Monday, November 8, 2010

New Supernova Lights Up Leo



A new supernova? Darn right. Lighting up Leo? Well… not without some serious visual aid, but the fact that someone out there is watching and has invited us along for the ride is mighty important. And just who might that someone be? None other than Tim Puckett.
Less than 24 hours ago, the American Association of Variable Star Observer’s Report #222 stated:
“Bright Supernova in UGC 5189A: SN 2010jl
November 5, 2010
We have been informed by Tim Puckett and by the Central Bureau for Astronomical Telegrams (CBET 2532, Daniel W. E. Green, Ed.) of the discovery of a bright supernova in UGC 5189A by J. Newton and Puckett, Portal, AZ, on November 3.52 UT at unfiltered magnitude 13.5. Confirming images (limiting magnitude 19.1) by Puckett on Nov. 4.50 UT showed the object at magnitude 12.9.
Spectroscopic observations (CBET 2536, Daniel W. E. Green, Ed.) by S. Benetti and F. Bufano, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, on behalf of a larger collaboration, and by J. Vinko, University of Szeged, G. H. Marion, Harvard-Smithsonian Center for Astrophysics and University of Texas, T. Pritchard, Pennsylvania State University, and J. C. Wheeler and E. Chatzopoulos, University of Texas, show that SN 2010jl is a type-IIn supernova. Vinko et al. also report that simultaneous measurements with Swift/UVOT in the ultraviolet bands confirm that the transient is ultraviolet-bright, as expected for young, interacting supernovae.
Coordinates: 09 42 53.33 +09 29 41.8 (J2000.0) This position is 2.4″ east and 7.7″ north of the center of UGC 5189A. This AAVSO Special Notice was prepared by Elizabeth O. Waagen.”

While magnitude 12-12.9 isn’t unaided eye bright by a long shot, it’s well within the reach of most of today’s backyard telescopes. The image you see here on the right is of UGC 5189A before the event and the lefthand image was taken at the time of the supernova report. Visually the SN event outshines the galaxy! While chasing a faint supernova event might not be everyone’s cup of tea, Mr. Puckett’s devotion is absolutely legendary and I strongly encourage you to have a look if you have the the tools and talent.
So many supernovae… So little time!

Thursday, September 30, 2010

New Earth-sized Exoplanet is in Star’s Habitable Zone


Artist illustration of a super Earth around Gliese 581
An enticing new extrasolar planet found using the Keck Observatory in Hawaii is just three times the mass of Earth and it orbits the parent star squarely in the middle of the star’s “Goldilocks zone,” a potential habitable region where liquid water could exist on the planet‘s surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one. The discoverers also say this finding could mean our galaxy may be teeming with prospective habitable planets.

“Our findings offer a very compelling case for a potentially habitable planet,” said Steven Vogt from UC Santa Cruz. “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.”
Vogt and his team from the Lick-Carnegie Exoplanet Survey actually found two new planets around the heavily studied red dwarf star Gliese 581, where planets have been found previously. Now with six known planets, Gliese 581 hosts a planetary system most similar to our own. It is located 20 light years away from Earth in the constellation Libra.
The most interesting of the two new planets is Gliese 581g, with a mass three to four times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with likely enough gravity to hold on to an atmosphere.
The planet is also tidally locked to the star, meaning that one side is always facing the star in sunlight, while the side facing away from the star is in perpetual darkness. One effect of this is to stabilize the planet’s surface climates, according to Vogt. The most habitable zone on the planet’s surface would be on the terminator, the line between shadow and light, with surface temperatures decreasing toward the dark side and increasing toward the light side.
“Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude,” Vogt said.
There has been debate about the other planets found previously around Gliese 581, whether they could be habitable or not. Two of them lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly discovered planet g, however, lies right in the middle of the habitable zone.
“We had planets on both sides of the habitable zone–one too hot and one too cold–and now we have one in the middle that’s just right,” Vogt said.
The researchers estimate that the average surface temperature of the planet is between -24 and 10 degrees Fahrenheit (-31 to -12 degrees Celsius). Actual temperatures would range from blazing hot on the side facing the star to freezing cold on the dark side.
If Gliese 581g has a rocky composition similar to the Earth’s, its diameter would be about 1.2 to 1.4 times that of the Earth. The surface gravity would be about the same or slightly higher than Earth’s, so that a person could easily walk upright on the planet, Vogt said.
The planet was found using the HIRES spectrometer (designed by Vogt) on the Keck I Telescope, measuring the star’s radial velocity. The gravitational tug of an orbiting planet causes periodic changes in the radial velocity of the host star. Multiple planets induce complex wobbles in the star’s motion, and astronomers use sophisticated analyses to detect planets and determine their orbits and masses.
“It’s really hard to detect a planet like this,” Vogt said. “Every time we measure the radial velocity, that’s an evening on the telescope, and it took more than 200 observations with a precision of about 1.6 meters per second to detect this planet.”
In addition to the radial velocity observations, coauthors Henry and Williamson made precise night-to-night brightness measurements of the star with one of Tennessee State University’s robotic telescopes. “Our brightness measurements verify that the radial velocity variations are caused by the new orbiting planet and not by any process within the star itself,” Henry said.
The researchers also explored the implications of this discovery with respect to the number of stars that are likely to have at least one potentially habitable planet. Given the relatively small number of stars that have been carefully monitored by planet hunters, this discovery has come surprisingly soon.
“If these are rare, we shouldn’t have found one so quickly and so nearby,” Vogt said. “The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky Way, that’s a large number. There could be tens of billions of these systems in our galaxy.”
Source: University of California – Santa Cruz

