Starship Asterisk*

harry wrote:G'day

Jupiter another impact

http://www.spaceflightnow.com/news/n0907/20jupiter/

http://www.spaceflightnow.com/news/n0907/20jupiter/ wrote:
"It could be the impact of a comet, but we don't know for sure yet," said Orton.
"It's been a whirlwind of a day, and this on the anniversary of the Shoemaker-Levy 9 and Apollo anniversaries is amazing."

• _________ 2001
  
  Dr. Floyd: [prerecorded message speaking through TV on board Discovery while Bowman looks on] Good day, gentlemen. This is a prerecorded briefing made prior to your departure and which for security reasons of the highest importance has been known on board during the mission only by your H-A-L 9000 computer. Now that you are in Jupiter's space and the entire crew is revived it can be told to you. Eighteen months ago the first evidence of intelligent life off the Earth was discovered. It was buried 40 feet below the lunar surface near the crater Tycho. Except for a single very powerful radio emission aimed at Jupiter the four-million year old black monolith has remained completely inert. Its origin and purpose are still a total mystery.

harry wrote:A man with a small telsecope observed what people with BIG telescopes could not see.

Star*Hopper wrote:I admire APOD greatly, and count on them not only for presenting their 'routine' coverage, but also to cover breaking news. I've been somewhat disappointed that it's now been several days & APOD has not yet featured this fantastic news event. Thinking "Surely, today!" I started my morning rounds as is my normal habit, by opening up on APOD - only to find the featured object was the Lagoon nebula; & lovely tho it (today's image) is, it's been covered literally dozens of times before! And surely, nothing that couldn't bear waiting a day or two more to be presented later!

Chris Peterson wrote:

harry wrote:A man with a small telsecope observed what people with BIG telescopes could not see.

Of course big telescopes could see it. But there are a lot more small telescopes being used by amateurs than there are big telescopes being used by professionals, and amateurs are much more likely to be focused on a planet than are pros. Many new discoveries are made by amateurs for just these kind of reasons.

A lot of that may change in the next few years as large survey telescopes begin coming on line.

http://en.wikipedia.org/wiki/Pan-STARRS wrote:
<<Pan-STARRS (an acronym for Panoramic Survey Telescope And Rapid Response System) is a planned astronomical survey that will conduct astrometry and photometry of much of the entire sky on a continuous basis. By detecting any differences from previous observations of the same areas of the sky, it is expected to discover a very large number of new asteroids, comets, variable stars and other celestial objects. Its primary mission is to detect near-Earth objects that threaten to cause impact events. It is expected to create a database of all objects visible from Hawaii (three-quarters of the entire sky) down to apparent magnitude 24.

Pan-STARRS' first telescope, called PS1, is located at the summit of Haleakala in Maui Island, and went online on December 6, 2008, under the administration of the University of Hawaii. The other three telescopes completing the array will be completed by 2012 at a total cost of USD 100 million for the entire array.

Pan-STARRS will use four 1.8 m telescopes that will be located either at Mauna Kea or Haleakala in Hawaii. All four telescopes in the final 'PS4' system will point in the same direction: data will be compared to remove CCD artifacts due to chip defects and bad pixels and cosmic rays, and then the light input will be summed to give the equivalent of a single 3.6 m telescope. A prototype telescope 'PS1' has been constructed, and saw first light using a low-resolution camera in June 2006. The telescope has a 3° field of view, which is extremely large for telescopes of this size, and is equipped with the largest digital camera ever built, recording almost 1.4 billion pixels per image. The focal plane has 60 separately mounted close packed CCDs arranged in an 8 × 8 array. The corner positions are not populated, because the optics do not illuminate the corners. Each CCD device, called an Orthogonal Transfer Array (OTA), has 4800 × 4800 pixels, separated into 64 cells, each of 600 × 600 pixels. This gigapixel camera or 'GPC' saw first light on August 22, 2007, imaging the Andromeda Galaxy.

Each image requires about 2 gigabytes of storage and exposure times will be 30 to 60 seconds (good enough to record objects down to apparent magnitude 24), with an additional minute or so used for computer processing. Since images will be taken on a continuous basis, it is expected that 10 Terabytes of data will be acquired by 'PS4' every night. Because of this very large volume of data, the computer processing will record the positions and magnitudes of all objects in the image after which the image itself will be discarded. Comparing against a database of known unvarying objects compiled from earlier observations will yield objects of interest: anything that has changed brightness and/or position for any reason.

