[/caption]The Russian supply ship for the International Space Station successfully launched from Baikonur Cosmodrome in Kazakhstan at 2:37 pm EDT (10:37 pm Moscow time) on Thursday to carry 2.5 tonnes of supplies to the orbiting crew. Progress 33 will take over from Progress 32 that was filled with rubbish and unwanted instrumentation and de-orbited on May 6th, sent on its way to burn up over the Pacific Ocean on May 18th.
It seems the spaceship exchange went according to plan. Progress 33 launched, Progress 32 de-orbited and the space station is stocked until the next delivery.
However, a small village in South Siberia didn’t have such a harmonious evening; a chunk of the Progress rocket booster fell onto a house.
This time, local residents reported hearing two sharp cracks and then a crash when something fell on the roof of a two-storey apartment block. Immediately the emergency services were called and fire fighters found a 1×4 foot piece of metal. It has been confirmed that this piece of debris originated from the Progress rocket launched earlier that night.
Fortunately there were no injuries and no significant property damage.
Regardless, the Russian space agency appears to be concerned that somebody is out to get compensation. “There is only one fragment and the house is not within the calculated area of possible debris fallout,” said a space agency spokesman. “In any case, there are no casualties or material damage, according to our information.”
The agency added that locals may have found the rocket debris elsewhere, transported it to Baranovka, put it on the roof and then claimed it fell from the sky.
To be honest, so long as there are no faked concussions or claims of “pain and suffering”, I suspect the residents won’t be suing for damages. (As there doesn’t appear to be any damage.)
I hope they get to keep the rogue bit of rocket though. That would make a great trophy in the village bar!
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Our own Milky Way is an example of a grand spiral; a vast collection of 200 to 400 billion stars. Much smaller galaxies than our own are known as dwarf galaxies. They only contain a few billion stars, and have a fraction of the mass of the Milky Way.
A good example of a dwarf galaxy is the Large Magellanic Cloud, located about 160,000 light-years from Earth. It contains about 1/10th the mass of the Milky Way, and has about 10% of its stars. Two other dwarf galaxies are even closer to the Milky Way, and have been captured by our galaxy’s gravity. Other dwarf galaxies are just remnants that have been torn apart by the Milky Way’s gravity, and are currently being incorporated into the structure of our galaxy.
Some astronomers think that the largest globular cluster in the Milky Way, Omega Centauri, might have once been a dwarf galaxy that had its outer stars stripped away.
Just like their larger cousins, dwarf galaxies can be classified into three varieties: dwarf elliptical galaxies, dwarf irregular galaxies, and dwarf spiral galaxies.
The smallest dwarf galaxies in the Universe are known as ultra compact dwarf galaxies. These are a recently discovered class of galaxies not much more massive than a globular star cluster. They can be as small as 200 light-years across and contain about a hundred million stars. It’s thought that ultra compact dwarf galaxies are just the cores of dwarf elliptical galaxies that were stripped of gas and outlying stars.
Our Local Group of galaxies contains just three large spiral galaxies: Andromeda, the Milky Way, and the Triangulum Galaxy. All of the others are dwarf galaxies of varying sizes.
There’s a list out there somewhere of the most extreme things in the Universe. Blazars must certainly be on that list. Astronomers used to think that blazars were variable stars, but strangely, they didn’t change in brightness in any predictable way. But then in the 1970s astronomers realized that these objects were actually millions of light-years away. They were outside our galaxy, and yet they were so bright they outshone all the rest of the stars in their galaxy.
So what is a blazar? Simply put, it’s the core of an active galaxy, where the galaxy is oriented face on, so a relativistic jet blasting out of the galaxy is oriented directly towards the Earth.
All large galaxies seem to contain supermassive black holes. There are times when these black holes are actively feeding on infalling material. In fact, so much material tries to get into the black hole that it backs up into an accretion disk around the center of the galaxy. The gravitational pressure is so extreme that the material heats up to millions of degrees and becomes like a star, emitting a tremendous amount of radiation. The rapidly spinning black hole generates a powerful magnetic field that whips up the material into jets that blast above and below the black hole. Material caught in these jets is accelerated nearly to the speed of light and fired out for hundreds of thousands of light-years.
When we see a blazar, we’re looking at an actively feeding galaxy face on. Furthermore, one of the relativistic jets is oriented so that it’s pointed directly towards us, and we can see the radiation emitted by both the black hole and the jet.
Even though these blazars can be as far as 9 billion light-years away, they’re still detectable by Earth-based instruments. Now that’s bright.
Everything in the Universe seems to be part of something bigger. Our Earth is part of the Solar System, the Solar System is part of the Milky Way, and even our Milky Way is part of the Local Group. The Local Group is part of the Virgo Cluster. But there is an end to this, the largest structures in the Universe are the superclusters, measuring hundreds of millions of light-years across and containing millions of galaxies.