Wednesday, September 29, 2010

ASTRONOMICAL EVENTS FOR OCTOBER 2010





Oct 1: Comet 103P Hartley is just 1 deg 37’ from Alpha Cassiopeia

Oct 1: Saturn Conjunction

Oct 1: Last Quarter Moon

Oct 5: A Waning Crescent Moon stands within 6 degrees from Regulus in East just before dawn

Oct 7: Mars is just 41’25” from a 2.7th mag star Alpha Librae after sunset in West

Oct 7: Comet 103P Hartley is just 1.5 deg away from “Double Clusters” in Perseus. Great opportunity for astro-photographers!!

Oct 8: New Moon

Oct 8-9: Draconids Meteor Shower will peak in a New Moon night. Expect a peak rate of 10 meteors per hour under clear, moonless conditions.

Oct 11: A Waxing Crescent Moon is just 2 degrees from Antares in West at the time of evening

Oct 15: First Quarter Moon

Oct 17: Mercury Superior Conjunction

Oct 18: Comet 103P Hartley is within 3 degrees south of brilliant Capella

Oct 20: The Moon is within 8 degrees from Jupiter

Oct 20: Comet 103P Hartley is closest to Earth by distance of 0.12 AU.

Oct 21-22: Orionids Meteor Shower will peak in presence of a Waxing Gibbous (95% illuminated) Moon. This shower produces a peak rate of 20 meteors per hour.

Oct 23: Comet 103P Hartley is just 1.5 deg from the Open Cluster M37 after midnight

Oct 23: Full Moon

Oct 25: The Moon is just about 4 degrees from M45

Oct 26: Comet 103P Hartley is 3 degrees from a rich open cluster M35 in Gemini after midnight

Oct 29: Venus Inferior Conjunction

Oct 30: Last Quarter Moon



THIS MONTH’S PLANET ROUND-UP


VENUS: Very low in the evening sky. The planet will be on Inferior Conjunction on 29th October.

MARS: Along with Venus, Mars is very low in the evening sky at West. Mars will be just 41’25” from a 2.7th mag star Alpha Librae on 7th.

JUPITER: Jupiter will be visible for most of the time of night during October. The planet URANUS will remain close with Jupiter.

SATURN: The ringed world will emerge from the early morning eastern sky around 20th August. The planet will be very close to Gamma Virginis star.

MERCURY: Mercury will be on Superior Conjunction on 17th.

Friday, September 3, 2010

Supernova Spews Its Guts Across Space


The recently refurbished Hubble Space Telescope has taken a new look at Supernova 1987A and its famous "String of Pearls," a glowing ring 6 trillion miles in diameter encircling the supernova remnant. The sharper and clearer images are allowing astronomers to see the “innards” of the star being ejected into space following the explosion, and comparing the new images with ones taken previously provides a unique glimpse of a young supernova remnant as it evolves. They found significant brightening of the object over time, and also evident is how the shock wave from the star’s explosion has expanded and rebounded.