The very large field of view of the telescopes and the short exposure times will enable approximately 6000 square degrees of sky to be imaged every night. The entire sky is 4π steradians, or 4π × (180/π)² ≈ 41,253.0 square degrees, of which about 30,000 square degrees are visible from Hawaii, which means that the entire sky can be imaged in a period of 40 hours (or about 10 hours per night on four days). Given the need to avoid times when the Moon is bright, this means that an area equivalent to the entire sky will be surveyed four times a month, which is entirely unprecedented.
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Science

Systematically surveying the entire sky on a continuous basis is an unprecedented project and is expected to produce a dramatically larger number of discoveries of various types of celestial objects. For instance, the current leading asteroid discovery project LINEAR only goes down to apparent magnitude 19 and concentrates its searches mostly near the ecliptic; Pan-STARRS will go five magnitudes fainter and cover the entire sky visible from Hawaii.
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Solar system

In addition to the large number of expected discoveries in the main asteroid belt, Pan-STARRS is expected to detect at least 100,000 Jupiter Trojan asteroids (compared to 2900 known as of end-2008); at least 20,000 Kuiper belt objects (compared to 800 known as of mid-2005); thousands of Trojan asteroids of Saturn, Uranus and Neptune (currently six Neptune Trojans are known, and none for the other planets excluding Mars and Jupiter); and large numbers of Centaurs and comets.

Apart from drastically adding to the number of known solar system objects, Pan-STARRS will remove or mitigate the observational bias inherent in many current surveys. For instance, among currently known objects there is a bias favoring low orbital inclination, and thus an object such as Makemake escaped detection until recently despite its bright apparent magnitude of 17, which is not much fainter than Pluto. Also, among currently known comets there is a bias favoring those with short perihelion distances. Reducing the effects of this observational bias will enable a more complete picture of solar system dynamics. For instance it is expected that the number of Jupiter Trojans larger than 1 km may in fact roughly match the number of main asteroid belt objects, although the currently known population of the latter is several orders of magnitude larger.

One intriguing possibility is that Pan-STARRS may detect "interstellar debris" or "interstellar interlopers" flying through the solar system. During the formation of a planetary system it is thought that a very large number of objects are ejected due to gravitational interactions with planets (as many as 1013 such objects in the case of our solar system). Objects ejected by planetary systems around other stars might plausibly be flying throughout the galaxy and some may pass through our solar system.

Another intriguing possibility is that Pan-STARRS may actually detect collisions involving small asteroids. These are quite rare and none have yet been observed, but with the drastically larger number of asteroids that will be discovered it is expected from statistical considerations that some collision events may be observed.

Pan-STARRS will also likely detect a number of Kuiper belt objects the size of Pluto or larger, similar to Eris.
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Beyond the solar system

It is expected that Pan-STARRS will discover an extremely large number of variable stars, including such stars in other nearby galaxies; in fact, this may lead to the discovery of hitherto unknown dwarf galaxies. In discovering a large number of Cepheid variables and eclipsing binary stars, it will help determine distances to nearby galaxies with greater precision. It is expected to discover a large number of Type Ia supernovae in other galaxies, which are important in studying the effects of dark energy, and also optical afterglows of gamma ray bursts.

Because very young stars (such as T Tauri stars) are usually variable, Pan-STARRS should discover a large number of these and improve our understanding of them. It is also expected that Pan-STARRS may discover a large number of extrasolar planets by observing their transits across their parent stars, as well as gravitational microlensing events.

Pan-STARRS will also measure proper motion and parallax and should thereby discover a large number of brown dwarfs and white dwarfs and other nearby faint objects, and it should be able to conduct a complete census of all stars within 100 parsecs of the Sun. Prior proper motion and parallax surveys often did not detect faint objects such as the recently-discovered Teegarden's star, which are too faint for projects such as Hipparcos.

Also, by identifying stars with large parallax but very small proper motion for followup radial velocity measurements, Pan-STARRS may even be able to permit the detection of hypothetical Nemesis-type objects if these actually exist.>>

http://en.wikipedia.org/wiki/Large_Synoptic_Survey_Telescope wrote:
<<The Large Synoptic Survey Telescope (LSST) is a planned wide-field "survey" reflecting telescope that will photograph the available sky every three nights. Construction should start in 2010 with first light in 2015. The telescope will be located on the El Peñón peak of Cerro Pachón, a 2682 metre high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

The LSST design is unique among large telescopes (8m-class primary mirrors) in having a very wide field of view: 3.5 degrees in diameter, or 9.6 square degrees. To achieve this very wide undistorted field of view requires three mirrors, rather than the two used by most existing large telescopes: the primary mirror will be 8.4 meters in diameter, the secondary mirror will be 3.4 metres in diameter, and the tertiary mirror, located in a large hole in the primary, will be 5.0 metres in diameter. The large hole reduces the primary mirror's light collecting area to 35 m², equivalent to a 6.68 m diameter circle. A 3.2 gigapixel prime focus digital camera will take a 15-second exposure every 20 seconds.

