! But, he proceeds to shoot up the conference room with an assault vehicle reminiscent of a Huey Cobra helicopter with a 50 caliber machine gun! Extremely inefficient since he didn’t manage to kill the guy he was after. Why not beam in a bomb? Use a phaser? Hell, with his capabilities he could have walked into the room and killed them all without breaking a sweat! (See number 12 below.)
  4. There is no security force at Star Fleet headquarters to take on this assault vehicle? (They better hope the Klingons don’t hear about that!)
  5. Khan then trans-warp beams to Kronos. (I won’t even get into the trans-warp beaming!) Why Kronos? Why didn’t he just beam to the new starship which was hanging out in orbit around Jupiter and take it over? (See number 12 below.)
  6. Admiral Marcus then gives Kirk a special new photon torpedo to take out Khan—72 of them! At this point we and Kirk don’t know that they are shielded with a body inside in cryogenic suspended animation (Khan’s friends). Hmmm, seems like the Admiral may have wanted to do serious bodily harm to these frozen people. Wouldn’t it be easier to just phaser Khan’s crewmates and be done with them? I’ve got to wonder why would anyone authorized the work to build a torpedo that had a cryogenic life-support system in it? And, of course to make sure you kill Khan you can’t shoot just one torpedo, you’re directed to shoot all 72 of them? That didn’t raise a flag in Kirk’s head?
  7. Scotty quits when the new torpedoes are brought on the ship because they’re shielded and he needs to know what’s inside. But wait, isn’t Scotty the chief engineer? Or did I miss something and his real job is the ship’s cargo master? Doesn’t the ship of this size have a weapons officer, or an armorer that would be looking after these weapons?
  8. Scotty resigns, so Kirk (Did Kirk even finish going through Star Fleet Academy?) assigns Chekov, the navigator, who’s been shadowing Mr. Scott, to head up engineering? (He gets to wear a “red shirt”! Oh no!) Didn’t Scotty have a subordinate that helped him in engineering who would be the next logical chief engineer as opposed to a navigator just out of Star Fleet?
  9. Uhura and Spock on an away-team? Okay, that’s fine…but wait! Really? You want two romantically engaged, personnel, who are obviously having a lover’s spat to attend an away-team on this critical mission? And, they then argue on the way down to the planet, pulling Kirk (the Captain) into their quarrel? Is this Star Trek or an episode of The Office? It’s a humorous moment, but if you think about it, it’s just all wrong! It’s like the writers/director can’t decide if they want this to be a comedy or an action movie.
  10. Shouldn’t Spock stay on the ship in command in case the Captain gets in trouble? (Really, the Captain should have his butt parked in the chair and the first officer should be leading the away-team.) Nope! You give command to your helmsmen! Go Sulu!
  11. Then they want to disassociate themselves from Star Fleet by wearing civilian clothes and flying a civilian ship…Ah, excuse me…what about that federation starship (Enterprise) that is floating derelict in Klingon space? I would think that might be a red flag to the Klingons that these people are probably not your average family out for a Sunday drive.
  12. Then of course the Klingons are so inept or Khan is so superior that he takes out the compliment of 3 Klingon Birds of Prey, plus destroys two of their ships. Gee, no one on any of the Klingon ships thought to just blast him to smithereens using their ship’s weapons?
  13. Back to the photon torpedoes: Of course, the chief medical officer on the ship is the logical choice to accompany the science/weapons officer in opening a mysterious photon torpedo to see what’s inside? I guess there is no one in sickbay that needs his attention…Oh, that’s right! They needed someone with the steadiest hands on the ship…How many surgeries will be done in the 23rd century with a handheld scalpel?
  14. Back to our solar system: Scotty just flies up to the top secret space base in orbit around Jupiter where they are building the newest star ship – USS Vengeance? Nobody is watching the radar screen? No identity challenges? No security? (I hope the Klingons don’t hear about this!)
  15. Okay, the Vengeance beats the tar out of the Enterprise, which manages to jump into warp, thanks to Chekov’s amazing engineering efforts. The Vengeance knocks the Enterprise out of warp and they end up 137,000 km from Earth (85,000 miles from Earth). Note that the Moon is 235,000 miles from Earth on average, so they are really close to the planet. Doesn’t Earth have any defense systems monitoring local space? Star Fleet headquarters is in San Francisco and they have no defensive systems that pick up these two ships and go and investigate? Where’s NORAD—or its 23rd century equivalent?? You’ve got the Enterprise still getting beat up by a ship that’s twice as big—that’s almost 2000 feet long! No one on Earth notices this? There are no radio transmissions from Enterprise? A call for help? Standard telemetry that tells Star Fleet—“Hi honey we’re home?” (I hope the Klingons don’t hear about this!)
  16. Well, lets talk about the Vengeance. (The impression is that Khan was involved in designing it. Pretty good for someone who technology background is 200 years old!) Why is it so huge if you don’t need a large crew to a man it? It was designed to be run by a minimal crew and built for combat, then it would make sense that it would be as small as possible—just crew, engines and weapons. It seems to be another case of applying the WOW-Factor!
  17. I just loved the flame-throwing thrusters (very retro!) on a starship that uses antimatter for warp drive and has anti-gravity devices on board. The gurneys in the hospital had no wheels, apparently using an anti-gravity system! I’m just glad that someone filled the fuel tanks for the Enterprise before they left space dock.
  18. And Scotty, bless his heart, has stowed away on the Vengeance and survives running the entire length of the empty engine room to open the hatch for Kirk and Khan. But, unfortunately, Scotty is caught in his attempt to help them. Luckily, though, the person who catches him had to be the most stupid security officer in Star Fleet!
  19. Excuse me! Detonating 72 photon torpedoes, inside the engine room of the Vengeance does not obliterate the starship? Of course not. You have to keep Khan alive…
  20. The Enterprise is in free-fall to Earth and there is no gravity on the ship because the power is out and gravity systems are failing. Then why isn’t everyone floating?
  21. The Kirk/Spock switch at the end from the original Wrath of Khan ending is almost comical, as is the resurrection of Kirk. If you didn’t watch the original Wrath of Khan then the demise of Kirk would have been a much more serious scene.
  22. The Federation, again defenseless does nothing as the Vengeance crashes into San Francisco…
  23. They can’t beam up Khan and Spock as they are fighting on the vehicle flying through the city, because they keep moving and they can’t get a lock on them. But, in the first movie Chekov beamed Kirk and Sulu up while they were in free fall to the planet Vulcan. And, they can beam someone down to the vehicle that’s moving?
  24. And lastly, (Finally!) there are no security people on the Enterprise to beam down and tell Spock not to kill Khan, as well as provide a little help, so they have to beam their communications officer down?
  25. Whoops! One more: Of course, let’s just refreeze Khan and his crew for a new movie somewhere down the road!