Kevin France from the University of Colorado Boulder and colleagues compared the new Hubble data on the SN1987A taken in 2010 with older images, and observed the supernova in optical, ultraviolet and near-infrared light. They were able to look at the interplay between the stellar explosion and the 'String of Pearls' that encircles the supernova remnant. The gas ring — energized by X-rays — likely was spewed out about 20,000 years before the supernova exploded, and shock waves rushing out from the remnant have been brightening some 30 to 40 pearl-like "hot spots" in the ring — objects that likely will grow and merge together in the coming years to form a continuous, glowing circle.

Ultraluminous Gamma Ray Burst 080607 – A "Monster in the Dark"

Shedding Light on Dark Gamma Ray Bursts

Gamma Ray Bursts (GRBs) are among the most energetic phenomena astronomers regularly observe. These events are triggered by massive explosions and a large amount of the energy if focused into narrow beams that sweep across the universe. These beams are so tightly concentrated that they can be seen across the visible universe and allow astronomers to probe the universe's history. If such an event happened in our galaxy and we stood in the path of the beam, the effects would be pronounced and may lead to large extinctions. Yet one of the most energetic GRBs on record (GRB 080607) was shrouded in cloud of gas and dust dimming the blast by a factor of 20 – 200, depending on the wavelength.  Despite this strong veil, the GRB was still bright enough to be detected by small optical telescopes for over an hour. So what can this hidden monster tell astronomers about ancient galaxies and GRBs in general?
GRB 080607 was discovered on June 6, 2008 by the Swift satellite. Since GRBs are short lived events, searches for them are automated and upon detection, the Swift satellite immediately oriented itself towards the source. Other GRB hunting satellites quickly joined in and ground based observatories, including ROTSE-III and Keck made observations as well. This large collection of instruments allowed astronomers, led by D. A. Perley of UC Berkley, to develop a strong understanding of not just the GRB, but also the obscuring gas. Given that the host galaxy lies at a distance of over 4 billion light years, this has provided a unique probe into the nature of the environment of such distant galaxies.
One of the most surprising features was unusually strong absorption near 2175 °A. Although such absorption has been noticed in other galaxies, it has been rare in galaxies at such large cosmological distances. In the local universe, this feature seems to be most common in dynamically stable galaxies but tends to be "absent in more disturbed locations such as the SMC, nearby starburst galaxies" as well as some regions of the Milky Way which more turbulence is present. The team uses this feature to imply that the host galaxy was stable as well. Although this feature is familiar in nearby galaxies, observing it in this case makes it the furthest known example of this phenomenon. The precise cause of this feature is not yet known, although other studies have indicated "polycyclic aromatic hydrocarbons and graphite" are possible suspects.
Earlier studies of this event have shown other novel spectral features. A paper by Sheffer et al. notes that the spectrum also revealed molecular hydrogen. Again, such a feature is common in the local universe and many other galaxies, but never before has such an observation been made linked to a galaxy in which a GRB has occurred. Molecular hydrogen (as well as other molecular compounds) become disassociated at high temperatures like the ones in galaxies containing large amounts of star formation that would produce regions with large stars capable of triggering GRBs. With observations of one molecule in hand, this lead Sheffer's team to suspect that there might be large amounts of other molecules, such as carbon monoxide (CO). This too was detected making yet another first for the odd environment of a GRB host.
This unusual environment may help to explain a class of GRBs known as "subluminous optical bursts" or "dark bursts" in which the optical component of the burst (especially the afterglow) is less bright than would be predicted by comparison to more traditional GRBs.
Sources:
Monster in the Dark: The Ultra Luminous GRB 080706 and its Dusty Environment
The Discovery of Vibrationally-Excited H2 In the Molecular Cloud Near GRB 080706

Wednesday, September 1, 2010

Sky Calender for September




ASTRONOMICAL EVENTS FOR SEPTEMBER 2010

Sept 1: The Moon is nearly 2 degrees SW of Pleiades after midnight

Sept 1: Venus is just 1 degree SW of Spica in the west after sunset

Sept 2: The Moon is within 8 degrees North of Aldebaran

Sept 3: Mercury Inferior Conjunction

Sept 8: New Moon

Sept 11: A Waxing Crescent Moon (only 14% illuminated) is just 1 degree away from bright Venus at 8:00pm in the western sky


Sept 14: The Moon stands within 4.5 degrees from Antares

Sept 15: First Quarter Moon

Sept 19: Mercury Greatest Western Elongation

Sept 21: Both Jupiter (Angular dia. 50 arc sec) and Uranus (Angular dia. 3.7 arc sec) are at opposition. Both the planets will be just 49’35” apart in the constellation Pisces.