Our own Milky Way is part of the Virgo Supercluster. This giant formation fills a volume of space 110 million light-years across and contains at least 100 galaxy groups and clusters. And you might be amazed to know that the Virgo Supercluster is just one of millions of superclusters in the observable Universe.
A typical supercluster contains 1015 times the mass of the Sun; that’s a quadrillion solar masses. It contains all the galaxy groups and galaxy clusters that seem to be associated with one another through mutual gravitational attraction. Astronomers have estimated that there are 130 superclusters located within 1.3 billion light-years of the Milky Way. Some example superclusters include Hydra-Centaurus, Perseus, and Cetus. Superclusters are typically named after the constellation they’re found in.
Superclusters show that our Universe is not evenly distributed. Instead, the large scale structure of the Universe is these giant superclusters connected together in long filaments. Seen from far enough away, the Universe would look foamy in texture, with superclusters strung out in filaments surrounding vast voids.
Astronomers in the southern hemisphere are lucky enough to have a clear view of the Large and Small Magellanic Clouds. Those of us in the northern hemisphere are totally out of luck. The Large Magellanic Cloud is a dwarf galaxy located about 160,000 light years away. In fact, it’s the third closest galaxy after the Sagittarius Dwarf and the Canis Major Dwarf Galaxies.
The Large Magellanic Cloud is only about 1/10th the mass of the Milky Way, containing a mere 10 billion stars worth of mass. This makes it the 4th most massive galaxy in our Local Group of galaxies, after Andromeda, the Milky Way and the Triangulum Galaxies.
It’s considered an irregular galaxy, without the grand spiral shape that we see with other galaxies, but it does have a prominent central bar. It’s possible that the Large Magellanic Cloud was once a spiral galaxy like the Milky Way, but a near pass with our galaxy or another distorted its shape, wiping away the spiral formation.
You can see the Large Magellanic Cloud with the unaided eye; no telescope is necessary. It’s visible as a faint cloud in the night sky, right on the border between the constellations of Dorado and Mensa. With a good pair of binoculars, you can see it much better; and it’s even bigger and brighter in a small telescope.
The Large Magellanic Cloud has large pockets of gas and dust, and it’s undergoing furious star formation. In fact, some of the largest, most active star forming regions ever observed are in the LMC. Astronomers have found 60 globular clusters, 400 planetary nebulae, and 700 open clusters, with hundreds of thousands of giant and supergiant stars.
In 1987, a supernova detonated in the Large Magellanic Cloud – the brightest supernova seen in 300 years. For a brief time, the supernova was visible with the unaided eye. The supernova remnant is still being studied as it continues to evolve and expand.
The Large Magellanic Cloud is named after the explorer Ferdinand Magellan, who completed the first circumnavigation of the Earth between 1519-22, and saw the clouds as part of his travels.
Small Magellanic Cloud. Image credit: NASA/ESA/HST
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If you live near the equator or in the Earth’s southern hemisphere and you watch the skies at night, you’re familiar with the Large and Small Magellanic Clouds. These are smaller galaxies nearby the Milky Way, and so they’re close enough and bright enough to see with the unaided eye. Let’s take a look at the Small Magellanic Cloud.
The Small Magellanic Cloud is a dwarf galaxy located about 200,000 light years from the Milky Way, making it one of our closest neighbors. At a magnitude of 2.7, it’s easily visible with the unaided eye from a dark location. Since it’s a galaxy, the Small Magellanic Cloud looks a bit like a detached piece of the Milky Way, over in the constellation of Tucana. Astronomers think that the SMC was once a barred spiral galaxy that was disrupted by the gravity of the Milky Way. It no longer has the familiar spiral arms, but it does still seem to have a central bar structure.
The Magellanic Clouds have been seen by people in the southern hemisphere for thousands of years, but they were made famous by the voyage of Ferdinand Magellan between 1519-22. The clouds were later observed by William Herschel with a 6.1 meter telescope at the Cape of Good Hope. This was a powerful enough telescope to reveal clusters and nebula inside the galaxy.
Astronomers once thought that the Small Magellanic Cloud was a satellite galaxy around the Milky Way, trapped in orbit by our gravity. More recent velocity calculations have thrown that theory on its head though. The Small Magellanic Cloud is moving fast enough that it can’t be captured by our gravity, and must be just passing us by.
Messier objects are celestial bodies that were observed by Charles Messier throughout his career. During his lifetime, any person who found a new comet became well known amongst their peers, but, also became a celebrity. Messier lived in what could be considered precarious times for professional astronomers. There were few jobs, so if you did make new discoveries you did not have a job.
Each Messier object is a body that first appeared to be a comet, but is not. Messier compiled a list of these objects in several additions; eventually ending with a total of 103 objects during his lifetime. His work was limited by the fact that he lived in the Northern Hemisphere, so could only observe objects that appeared in the night sky above 35.7° latitude.