There’s more, but I’ve taken enough of your valuable time. I’m sure that everyone involved in the production of Star Trek Into Darkness worked hard to produce the final product and I commend them on their efforts. But, if you are going to spend $200 million to make a movie, how much more does it cost to get a script that gives the audience a cohesive, plausible storyline, with plausible characters, action and effects? Probably nothing. There are many excellent writers out there who have written intelligent stories, filled with action, intrigue and adventure that would be happy to provide the script for the next Star Trek movie.

Till next time,

RC Davison

Death in the Cosmos

Posted on by
Reply

 

Death, is it the end of existence?

A large star will end its life in a supernova. A spectacular explosion that allows the star to outshine the galaxy it resides in. This explosion will seed the cosmos with elements that were made within the star as it aged, along with elements (like gold and platinum) that were directly produced during the supernova.

Supernova in the galaxy NGC1365. Image courtesy of Martin Pugh (http://www.martinpughastrophotography.id.au/)

Our Sun will not explode; it does not have enough mass to generate a supernova. But, it will eventually become a red giant and engulf the Earth, as it begins to burn helium after exhausting the hydrogen at its core. As the star consumes its helium it will go through a series of oscillations, shrinking and expanding. This process will blow off layers of material from the star that will form a nebula, called a planetary nebula, which will mark the location of our star as it shrinks down to a small white dwarf star and slowly cools over the eons.

The Ring Nebula, a planetary nebula 2000 light-years away. Image courtesy of NASA.

In both cases, material from the star is returned to the cosmos that can become the seed material for a new star and planetary system. So, the death of a star is really the beginning of a new generation.

