February 21, 2020

July 08 News & Notes.

Attack of the Plutoids? On June 11th, the International Astronomical Union (IAU) handed down yet another definition for trans-Neptunian objects; a new class of planetary bodies, now classified as Plutoids, have sprung into existence.

Plutoids are defined as “Celestial bodies in orbit around the sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume hydrostatic equilibrium (i.e. a fancy way to say they’re round), and have not cleared their orbit. Under this new definition, Pluto and Eris qualify; their respective moons of Charon and Dysnomia do not. Doubtless, more Plutoids will be discovered as time goes on. Alas, poor Ceres is now in a dwarf planet class of its own! What’s next, Ceroids?

Mars Phoenix Lander Update: Ah, how the data has come streaming in! Mars Phoenix has proven to be wildly successful streaming in a wealth of telemetry this past June. Images have also revealed that the retro rockets have uncovered what appears to be ice exposed directly beneath the lander. What’s different in the two images above? Note the disappearance of the whitish material exposed by the scoop arm. Scientists think that this may be evidence of frozen water sublimating as it is exposed. The atmospheric pressure is so low on Mars, that frozen water simply boils away! While water isn’t an indicator that life must exist on Mars, as much of the media has touted, we on Earth have yet to envision life without it!

Large Binocular Telescope Update: The world’s largest interferometer telescope saw first light recently. The Large Binocular Telescope (LBT) on Mount Graham near Portal, Arizona sports two 8.4 meter mirrors spaced 22.8 meters apart that focus light into an interference pattern. This will give it an effective resolution equivalent to the mirror spacing. The LBT first began construction in 1996, and has faced problems with environmentalists and construction delays. The LBT promises to revolutionize our knowledge of extra-galactic astronomy as well as discover new exo-planets.

An Iron Snow? It has been known since the first Mariner 10 flybys of Mercury in the 1970′s that the planet Mercury has a weak but discernable magnetic field. Now researchers form the University of Illinois believe that iron is “precipitating” deep within the core of the planet. This convection could account for the feeble magnetic field. Mercury’s magnetism is about 1 percent that of Earths’. Future flybys by the Messenger space probe, which will also enter orbit in 2013, will shed light on the issue.

Hubble Servicing Update: One of the most anticipated shuttle missions this year is the on again, off again, final servicing mission to the Hubble Space Telescope (HST). First launched in 1990, the Hubble has delivered unprecedented imagery and expanded our view of the cosmos, as well as been on hand to witness the impact of Shoemaker-Levy 9 on Jupiter. Now STS-125, the mission that’s slated to fly the final servicing mission to Hubble, has been slipped to late September or early October. The delay is due to the fact that Hubble lies in a different, higher orbit than the International Space Station; a second shuttle must be prepared to back up the Atlantis in the event of an emergency rescue.  Hubble is down to one serviceable gyro out of four, and a final failure would leave it dead in space. Its successor, the James Webb Telescope, is not scheduled for launch until 2013. 

The Farthest Aphelion: Feeling a little toasty this summer? Ironically, July 4th marks one of the most our most distant points from the Sun in this century. Every year, the Earth reaches its aphelion, or farthest point in its elliptical orbit, in approximately the middle of northern hemisphere summer. However, the Earth and Moon also swing around a common barycenter, much like two pirouetting ballroom dancers.  This means that in addition to our usual distance at aphelion, about 3% greater than perihelion, the New Moon has also swung us out by an additional several thousand miles!

Has the “Pioneer Anomaly” been pinned down?: As reported here at Astroguyz a few months ago, a mysterious force has seemed to be playing with the Pioneer spacecraft, which made the Grand Tour of the outer planets in the 1970′s. This unknown force caused minuscule but discernable drift movements of both craft, Pioneer 10 and 11. This nagged at astrophysicists; could a tweaking of the law of gravity on very large scales be in order? Now, a scientist at Pasendena’s Jet Propulsion Laboratory may have found an answer. Going back through mountains of Pioneer mission data, Slava Turyshev has noted that thermal emissions were not previously modeled to a high degree of accuracy. Accounting for these explain the offset rather well. Even photons do impart a tiny bit of momentum, and this does add up. Incredibly, the Pioneer missions were of a long enough duration to outlast operating systems; when first launched in the early 70′s, punch cards were the high point of computer vogue!

GLAST Update: The GLAST, or Gamma-ray Large Area Space Telescope, was successfully launched from Cape Canaveral Air Force Station on June 11th at 12:05 PM, EDT. The gamma-ray observatory will replace the Compton Gamma-ray Observatory, which was de-orbited. Its mission is to study gamma ray bursts, some of the most energetic and distant bursts in the universe. GLAST also covers some high energy ends of the spectrum that other space telescopes are unable to scrutinize. Gamma-ray astronomy is an extremely new branch of space science; twenty years ago, it barely existed! This is due to the fact that gamma-rays are largely absorbed by our atmosphere; optimal sites for a gamma-ray observatory are either on high mountain tops or in space. Extra-galactic bursts were only observed when the US began monitoring Soviet nuclear tests from space. NASA states that after a 60-day check-out, the gamma-ray science will begin!

Bizarre Solar Flare: As readers know, the sun is still at a 11 year solar minimum. However, that doesn’t stop our nearest star from releasing the odd solar flare. On April, 27th of this year, the sun did just that; and it released the flare without the usual accompanying sunspot, to boot. The flare through off several earth masses worth of material into space, and registered  as a class “B” x-ray flare, small but noticeable. The scale, from smallest to largest, goes B, C, M, X. A pneumonic, anyone? SOHO and NASA’s STEREO spacecraft were also witness.

Full Moon of the Month: The July full Moon is known as the Buck or Thunder Moon by the Algonquin Indians. It occurs on  July 18th at 4 AM EDT.

Carter Roberts. A Loss to the Community: The world of amateur astronomy lost one of its own recently; Carter Roberts died April 24th of this year after a two year battle with colon cancer. President of the East Bay Astronomical society in San Francisco for the past two decades, he was a geophysicist by trade, but an astronomer at heart. He was renowned for his encyclopedia-like knowledge of astronomical information, often able to quote a reference direct from the source. He worked tirelessly to promote astronomy in the San Francisco bay area and the world. He will be sorely missed.

Quote of the Month: “Night is certainly more novel and less profane than day. I soon discovered that I was acquainted only with its complexion; and as for the moon, I had seen her only as it were through a crevice in a shutter, occasionally. Why not walk a little way in her light?”- Henry David Thoreau, Night & Moonlight.

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