It can be difficult to observe the entire Messier list. In addition to the 103 Messier compiled, his assistant and other researchers followed up on his side notes and astronomers now believe his list should contain a total of 110 objects. These objects are an interesting challenge for amateur astronomers to find, so there are several astronomical associations that offer rewards to anyone who observes them. A simple web search will garner you the information you need to participate.
Below is a set of links to an introduction to Messier objects as well as a link to an article about each of the individual Messier objects. Enjoy your research, then enjoy your observations.
The name “dark energy” is just a placeholder for the force — whatever it is — that is causing the Universe to expand. But astronomers are perhaps getting closer to understanding this force. New observations of several Cepheid variable stars by the Hubble Space Telescope has refined the measurement of the Universe’s present expansion rate to a precision where the error is smaller than five percent. The new value for the expansion rate, known as the Hubble constant, or H0 (after Edwin Hubble who first measured the expansion of the universe nearly a century ago), is 74.2 kilometers per second per megaparsec (error margin of ± 3.6). The results agree closely with an earlier measurement gleaned from Hubble of 72 ± 8 km/sec/megaparsec, but are now more than twice as precise.
The Hubble measurement, conducted by the SHOES (Supernova H0 for the Equation of State) Team and led by Adam Riess, of the Space Telescope Science Institute and the Johns Hopkins University, uses a number of refinements to streamline and strengthen the construction of a cosmic “distance ladder,” a billion light-years in length, that astronomers use to determine the universe’s expansion rate.
Hubble observations of the pulsating Cepheid variables in a nearby cosmic mile marker, the galaxy NGC 4258, and in the host galaxies of recent supernovae, directly link these distance indicators. The use of Hubble to bridge these rungs in the ladder eliminated the systematic errors that are almost unavoidably introduced by comparing measurements from different telescopes. Steps to the Hubble Constant. Credit: NASA, ESA, and A. Feild (STScI)
Riess explains the new technique: “It’s like measuring a building with a long tape measure instead of moving a yard stick end over end. You avoid compounding the little errors you make every time you move the yardstick. The higher the building, the greater the error.”
Lucas Macri, professor of physics and astronomy at Texas A&M, and a significant contributor to the results, said, “Cepheids are the backbone of the distance ladder because their pulsation periods, which are easily observed, correlate directly with their luminosities. Another refinement of our ladder is the fact that we have observed the Cepheids in the near-infrared parts of the electromagnetic spectrum where these variable stars are better distance indicators than at optical wavelengths.”
This new, more precise value of the Hubble constant was used to test and constrain the properties of dark energy, the form of energy that produces a repulsive force in space, which is causing the expansion rate of the universe to accelerate.
By bracketing the expansion history of the universe between today and when the universe was only approximately 380,000 years old, the astronomers were able to place limits on the nature of the dark energy that is causing the expansion to speed up. (The measurement for the far, early universe is derived from fluctuations in the cosmic microwave background, as resolved by NASA’s Wilkinson Microwave Anisotropy Probe, WMAP, in 2003.)
Their result is consistent with the simplest interpretation of dark energy: that it is mathematically equivalent to Albert Einstein’s hypothesized cosmological constant, introduced a century ago to push on the fabric of space and prevent the universe from collapsing under the pull of gravity. (Einstein, however, removed the constant once the expansion of the universe was discovered by Edwin Hubble.) Detail from NGC 3021. Credit: NASA, ESA, and A. Riess (STScI/JHU)
“If you put in a box all the ways that dark energy might differ from the cosmological constant, that box would now be three times smaller,” says Riess. “That’s progress, but we still have a long way to go to pin down the nature of dark energy.”
Though the cosmological constant was conceived of long ago, observational evidence for dark energy didn’t come along until 11 years ago, when two studies, one led by Riess and Brian Schmidt of Mount Stromlo Observatory, and the other by Saul Perlmutter of Lawrence Berkeley National Laboratory, discovered dark energy independently, in part with Hubble observations. Since then astronomers have been pursuing observations to better characterize dark energy.
Riess’s approach to narrowing alternative explanations for dark energy—whether it is a static cosmological constant or a dynamical field (like the repulsive force that drove inflation after the big bang)—is to further refine measurements of the universe’s expansion history.
Before Hubble was launched in 1990, the estimates of the Hubble constant varied by a factor of two. In the late 1990s the Hubble Space Telescope Key Project on the Extragalactic Distance Scale refined the value of the Hubble constant to an error of only about ten percent. This was accomplished by observing Cepheid variables at optical wavelengths out to greater distances than obtained previously and comparing those to similar measurements from ground-based telescopes.