Humans, every plant, animal, rock and drop of water on this planet were all formed from the elements cast into the Universe by stars that have passed out of existence. When we pass from the world of the living and are interred on this Earth, we will return our borrowed elements to Mother Earth. And, when the Sun goes through its final stages of life and our planet is consumed by the bloated star, everything on it will be returned to the cosmos and become the raw materials for a new solar system and maybe someday, a new form of life. As Carl Sagan said, we are all star stuff.

But, what of that collection of electrical impulses makes each of us unique, that makes us human—the soul, if you will? What happens to that entity?

Those with religious beliefs will say that the soul moves on to heaven or hell or some other after-life, depending on one’s conduct on Earth. Scientists may try to measure the change in electromagnetic energy a person has after death. But, the former provides no proof that we transcend to a higher plane of existence, while the latter only quantifies the energy we possess and doesn’t reveal the unique life-force it contains. The bottom line is that we just don’t know. That spark which makes us – us, is surely contained within the bounds of the cosmos. But, what it is, how it works, where it comes from and where it goes is a mystery.

Just as the star lives on by casting its elements throughout the cosmos, so does a person live on through the people they encounter in day-to-day life, from family to friends to co-workers to strangers. We all can carry some part of the essence of that person into the future, and we will pass it on to our friends, family and acquaintances through the stories we tell and the actions we take.

This cosmos we live in is so vast, with so many unknowns. We have many questions to answer, and many more to ask.

This post is dedicated to the memory of my father, Edwin Allen Davison Sr. (June 30, 1925 – September 21, 2013). His spark has been returned to the cosmos. I will miss our discussions of the wonders of our Universe…

Hubble Extreme Deep Field. Image courtesy of NASA

Till next time,

RC Davison

 

Neutron Stars, General Relativity and Elephants

Posted on by
Reply

The discovery of an unusually massive neutron star with a white dwarf companion was revealed in a paper published by John Antoniadis, a PhD student at the Max Planck Institute for Radio Astronomy and others on the international team this past April. Using radio telescopes from observatories around the planet to identify and study the neutron star, and the European Southern Observatory’s (ESO) Very Large Telescope (VLT) with its FORS2 spectrograph located at the Cerro Paranal observatory in Chili, to study the white dwarf star, the astronomers have discovered the most massive neutron star found to date. Labeled as PSR J0348+0432, the neutron star weighs in at twice the mass of the Sun.

White dwarf star orbiting a pulsar, a neutron star beaming radio frequency energy, generating gravity waves as they revolve about a common center. Image courtesy of ESO

So what? One might ask.

Well, what’s remarkable is that this mass exits in a sphere only 12.4 miles (20 km) in diameter. This means that the density of the material inside this defunct star is on the order of 1 billion tons per cubic centimeter—the size of a sugar cube! The force of gravity on the surface of the star is 300 billion times stronger than what we experience here on Earth.

This super dense ball is rotating 25 times per second and has a white dwarf companion star with a mass 0.17 that of our Sun and a diameter of 56,000 miles (90,000 km) orbiting it every 2.5 hours. This neutron star is also a pulsar. It sends a highly directional beam of radio frequency energy out into the cosmos and provided the pulsating beacon that we detected to locate this unique stellar system.

This super massive star along with it’s companion provides a wonderful natural laboratory for Earth based astronomers to study Albert Einstein’s General Theory of Relativity, which describes how space is curved by mass and energy and we observe in part as gravity. Studying this high intensity gravitational system may help us better understand gravity waves, predicted by Einstein’s theory, and explore the realm where general relativity and quantum mechanics may meet.

The team of astronomers have already measured a reduction in the orbital period of 8 millionths of a second per year due to energy being radiated from the system by gravity waves, as predicted by general relativity. Although gravity waves have been inferred by this and other binary systems, they have yet to be detected by the Laser Interferometer Gravitational Wave Observatories—LIGO—facilities on Earth.

But, wait! A sugar cube size piece of neutron star stuff that weighs 1 billion tons? How do you wrap your head around that piece of information? How do you compare that to everything you touch in your day-to-day routine? Let’s see what a billion tons of stuff might look like.