Sept 23: Full Moon

Sept 28: The Moon and Pleiades are 5.5 degrees apart



SEPTEMBER 2010 PLANET ROUND-UP

Saturn: Very low in the western evening sky and will be lost in the glare of sun after mid September.

Mars: In the western evening sky in the constellation Virgo. The planet shines at mag. 1.5. The planet will be nearly 2 degrees from Spica on 5th.

Venus: The brightest light in the western evening sky for the whole month. On 1st September the planet will be just 1 degree from Spica. On 11th the planet will be again 1 degree from beautiful Crescent Moon making a lovely scene fits in almost any wide-field instrument.

Neptune: Shines at mag. 7.8 throughout the month in the constellation Capricornus.
Jupiter & Uranus: Both planets will be at opposition on September 21st and will be just 49’35” apart at that time. It will be great opportunity to see both planets together in one field of view when both are at opposition.

Mercury: The planet will emerge from the eastern morning sky around 10th September. Mercury will be at greatest Western Elongation on 19th. At that time the planet will be 18 degrees from sun.

Saturday, August 28, 2010

Weird Crater on Mars is a Mystery

Orcus Patera is an enigmatic elliptical depression. Credits: ESA/DLR/FU Berlin (G. Neukum
This is one of the strangest looking craters ever found on Mars, and this platypus-tail-shaped depression, called Orcus Patera, is an enigma. The term ‘patera’ is used for complex or irregularly shaped volcanic craters, but planetary scientists aren’t sure if this landform is volcanic in origin. Orcus Patera lies between the volcanoes of Elysium Mons and Olympus Mons, but its formation remains a mystery. This is the latest image of the object, taken by ESA’s Mars Express.

It could be an impact crater that originally was round, but then subsequently deformed by compressional forces. Or, it could have formed from two craters next to each where the adjoining rims eroded. However, the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle.


Relief image of Orcus Patera. Credit: ESA/DLR/FU Berlin (G. Neukum)
It is 380 km long by by 140 km wide, and has a rim that rises up to 1,800 meters above the surrounding plains, while the floor of the depression lies 400–600 m below the surroundings. The floor of the depression is unusually smooth.
The image above was created using a Digital Terrain Model (DTM) obtained from the High Resolution Stereo Camera on ESA’s Mars Express spacecraft. Elevation data from the DTM are color-coded: purple indicates the lowest-lying regions, and beige the higher elevations. The scale is in meters.
Source: ESA

Watch Titan Occult a Binary Star System

Titan passing in front of the binary star system named NV0435215+200905. Credit: Palomar Observator
Scott Kardel from the Palomar Observatory just posted something extremely cool on his Palomar Skies website. Back in 2001, a group of astronomers used the 200-inch Hale Telescope equipped with adaptive optics to observe Saturn's moon Titan pass in front of a binary star system. The two stars are separated in the sky by just 1.5 arc seconds, but because of the fantastic resolving power of the Hale and its adaptive optics, visible in the image above is the light of the star nearest to Titan being refracted by Titan's dense atmosphere. As Scott said, such events are rare but valuable. Mike Brown (of Eris fame) was among the astronomers and on Twitter today, he linked to a video the team created from their observations, which is just awesome. Not only did they see the occultation, but they also found out that Titan has jet stream-like winds in its atmosphere. Watch the movie, (or see below, someone has now YouTubed it) and then read their paper about the event! 

Thursday, August 19, 2010

Massive Mega-Star Challenges Black Hole Theories

Astronomers have discovered a massive star that once dwarfed our sun and is now challenging theories of how stars evolve, die and form black holes.



The star is a peculiar cosmic object known as a magnetar. Magnetars are extremely dense, super-magnetic stars that can form from supernova explosions.

The newly discovered magnetar is perplexing, because astronomers have calculated that its progenitor likely weighed at least 40 times as much as the sun. Large stars in this mass category are thought to become black holes, not magnetars, when they explode in supernovas.