Allowing for maintenance, bad weather, etc., the camera is expected to take over 200,000 pictures (1.28 petabytes uncompressed) per year, far more than can be reviewed by humans. Managing and effectively data mining the enormous output of the telescope is expected to be the most technically difficult part of the project.

In January, 2008 software billionaires Charles Simonyi and Bill Gates pledged $20 million and $10 million respectively to the project. The project continues to seek a National Science Foundation grant of nearly $400 million.
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Particular scientific goals of the LSST include:

* Measuring weak gravitational lensing in the deep sky to detect signatures of dark energy and dark matter.
* Mapping small objects in the solar system, particularly near-Earth asteroids and Kuiper belt objects.
* Detecting transient optical events such as novae and supernovae.
* Mapping the Milky Way.

It is also hoped that the vast volume of data produced will lead to additional serendipitous discoveries.

Synoptic is an adjective from the same root as the noun "synopsis", and means "relating to data obtained nearly simultaneously over a large area."

Some of the data from the LSST (up to 30 Terabytes per night) will be made available by Google as an up-to-date interactive night-sky map.>>

neufer wrote:Amateurs will still be invaluable for planetary surface changes, I imagine.

tacere wrote:I am not an astronomer, I am just fascinated about stars. A friend told me that you can see clearly Jupiter in the summer sky in the northern emisphere. Is that true? How can I recognize it? Is there a place where I can find easy and intuitive maps of the sky in different seasons!

tacere wrote:I am not an astronomer, I am just fascinated about stars. A friend told me that you can see clearly Jupiter in the summer sky in the northern emisphere. Is that true? How can I recognize it? Is there a place where I can find easy and intuitive maps of the sky in different seasons!

The Planetary Sciences Group at the UPV/EHU-University of the Basque Country with its headquarters at the Faculty of Engineering in Bilbao and led by Professor Agustín Sánchez Lavega, has published the first results of research into the impact of a large-sized celestial body on the planet Jupiter last July.

The work includes researchers from the group Santiago Pérez Hoyos and Ricardo Hueso as well as American scientists, and has appeared in Astrophysical Journal Letters.

According to the studies, the main spot, a very black cloud comprising the waste materials produced by the impact, reached a size of about 5,000 km in the atmosphere of Jupiter, even though it was surrounded by a halo caused by the falling of the material expelled from the atmosphere of up to 8,000 km, slightly smaller than the size of the Earth. It is not known whether the thick cloud consisting of very fine particles (barely a thousandth of a millimetre) and very black, is a product of the waste materials of the object or whether these particles were produced by the extremely high temperatures generated by the impact in Jupiter's atmosphere.

Over the days that followed the ash was blown by Jupiter's winds -which are gentle at these latitudes- in a way similar to the ash being blown from the Icelandic volcano currently erupting. There are doubts as to whether the celestial body that crashed onto the surface of Jupiter was a comet or an asteroid. Assuming that it was of a comet type, -in other words, mainly made up of ice substances-, the size of the meteorite would have been in the region of 500 metres.

• The Astrophysical Journal Letters, 2010 June 01, Vol 715, No 2, L150, doi: 10.1088/2041-8205/715/2/L150

• The Astrophysical Journal Letters, 2010 June 01, Vol 715, No 2, L155, doi: 10.1088/2041-8205/715/2/L155

Without warning, a mystery object struck Jupiter on July 19, 2009, leaving a dark bruise the size of the Pacific Ocean. The spot first caught the eye of an amateur astronomer in Australia, and soon, observatories around the world, including NASA's Hubble Space Telescope, were zeroing in on the unexpected blemish. Astronomers had witnessed this kind of cosmic event before. Similar scars had been left behind during the course of a week in July 1994, when more than 20 pieces of Comet P/Shoemaker-Levy 9 (SL9) plunged into Jupiter's atmosphere. The 2009 impact occurred during the same week, 15 years later.

This Hubble image of Jupiter's full disk, taken July 23, 2009, revealed an elongated, dark spot at lower, right (inside the rectangular box). The unexpected blemish was created when an unknown object plunged into Jupiter and exploded, scattering debris into the giant planet's cloud tops. The strike was equal to the explosion of a few thousand standard nuclear bombs. The series of close-up images at right, taken between July 23, 2009 and Nov. 3, 2009, show the impact site rapidly disappearing. Jupiter's winds also are spreading the debris into intricate swirls. The natural-color images are composites made from separate exposures in blue, green, and red light. Astronomers who compared Hubble images of the two collisions (in 1994 and 2009) say that the culprit in the 2009 event may have been an asteroid about 1,600 feet (500 meters) wide. The images, therefore, may show for the first time the immediate aftermath of an asteroid, rather than a comet, striking another planet.