A good, massive object that most people have a concept of might be the African bull elephant.

Weighing in at about six tons on average, ten feet high by twenty feet long and eight feet wide, we would need only 167 million bull elephants to equal one cubic centimeter of neutron star material. That’s a lot of elephants!

To get a better perspective on how large this number of elephants is, consider if you packed these pachyderms side by side, front to back, you would cover an area of 26.7 billion square feet. (Whoops! We’re back to billions again. Better to convert that to square miles/kilometers.) That’s 956.5 square miles (2477 sq km); equivalent to a square with sides 30.93 miles (49.8 km) long. You could comfortably park them all in the tiny country of Luxemburg, which has an area of 998 square miles (2586 sq km), with a little room to spare.

How about something bigger, even more iconic, like the Empire State Building (ESB). Standing 1,454 ft (443.2 m) high, it has an estimated weight of 365,000 tons. We would need only 2740 ESBs to offset a balance with 1 sugar cube-size piece of neutron star stuff on it. That’s at least a number we can begin to have an intuitive sense for.

So how much area would 2740 ESBs cover? With a foot print of 79,288 ft2 (7240 m2 ) or .003 square miles (.007 square km), our collection of buildings would cover 7.8 square miles (20.3 sq km) – about 1/3 of the island of Manhattan, which has an area of 22.96 square miles (59.5 sq km). It’s a bit hard to imagine a third of Manhattan covered in Empire State Buildings. But, we can reduce the number and get a better handle on a billion tons.

Let’s take our Empire State Building and make it completely out of gold, all 37 million cubic feet (1.04 million cubic meters) of it. With gold weighing 1204 pounds per cubic foot, the solid gold building would weigh 44.5 billion pounds or 22.3 million tons. Now all we would need is 45 of these precious metal buildings to reach 1 billion tons.

This gilded collection would cover about 23 city blocks or an area from where the ESB is now to Times Square, assuming two buildings per block. Try to imagine this the next time you fly to New York City: the core of downtown Manhattan populated with 45 gleaming, solid gold Empire State Buildings and all that is equivalent to 1 cubic centimeter—one sugar cube-size of neutron star stuff.

Hopefully this helped you get a little better feel for what a billion tons might be. It’s helpful to do these simple calculations and comparisons and try to put into perspective or get a better grasp on some of the enormous numbers that come out of the study of this amazing Universe we live in.

When considering the cosmos and all the numbers we produce to describe it, I cannot help but feel that all we hold dear on this tiny blue planet, floating through the vastness of space, is insignificant when compared to what we are immersed in. Yet, we are sentient beings, and curious about the Universe we live in and that makes us very significant, because for all we know now, we are the only creatures in this entire cosmos that are looking up and asking these big questions.

Till next time,

RC Davison

Link to the research paper: “A Massive Pulsar in a Compact Relativistic Orbit”, by John Antoniadis et al.

 

 

Asteroid 2012 DA14, Tunguska Impact, Meteor Crater, and the Russian Meteor of 2013

Posted on by
2

(Post updated 2/19/2013 with latest assessment on asteroid from ESA.)

Wow! Two wake up calls for the planet Earth in one day! Maybe it’s about time that the people of planet Earth realize that they are inside the pinball machine that makes up our Solar System. Sooner or later that ball is going to hit us head on. Today we were lucky – twice!

Russian Meteor, February 15, 2013

The spectacular meteor that streaked across Russia’s sky Friday morning has been estimated to be about 56 feet (17 meters) across, weighing in at more than 7000 metric tons and moving at speed around 40,000 mph (64, 373 km/h). It exploded about 9-12 miles (15-20 km) above the surface of the Earth with an equivalent of 500 kilotons of TNT—30 times the energy of the Hiroshima atomic bomb.  The consequent shockwave shattered windows and damage buildings in and around the Russian city, Chelyabinsk, resulting in over 1000 injuries.

This meteor was not related to the flyby later in the day of asteroid 2012 DA14. This asteroid skimmed by the Earth at a distance a little over 17,000 miles (27,400 km). Friday, February 15, 2013 could have turned out a lot different if either of these cosmic messengers had a slight change in course, which in the case of the Russian asteroid, could have detonated lower and over a more populated area or for 2012 DA14, a direct hit instead of a near miss.