"This therefore raises the thorny question of just how massive a star has to be to collapse to form a black hole if stars over 40 times as heavy as our sun cannot manage this feat," said researcher Norbert Langer of the Universit├Ąt Bonn in Germany and the Universiteit Utrecht in the Netherlands.

When massive stars reach the end of their lives and die in supernovas, they leave behind remnants. If the star is very massive, that remnant is a black hole – an extremely dense collection of mass with such a strong gravitational pull, not even light can escape.

If the original star was slightly less massive, the supernova remnant will become a neutron star. These objects, made of mostly neutrons, are more dense than a regular star but less dense than a black hole.

Magnetars are a type of neutron star with colossal magnetic fields that are about a million billion times stronger than that of Earth.

Perplexing magnetic star

This unusual magnetar star was discovered in the star cluster Westerlund 1, located 16,000 light-years away in the southern constellation of Ara (the Altar).

This special clump of hundreds of massive stars was formed in a single event, which means that all its stars are roughly the same age – between 3.5 and 5 million years old.

The age and characteristics of the cluster allowed astronomers to estimate the mass of the magnetar, which is one of only a few magnetars known in the Milky Way. Its mass puts it well within the range expected to create a black hole.

How massive stars die

Scientists have thought that stars with initial masses between about 10 and 25 suns would form neutron stars when they die, while stars above 25 times that of the sun would produce black holes.

The researchers think the magnetar in question must have lost much of its mass before it died to have ended up the way it did.

"These stars must get rid of more than nine tenths of their mass before exploding as a supernova, or they would otherwise have created a black hole instead," said researcher Ignacio Negueruela of the Universidad de Alicante in Spain. "Such huge mass losses before the explosion present great challenges to current theories of stellar evolution."

The researchers observed the magnetar with the European Southern Observatory's Very Large Telescope in Chile. They detailed their findings in a paper to be published in an upcoming issue of the journal Astronomy and Astrophysics.

Friday, August 6, 2010

Space Telescopes Team Up to Capture Spectacular Galactic Collision

A new image of two tangled galaxies has been released by NASA's Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red). The Antennae galaxies take their name from the long antenna-like arms seen in wide-angle views of the system. These features were produced in the collision. Image credit: Chandra: NASA/CXC/SAO, Spitzer: NASA/JPL-Caltech, Hubble: NASA/STScI
From JPL:
A new image of two tangled galaxies has been released by NASA's Great Observatories. The Antennae galaxies, located about 62 million light-years from Earth, are shown in this composite image from the Chandra X-ray Observatory (blue), the Hubble Space Telescope (gold and brown), and the Spitzer Space Telescope (red). The Antennae galaxies take their name from the long, antenna-like arms seen in wide-angle views of the system. These features were produced in the collision.

The collision, which began more than 100 million years ago and is still occurring, has triggered the formation of millions of stars in clouds of dusts and gas in the galaxies. The most massive of these young stars have already sped through their evolution in a few million years and exploded as supernovas.
The X-ray image from Chandra shows huge clouds of hot, interstellar gas, which have been injected with rich deposits of elements from supernova explosions. This enriched gas, which includes elements such as oxygen, iron, magnesium and silicon, will be incorporated into new generations of stars and planets. The bright, point-like sources in the image are produced by material falling onto black holes and neutron stars that are remnants of the massive stars. Some of these black holes may have masses that are almost one hundred times that of the sun.
The Spitzer data show infrared light from warm dust clouds that have been heated by newborn stars, with the brightest clouds lying in the overlap region between the two galaxies. The Hubble data reveal old stars and star-forming regions in gold and white, while filaments of dust appear in brown. Many of the fainter objects in the optical image are clusters containing thousands of stars.

Thursday, August 5, 2010

Aurora Alert! Solar Storm Reaches Earth


 Finally, some excitement from the Sun! On August 1, 2010, the entire Earth-facing side of the sun erupted with all sorts of activity. There was a C3-class solar flare, a solar tsunami, multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection (CME) and more. (Watch the movie from the Solar Dynamics Observatory spacecraft for all the action!) As I write this, the solar storm is beginning to reach Earth with one, and possibly two CMEs, according to Spaceweather.com. You can actually watch realtime data coming in from two of the GOES satellites at this link from NOAA's Space Weather Prediction Center, which measures proton flux in the space environment around Earth. The page refreshes every 5 minutes.