The SHOES team used Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Advanced Camera for Surveys (ACS) to observe 240 Cepheid variable stars across seven galaxies. One of these galaxies was NGC 4258, whose distance was very accurately determined through observations with radio telescopes. The other six galaxies recently hosted Type Ia supernovae that are reliable distance indicators for even farther measurements in the universe. Type Ia supernovae all explode with nearly the same amount of energy and therefore have almost the same intrinsic brightness.
By observing Cepheids with very similar properties at near-infrared wavelengths in all seven galaxies, and using the same telescope and instrument, the team was able to more precisely calibrate the luminosity of supernovae. With Hubble’s powerful capabilities, the team was able to sidestep some of the shakiest rungs along the previous distance ladder involving uncertainties in the behavior of Cepheids.
Riess would eventually like to see the Hubble constant refined to a value with an error of no more than one percent, to put even tighter constraints on solutions to dark energy.
Ancient defrosting volcano on Mars, Credit: NASA/JPL/University of Arizona
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Malea Patera isn’t the name of one of the One Hundred and One Dalmatians, but it is the designation of an ancient volcano on Mars located on the outskirts of the Hellas impact basin. This isn’t your typical Martian landscape — just where are the red rocks and soil? — but is reminiscent of the markings on a Dalmatian dog. So what is going on here? This image was taken in early spring for this location in the southern hemisphere and the ground is covered with bright frost except for some dark splotches found in discrete patches. This is where the sunlight has penetrated the frost and initiated defrosting around discrete spots. The HiRISE scientists say that clearly, something is different about the patches, with the defrosting taking place, while the other areas remain frosty. One possibility is that these are (frost covered) dark sand dunes that heat up more easily than the surrounding terrain. However, to find out for sure, HiRISE will need to take a new image in the summer time to really know what is happening here. See below for a full view of this region, plus a few more of a mega-huge batch of images that were released today from the HiRISE camera on the Mars Reconnaissance Orbiter.
Full view of Malea Patera. Credit: NASA/JPL/U of AZ
Starburst Spider. Credit: NASA/JPL/University of Arizona
We move from dogs to spiders, but this, too is an unusual Mars image. Mars’ seasonal cap of carbon dioxide ice (dry ice) has eroded to create many beautiful terrains as it sublimates every spring. In this region we see troughs that form a starburst pattern.
In other areas these radial troughs have been referred to as “spiders,” simply because of their shape. In this region the pattern looks more dendritic as channels branch out numerous times as they get further from the center. The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below. The dust falls to the surface of the ice in fan-shaped deposits. Opportunity Imaged by HiRISE (ESP_011765_1780) Credit: NASA/JPL/University of Arizona
HiRISE spied the Opportunity rover heading through the dunes of Meridiani Planum. This image is about 400 meters across and was taken on January 29, 2009, Opportunity’s 1783rd sol (Mars day) on the Red Planet. Opportunity had driven 130 meters on the previous sol; wheel tracks are visible crossing dark ripples to the upper right of the rover. The ripples, which trend mostly north-south in this area, can be easily crossed by the rover unless they are very large (such as those right of center).
Using the HiRISE images allows the MER scientists to plan out Oppy’s route in great detail, avoiding potential hazards and targeting features of interest (such as the small craters below and left of center). HiRISE images are routinely used by the Opportunity operations team for these purposes, and to plan the route to distant Endeavour Crater, the long-term goal of Opportunity’s mission, about 17 km to the southeast.
Opportunity has been exploring Mars for over 5 (Earth) years; it will probably take another two years to reach Endeavour.
Check out over 600 observations that were just released by the HiIRISE team — 2 terabytes worth of data! And all are Martian eye candy (or is that “Hi” candy?) Hats off to HiRISE and her team!
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As you probably know, galaxies like our Milky Way are made up of billions of stars. But how did we get from the first particles of hydrogen and helium left over from the Big Bang to the beautiful spiral galaxy structures we see today? What was the process of galaxy formation?
Shortly after the Big Bang, the Universe was entirely hydrogen and helium with a few other trace elements like lithium. Thanks to tiny fluctuations in density of this material, it started to clump together into vast clouds of gas with increasing density. Astronomers think that the process of galaxy formation was really led by dark matter, which outnumbers regular matter. This invisible material was also clumped together, and it attracted regular mass with its gravity, channeling material together into larger and larger collections. And so, the first proto-galaxies were formed.
Within these proto-galaxies, clumps of material gathered together, and eventually created star forming regions, and within these regions the first stars began to form. These stars lived short violent lives, and seeded the next generations of stars with the material created in their powerful supernovae. These first proto-galaxies were gravitationally attracted to one other, and merged together into larger and larger structures, eventually becoming the large spiral galaxies we know today.
But the process of galaxy formation is still going on today. Our Milky Way is expected to collide with the Andromeda Galaxy in the next few billion years, and created an even larger elliptical galaxy. We can see examples of these largest galaxies elsewhere in the Universe.