We have two good examples of the consequences of an asteroid the size of 2012 DA14 (150 feet, 45 meters, ~130,000 metric tons) hitting the Earth in the Tunguska explosion of 1908 in Siberia (120 feet, 37 meters, ~100,000 metric tons) and the nickel-iron meteor (150 feet, 50 meters, ~270,000 metric tons) responsible for Meteor Crater in Arizona.

Map of Tunguska Impact (Sullivan 1979 and Kridec 1966.)

The Tunguska explosion occurred in the air above Siberia at a height of about 28,000 feet

(8500 meters) and generated the equivalent energy of about 1000 Hiroshima atomic bombs. The result was over 800 square miles of forest destroyed and a shock waves that

were recorded as far as western Europe and registered a magnitude 5 earthquake. As of today, no crater has been found to mark an impact of the remnants of the asteroid, leading some to think it might have been piece of a comet that entered Earth’s atmosphere that day, which is made mostly of ice.

Meteor Crater (AKA Barringer Crater) Arizona – Wikimedia Commons

Contrasting Tunguska is the nickel-iron meteor that did leave a crater in what is now Arizona. About 50,000 years ago this meteor entered the atmosphere at a speed of about 27,000 mph (43,000 km/hr) and fragmented to some degree due to the stresses associated with entry into the atmosphere, but the bulk of it hit the Earth creating a crater that is 4000 feet (1200 meters) in diameter and 570 feet (174 meters) deep. The explosive energy released from the impact has been estimated to be as high as 200 times that of the bomb dropped on Hiroshima.

Impact effects at Meteor Crater – Image courtesy of the Space Imagery Center and/or David A. Kring

We see two very different effects from two similarly sized asteroids.  But, it is the different composition that makes the difference.  The high density nickel-iron meteor survives the descent to the surface, while the less dense, ice-rich meteor fragments due to the high stresses experienced in its passage through thicker layers of the atmosphere. The temperatures experienced by these fragments can reach 45,000 °F (25,000 °C) causing the massive fireball and resulting shockwave and destruction.

We don’t, by any stretch of the imagination have knowledge of every asteroid in the Solar System that poses a potential threat to Earth.  The more we look the more we see, and with regard to near Earth asteroids (NEA), the sooner we find them the better.  It is possibly the only natural disaster we may be able to avert, given enough time.

Till next time,

RC Davison

References:

Russian asteroid impact ESA update and assessment

The Tunguska Impact – 100 Years Later

Damage by Impact — the Case at Meteor Crater, Arizona

Barringer Meteor Crater and Its Environmental Effects

 

Asteroid Flyby and Pricing Change on ORBITAL MANEUVERS

Posted on by
1

This coming Friday, February 15, 2013, we will have a flyby of asteroid 2012 DA14. This asteroid is about 45 meters (150 feet) in diameter and is most notable in that it will pass within the orbits of our geosynchronous satellites, which typically orbit about 22,000 miles (about 35,000 km). It will skim past the Earth at an altitude of about 17,000 miles (27,000 km), so there are no concerns about an impact, but it could (very unlikely!) take out a satellite on its way through our neighborhood.

Trajectory of 2012 DA14 (Image courtesy of NASA)

It is interesting, and a bit concerning to note that the object that exploded over Tunguska, Siberia in 1908 is estimated to be about 120 feet (36 m) in diameter! Here’s an excerpt from NASA’s site on the event:

“It is estimated the asteroid entered Earth’s atmosphere traveling at a speed of about 33,500 miles per hour. During its quick plunge, the 220-million-pound space rock heated the air surrounding it to 44,500 degrees Fahrenheit. At 7:17 a.m. (local Siberia time), at a height of about 28,000 feet, the combination of pressure and heat caused the asteroid to fragment and annihilate itself, producing a fireball and releasing energy equivalent to about 185 Hiroshima bombs.”  – NASA Science News

This leveled over 800 square miles (2072 sq km) of tundra! Imagine that destruction over a major metropolitan area today! Although small, relatively speaking, these objects are moving at very high velocities, which translates into very large amounts of energy that can be released when they explode or impact an object.