NOAA forecasters are estimating a 10% chance of major geomagnetic storms and a 45% chance of at least some geomagnetic activity when the clouds arrive on August 3rd and 4th, so those of you in the northern latitudes should be on the lookout for aurorae on both August 3 and 4.
Readers, anyone who captures aurorae images, send them in to Nancy
This has been an unusually quiet solar cycle. We are heading towards a solar max in three years which is on track to be just over half as intense as the last one in 2001, and the lowest in over 100 years.

Wednesday, August 4, 2010

Astronomical Calender for August 2010

August 1: A Waning Gibbous Moon stands 11 degrees N-NE of Jupiter after midnight.Mars and Saturn are nearly 2 degrees apart in West just after sunset.
August 3: Last Quarter Moon.
August 5: The Moon (32% illuminated) stands within 4 degrees from Pleiades (M45) in east before dawn.Venus-Saturn-Mars forms a perfect triangle in West at the time of dusk. The triangle will barely fit within standard 10×50 binoculars.
August 7: Mercury Greatest Eastern Elongation.
August 8: Venus and Saturn within 3 degrees apart after sunset in West.
August 10: New Moon.
August 12-13: The Perseids Meteor Shower will peak in a “moon-free” night!
August 13: Accumulation of a very thin Crescent Moon joining a beautiful trio of Venus, Saturn and Mars in the West after sunset.

Don’t miss to watch beautiful accumulation of a very thin Crescent Moon joining a beautiful trio of Venus, Saturn and Mars in the West after sunset.
August 14: A Waxing Crescent Moon is within 4 degrees from Spica at dusk in the West.
August 16: First Quarter Moon.
August 17: The Moon is within 5 degrees West of Antares at the time of dusk.
August 18: Venus and Mars are about 2 degrees apart and Venus’ Greatest Eastern Elongation.
August 20: Neptune is at opposition, Mag. 7.8 in the constellation Capricornus.
August 24: Full Moon.
August 26: The Moon is around 8.5 degrees from Jupiter.
August 31: Venus is nearly 1 degree W-SW of Spica at 8:00pm in West.

THIS MONTH’S PLANET ROUND-UP

MERCURY: Mercury is very low in the West during this month. The inner-most planet will be at greatest elongation on 7th August.
VENUS: Venus will remain in group with Saturn and Mars through out the month. The brightest planet will provide beautiful show with Mars and Saturn in the Western evening sky after sunset. Venus is at greatest elongation on 18th August. Venus will pass very close from Saturn on 8th August and will pass very close from Mars on 19th. On August 31st, the planet will be just 1 degree from Spica.
SATURN & MARS: Both planets will remain in group with Venus throughout the month. On August 1st, both will be placed within 2 degrees from each other. On August 13th a Crescent Moon will join them.
NEPTUNE: The planet will enter the constellation Capricornus on 14th August. This month is a good time to observe Neptune as it is near opposition on August 20th. The planet will show an angular disc of 2.4” and will shine at magnitude 7.8th.
JUPITER & URANUS: Both planets are in Pisces. Both will be nearly 3 degrees from each other and will get closer and closer during month.


This Month Sky Chart

Tuesday, August 3, 2010

Get Ready for the Perseids: Join the World in Watching


This year's Perseid meteor shower on August 11-14 is predicted to be one of the best in recent years, and if this awesome trailer from "MeteorWatch" organizer Adrian West doesn't get you excited, then nothing will! Who knew meteors could be such a heart-pumping thrill ride! If you haven't heard of MeteorWatch, it is a way to watch the shower with others, and share your experiences even if you are out there watching all alone. This is a social media astronomical event that has been a big hit among Twitterers for previous events. But there's lots of ways to join in, not only on Twitter (hashtage is #meteorwatch). Everyone is welcome whether they are an astronomer or just have an interest in the night sky. The aim is to get as many people to look up as possible and maybe see meteors or even some fireballs for the first time. Here are a few additional resources:

1) a dedicated website with a "live" Twitter page
2) a handy Twitter observation reporting system, (still being coded, so check the website out as the Perseids approach) to map and archive international meteor counts, etc.
3) live AstronomyFM (AFM) Radio updates from the Under British Skies crew in England, with possible updates from other places around the world.
4) Meteorwatch is also on Facebook
Tavi Greiner from "A Sky Full of Stars" has some fun Perseid facts, as well as some tips for planning for the Perseids.

