The Pithy Amateur Astronomer

The Galileo craft is long since departed from our presence but that doesn't mean much can't be learned.

I was browsing through the NASA site and found some sounds that the spacecraft recorded. I recommend this as something to listen to. The sounds are haunting and mesmerizing.

http://www2.jpl.nasa.gov/galileo/sounds.html

Source: http://science.nasa.gov/science-news/science-at-nasa/2010/18jun_newhorizons/

The probe New Horizons wakes up for a bit of instrument testing. I am very anxious to see the findings this probe will come up with for Pluto and other Kuiper belt objects (KBO).

This is the fastest probe ever launched, traveling 1 million miles a day. The solar system is so vast that it will take another 5 years for the probe to reach its destination.

APOD (Astronomy Picture of the Day) turns 15 today! I remember being 15 and it was...well...just weird...

But I digress. APOD is one of the many sources I use to share my favorite pictures. Todays picture is no exception. It is a nice collection of various astronomy pictures to recreate Vermeer's Astronomer and Geographer.

Thanks and keep up the good work!

Source: http://antwrp.gsfc.nasa.gov/apod/ap100616.html

Explanation: Welcome to the quindecennial year of the Astronomy Picture of the Day! Perhaps a source of web consistency for some, APOD is still here. As during each of the 15 years of selecting images, writing text, and editing the APOD web pages, the occasionally industrious Robert Nemiroff (left) and frequently persistent Jerry Bonnell (right) are pictured above plotting to highlight yet another unsuspecting image of our cosmos. Although the above image may appear similar to the whimsical Vermeer composite that ran on APOD's fifth anniversary, a perceptive eye might catch that this year it has been digitally re-pixelated using many of the over 5,000 APOD images that have appeared over APOD's tenure. (Can you find any notable APOD images?) Once again, we at APOD would like to offer a sincere thank you to our readership for continued interest, support, and many gracious communications.

Source: http://antwrp.gsfc.nasa.gov/apod/ap100609.html

Explanation: Even a quiet Sun can be a busy place. And over the deep Solar Minimum of the past few years, our Sun has been unusually quiet. The above image, taken last week in a single color of light called Hydrogen Alpha and then false colored, records a great amount of detail of the simmering surface of our parent star. The gradual brightening towards the Sun's edge in this color-inverted image, called limb darkening, is caused by increased absorption of relatively cool solar gas. Just over the Sun's edges, several prominences are visible, while two prominences on the Sun's face are seen as light streaks just above and right of the image center. Two particularly active areas of the Sun are marked by dark plages. In contrast to recent quiet times, our Sun is moving toward Solar Maximum, and for years will likely appear much more active.

A friend of mine said it looks like the yellow part of an egg...now I'm hungry for some fried eggs!

 Source http://antwrp.gsfc.nasa.gov/apod/ap100607.html

Explanation: A new comet is brightening and is now expected to become visible to the unaided eye later this month. C/2009 R1 (McNaught) is already showing an impressive tail and is currently visible through binoculars. The above image, taken yesterday from the Altamira Observatory in the Canary Islands and spanning about five degrees, shows an impressive green coma and a long ion tail in front of distant star trails. Although predicting the brightness of comets is notoriously difficult, current estimates place Comet McNaught as becoming visible to unaided northern hemisphere observers in late June, before sunrise, and in early July, after sunset. Discovered by Robert McNaught last year, the sun-orbiting iceberg will pass the Earth next week and will continue to melt and shed debris as it closes in on the Sun until early July. After reaching about half of the Earth-Sun distance from the Sun, the comet should fade rapidly as it then heads out of the inner Solar System.

Going against the grain may turn out to be a powerful move for black holes. New research suggests supermassive black holes that spin backwards might produce more ferocious jets of gas. The results have broad implications for how galaxies change over time.

"A lot of what happens in an entire galaxy depends on what's going on in the miniscule central region where the black hole lies," said David Garofalo of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Black holes are immense distortions of space and time with gravity that is so great, even light itself cannot escape. Astronomers have known for more than a decade that all galaxies, including our own Milky Way, are anchored by tremendous supermassive black holes containing billions of Suns' worth of mass. The black holes are surrounded and nourished by disks of gas and dust called accretion disks. Powerful jets stream out from below and above the disks like lasers, and fierce winds blow off from the disks themselves.

The black holes can spin either in the same direction as the disks — prograde black holes — or against the flow — the retrograde black holes. For decades, astronomers thought that the faster the spin of the black hole, the more powerful the jet. But there were problems with this "spin paradigm" model. For example, scientists found some prograde black holes with no jets.

Garofalo and his colleagues have been busy flipping the model on its head. In previous papers, they proposed that the backward, or retrograde, black holes spew the most powerful jets, while the prograde black holes have weaker or no jets.

The new study links the researchers' theory with observations of galaxies across time or at varying distances from Earth. They looked at both "radio-loud" galaxies with jets and "radio-quiet" ones with weak or no jets. The term "radio" comes from the fact that these particular jets shoot out beams of light mostly in the form of radio waves.

The results showed that more distant radio-loud galaxies are powered by retrograde black holes, while relatively closer radio-quiet objects have prograde black holes. According to the team, the supermassive black holes evolve over time from a retrograde to a prograde state.

"This new model also solves a paradox in the old spin paradigm," said David Meier at JPL, who is not involved in the study. "Everything now fits nicely into place."

The scientists say that the backward black holes shoot more powerful jets because there's more space between the black hole and the inner edge of the orbiting disk. This gap provides more room for the build-up of magnetic fields that fuel the jets, an idea known as the Reynolds conjecture after the theoretical astrophysicist Chris Reynolds of the University of Maryland, College Park.

"If you picture yourself trying to get closer to a fan, you can imagine that moving in the same rotational direction as the fan would make things easier," said Garofalo. "The same principle applies to these black holes. The material orbiting around them in a disk will get closer to the ones that are spinning in the same direction versus the ones spinning the opposite way."

Jets and winds play key roles in shaping the fate of galaxies. Some research shows that jets can slow and even prevent the formation of stars not just in a host galaxy itself, but also in other nearby galaxies.

"Jets transport huge amounts of energy to the outskirts of galaxies, displace large volumes of the intergalactic gas, and act as feedback agents between the galaxy's very center and the large-scale environment," said Rita Sambruna of NASA Goddard Space Flight Center, Greenbelt, Maryland. "Understanding their origin is of paramount interest in modern astrophysics."

Article Source: http://www.astronomy.com/asy/default.aspx?c=a&id=9915