Fortunately for us, 2012 DA14’s orbit will cause it to just miss us, but it points out the potential for very catastrophic events to occur from objects that are relatively very small. It was by chance that we discovered it when we did, thanks to work by the Planetary Society.

Our surveillance of the asteroid threat has gotten better, but there is still need for improvement and more importantly, a plan of action to deal with an asteroid that will impact the Earth. This needs to be researched, tested and ready before we find that space rock with our name on it. There is work being done on this, but it is not at the level it should be.  We do not know when we might find a potentially lethal asteroid, and we don’t know how much time we will have to deal with it when it is discovered.  We need to be prepared.  The sooner the better!

Speaking of space rocks destined to impact Earth. The book, ORBITAL MANEUVERS discusses some of the consequences of a very large asteroid impacting the Earth and a stranded space shuttle crew’s attempt to survive the aftermath while in orbit. Part of the reason to write the book was to draw attention to this very real threat. To give more people the chance to read the book and get a sense of what is in store for us should a large impact occur, I’ve reduced the price on the book to $8.95 for the paper back, and $.99 for the electronic versions for Kindle and all other digital formats at Smashwords. It is also available on Apple’s ibooks.  Enjoy!

Keep looking up. You never know what you’re going to see!

Till next time,

RC Davison

Planet Found in the Alpha Centauri System – Could Pandora Be Discovered Soon?

Posted on by
Reply

Artist's illustration of the Alpha Centauri System. Credit: ESO/L. Calçada/Nick Risinger (skysurvey.org)

Reminiscent of the movie AVATAR, a planet has been discovered in the nearest star system to our Sun, Alpha Centauri. This is a trinary system consisting of three stars: Alpha Centauri A, B, and C. Alpha Centauri A is the same type of star as our Sun but slightly larger while its companion, Alpha Centauri B is slightly smaller and cooler. Alpha Centauri C is a red dwarf star also known as Proxima Centauri and is the closest star to our solar system at a distance of 4.22 lightyears. Alpha Centauri A and B orbit each other at a distance of about 23 AU (Astronomical Unit: 93 million miles/150 million kilometers) or about the distance between the Sun and Uranus.

This newly discovered planet is no Polyphemus, the gas giant in the movie that the moon Pandora orbited. The planetary system was in orbit around the star Alpha Centauri A. This planet (designated Alpha Centauri B b) is in orbit about Alpha Centauri B and has an orbital period or year of 3.236 days. It’s mass (minimum mass) is 1.13 times that of Earth and it orbits its star at a distance of about six million kilometers, 3.6 million miles.

The simple facts about this planet belies the huge effort that was put forth to push the envelope of the technology and analysis techniques to find the planet.  This information was gleaned out of data collected from over of four years of observations using the HARPS spectrograph at the ESO LaSilla Observatory (See Finding Exoplanets – Part 2: It’s All About the Mass for more information on the HARPS instrument.) The team of astronomers, lead by Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper were able to improve on the sensitivity of the HARPS instrument by taking into account:

  • The radial motion of the Alpha Centauri star system relative to Earth
  • The stellar oscillation modes for Alpha Centauri B, akin to seismic vibrations
  • The granulation of the star’s surface (the convective zones of rising hot plasma and sinking cooler plasma on the surface, which contribute noise to the measured radial-velocity of the star)

    Image of the granulation of the Sun's surface. Image courtesy of ESA

  • The rotational contribution of the star (as the star rotates, the side moving toward us will be blue shifted while the side rotating away from us will be red shifted)
  • Spots on the surface that are brighter or darker than the mean
  • Magnetic cycle activity
  • Light from Alpha Centauri A contaminating the spectrum of the B star
  • Instrument noise.

After extensive data reduction and analysis, the team determined that the star was wobbling at a velocity of 51 cm/sec (20 inches/sec) due to the planet’s motion. This is about 1.8 km/hr or 1.1 mile per hour!

Although the planet discovered is too close to its parent star to be habitable, at least with life as we know it, the analysis techniques developed to pull the presence of the planet out of the noise can be used to identify planets with a minimum mass of 4 times Earth’s mass in the habitable zone of a star. This opens up a new category of planets that can be searched for.  Note that this is the first planet found in the Alpha Centauri, it may not be the last. It may only be a matter of time before a planet (or moon) like Pandora from AVATAR is found in a star system in the Milky Way.