And if it is cloudy where you are for the Perseids, you can always try listening for meteor "pings" via radio. Its very cool and fun, too.

Radar Images Reveal Tons of Water Likely at the Lunar Poles

Radar has been used since the 1960s to map the lunar surface, but until recently it has been difficult to get a good look at the Moon's poles. In 2009, the Mini-SAR radar instrument on the Chandrayaan-1 spacecraft was able to map more than 95% of both poles at 150 meter radar resolution, and now the Mini-RF instrument on the Lunar Reconnaissance Orbiter — which has 10 times the resolution of the Mini-SAR — is about halfway through its first high-resolution mapping campaign of the poles. The two instruments are revealing there are likely massive amounts of water in the permanently shadowed craters at the poles, with over 600 million metric tons at the north pole alone. "If that was turned into rocket fuel, it would be enough to launch the equivalent of one Space Shuttle per day for over 2,000 years," said Paul Spudis, principal investigator for the Mini-SAR, speaking at the annual Lunar Forum at the Ames Research Center in July.

Both Spudis and Ben Bussey, principal investigator for LRO's Mini-RF shared images from their respective instruments at the Forum, highlighting polar craters that exhibit unusual radar properties consistent with the presence of ice.
They have found over 40 craters on the Moon's north pole that exhibit these properties.
Both instruments provide details of the interior of shadowed craters, not able to be seen in visible light. In particular, a measurement called the circular polarization ratio (CPR) shows the characteristics of the radar echoes, which give clues to the nature of the surface materials in dark areas. The instruments send pulses of left-polarized radio waves to measure the surface roughness of the Moon. While smooth surfaces send back a reversed, right-polarized wave, rough areas return left-polarized waves. Ice, which is transparent to radio waves, also sends back left-polarized waves. The instruments measure the ratio of left to right circular polarized power sent back, which is the CPR.
Few places – even in our solar system — have a CPR greater than 1 but such places have thick deposits of ice, such as Martian polar caps, or the icy Galilean satellites. They are also seen in rough, rocky ejecta around fresh, young craters, but there, scientists also observe high CPR outside the crater rim such as in this image, below of the Main L crater on the Moon.
The fresh impact crater Main L (14 km diameter), which shows high CPR inside and outside its rim. The histograms at right show that the high CPR values within (red line) and outside the crater rim (green line) are nearly identical. Credit: NASA
Most of the Moon has low CPR, but dozens of anomalous north pole craters, such as a small 8 km crater within the larger Rozhdestvensky crater, had a high CPR on the inside, with a low CPR on the rims. That suggests some material within the craters, rather than surface roughness, caused the high CPR signal.
"Geologically, we don't expect rough, fresh surfaces to be present inside a crater rim but absent outside of it," Spudis said. "This confirms the high CPR in these anomalous craters is not caused by surface roughness, and we interpret this to mean that water ice is present in these craters."
An “anomalous” crater on the floor of Rozhdestvensky, near the north pole of the Moon. The histogram of CPR values clearly shows that interior points (red line) have higher CPR values than those outside the crater rim (green line). Credit: NASA

Additionally, the ice would have to be several meters thick to give this signature. "To see this elevated CPR effect, the ice must have a thickness on the order of tens of wavelengths of the radar used," he said. "Our radar wavelength is 12.6 cm, therefore we think that the ice must be at least two meters thick and relatively pure."Recent Mini-SAR images (top image) from LRO confirm the Chandrayaan-1 data, with even better resolution. The Mini-RF, Bussey said, is equivalent to a combination of the Arecibo Observatory and the Greenbank Radio telescope in looking at the Moon. "Our polar campaign will map from 70 degrees to the poles and so far we are very pleased with the coverage and quality of the data," Bussey said.
Spudis said they are seeing less anamolous craters on the Moon's south pole, but both he and Bussey are looking forward to comparing more data between the two radar instruments to learn more about the permanently shadowed craters on the Moon.
Additionally, other instruments on LRO will also provide insights into the makeup of these anomalous craters