Till next time,

RC Davison

References:
Planet Found in Nearest Star System to Earth: http://www.eso.org/public/news/eso1241/
Paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1241/eso1241a.pdf

Lithium, Stars and Planets

Posted on by
Reply

On Earth, the element lithium has certain medicinal properties when applied to conditions like depression and bipolar disorder, and it is extensively used in the battery technology powering most of our portable electronics. In stars, the amount of lithium present is an indicator of the age of a star.

The older the star is, the lower the concentration of lithium measured in the photosphere – the part of the star that we can see. Typically as a star ages, lithium is moved through convective motion deeper into the star where the temperatures are higher and the element is consumed. When astronomers find a star that shows a higher than normal lithium content for its age, eyebrows get raised and heads get scratched.

After the big bang, the Universe (by mass) was about 75% hydrogen, 25% helium and extremely small trace amounts of lithium, all the other elements we have today have been synthesized in stars as they move through their normal life cycle.  Elements heavier than iron are produced when the more massive stars explode as supernova.  The first stars that formed after the big bang (called Population III stars) reflected the amounts of hydrogen, helium and lithium originally present.  Second generation stars (Population II) contained higher levels of the elements heavier than lithium thanks to the first generation enriching the cosmos, but these are considered “metal poor” when compared to Population I stars, like our Sun.  (Astronomers consider any elements heavier than helium to be metals.)

The planets that form around a star contain the primordial elements of the big bang, along with whatever new elements have been seeded in the protoplanetary dust cloud from novae and supernovae. Lithium is preserved in the relatively cold planets as they condense and solidify. If a planet containing lithium is pulled into its parent star, it will disintegrate, spreading its contents though out the star’s atmosphere. This mechanism can explain how a star can have a higher than normal lithium content for its age.  But, this process is transitory.  Eventually, the lithium will be processed by the star.

There have been two recent observations of stars that show higher than normal amounts of lithium:

One is associated with a red giant star (BD+48 740) that is suspected to have at least one planet orbiting it in a highly eccentric orbit. Dr. Alex Wolszczan, professor of Astronomy and Astrophysics at Penn State University, has led the team which discovered this youthful red giant. Evidence indicates that the star has a massive planet in a very elliptical orbit, which is unusual but can be attributed to gravitational interactions between planets in the solar system. This interaction may have contributed to another planet moving too close to the parent star and being engulfed as the red giant swells with age, giving rise to the higher than normal lithium content.

Red Giant engulfs one of its planets. (Image courtesy of NASA)

The other observation is of a star (#37934) in the globular cluster NGC 6121, also known as Messier 4 or M4.  The ESO (European Southern Observatory) has released an image of M4 and discusses the surprising discovery.

Globular cluster M4, NGC 6121 (Image courtesy of the European Southern Observatory)

This star peculiar in that it is exhibiting a much higher than normal level of lithium for the ancient stars (Population II) that typically make up globular clusters. In the paper presented on this observation the authors present two scenarios that may explain this star’s unusual concentration of lithium.  The first is that the star formed with a higher than normal amount of the element  – i.e. it was polluted by its environment.  The other thought is that the star, for some unknown reason, hasn’t processed the lithium like the rest of the stars in the cluster.  Both ideas are up for debate as there isn’t enough evidence to prove either one correct.

But, could this star have sacrificed one of its planets for a brief period of youthful lithium enrichment like BD+48 740? (This assumes that it has or had planets orbiting it.)

Star in M4 exhibiting higher than normal lithium levels. (Image courtesy of the European Southern Observatory)

Perhaps the discovery by Dr. Wolszczan and his team shows a stellar process that is more common than thought.  If one considers the high number of planets being discovered by Kepler, which is leading astronomers to predict even greater number of stars with orbiting planets, this idea may be even more plausible.

Another case of the cosmos leading us down a rabbit hole just like Alice in Wonderland – the more we look, the more we see and the more questions we raise.  The Universe just gets curiouser and curiouser!

Link to published papers:

BD+48 740 – Li overabundant giant star with a planet. A case of recent engulfment?

Lithium and sodium in the globular cluster M4. Detection of a Li-rich dwarf star: preservation or pollution?

Till next time,

RC Davison

Galaxies in Collision

Posted on by
Reply

In the vastness of the cosmos it seems amazing that objects run into each other, but they do. The pervasiveness of gravity has dominated and shaped the Universe as we see it today, from simple planets and solar systems to vast galactic clusters containing thousands of galaxies bound together. Galaxies collide, and galactic collisions create some of the most beautiful structures we’ve seen in our search of the cosmos.

Here we have The Mice:

Two galaxies colliding, known as The Mice - NGC 4676. Image Courtesy of NASA/Hubble Space Telescope

The Exclamation Point:

Arp 302 - Two galaxies about to collide - Image courtesy X-ray NASA/CXC/IfA/D.Sanders et al; Optical NASA/STScI/NRAO/A.Evans et al

Sometimes what appears to be a collision about to happen is really a case of one’s perspective, as can be seen in this image from the Hubble Space Telescope of NGC 3314.

Colliding galaxies? Not really. Image courtesy of NASA/Hubble Space Telescope

The galaxy that we see almost face-on – NGC 3314a is in the foreground and is tens of millions of light years from the background galaxy NGC 3314b. These two galaxies will not become another statistic in the annals of galactic collisions. But, the same can not be said for our own Milky Way galaxy and the Andromeda galaxy (M31).

In the next four million years or so, these two galaxies will begin to become one through a graceful pas de deux that will take millions of years and result in what theory predicts will be a large elliptical galaxy. This information, along with some amazing simulations and illustrations can be found at the Hubble Space Telescope’s site.

Here’s a graphic illustrating the collision showing the paths of the two galaxies along with another galaxy in our Local Group, Triangulum (M33):

Illustration of the Milky Way and Andromeda galaxies ultimate demise. - Image courtesy of NASA/Hubble Space Telescope

In this artist’s conception, the collision is seen from the perspective of an observer on Earth.

Illustration of the Andromeda galaxy's approach - Image courtesy of NASA/Hubble Space Telescope

The last few frames shows how Andromeda dominates the night sky and effectively blocks our view of that portion of the Universe. Future astronomers will not be able to appreciate the night sky as we are able to today.  But, who knows if humans will still be observing the Universe by the time this event takes place.

Looking at these images I can’t help but wonder about the alien astronomers living in the Triangulum galaxy. What a spectacular view they have of this doomed pair of galaxies. I wonder if they have mapped out the motions of these island universes (as they were once known) and understand that they will eventually collide. And, even more mind-boggling: Are they looking at us and wondering if someone is looking back?

Till next time,

RC Davison

 

Andromeda – Beyond the Blue

Posted on by
Reply

Hopefully we are all aware of the fact that ultraviolet rays from the Sun are bad for our skin.  The reason they are hazardous is because of the high energy that that they possess, which allows them to penetrate our skin and damage the cells internally. UV is a small part of our Sun’s emissions but UV radiation is a major component of the energy emitted by very hot, massive stars, as can be seen in the image below from NASA’s Galex (Galaxy Evolution Explorer) satellite.

Andromeda Galaxy in UV - Image courtesy of NASA

These stars that line the arms of the Andromeda galaxy are the result of dust and gas that form the structure of the arms and consequently, the birthing place of new stars.  Blue giants have very high surface temperatures ranging from 10,000 to more than 40,000 degrees Kelvin.  The more massive the star, the hotter it is and the more it will radiate in the ultraviolet.  But, running hot and massive comes with a cost.  These blue giants will burn out in supernovae in a few tens of million of years. (A very short time – astronomically speaking!)  Compare this with our Sun, which has a surface temperature of about 6000 degrees Kelvin and will be around for at least 10 billion years.

Below you can see Andromeda in a Hubble image in the optical spectrum fading to the ultraviolet image from Galex.  It’s easy to see that these high-powered stars reside in the dusty arms of the galaxy.  In a few million years the Milky Way Galaxy will have a ring-side seat to view these blue giants as they spectacularly end their lives!

Andromeda from Hubble in visual and UV from Galex

For more on the Andromeda galaxy take a look at an earlier post to see Andromeda in a different light: The Many Faces of Andromeda.

Till next time,

RC Davison