August 21, 2017

03.05.11: The Mysteries of Vesta.

A projected model of Vesta. (Credit: NASA/JPL/CALTech/UCLA/PSI).

In a string of recent firsts, scientists are about to get a good look at an enigmatic solar system body for the first time this summer. Launched in 2007, NASA’s Dawn spacecraft is due to orbit the asteroid Vesta in August of this year, giving us the first non-blurry close up images of the 530 kilometer diameter world. [Read more...]

17.03.11- Mercury: At Last!

Brave New World: Mercury as seen from Messenger during 2nd flyby departure.

 (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington) 

Tonight marks a pivotal moment in solar system exploration. At 12:45 AM UTC on March 18th, NASA’s Mercury Messenger spacecraft will burn its engines for approximately 15 minutes to enter an elliptical orbit around the planet Mercury. Since its launch from Cape Canaveral on August 3rd, 2004, Messenger has flown by the Earth once and Venus twice for a gravitational assist, swung by the innermost world three times, sampled the near solar environment, searched for Vulcanoids, and even done a wide field pan for any tiny Mercury moonlets that may have been missed. [Read more...]

Tricks at the Eyepiece

Sure, you’ve got the gear, you’ve got the ultimate telescope, or maybe you just like to causally observe. But have you ever given much thought as to how to observe? The simple act of looking is so reflexive that most of us do it without a second thought. In the realm of astronomy, however, the use of a trained eye is paramount to enjoying what you’re seeing.

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AstroEvent: Can You Spy the Zodiacal Light?

This week’s astronomy challenge is seasonal for mid-latitude observers. Around the time of the equinox, the ecliptic meets the horizon at a favorable angle and a unique phenomenon may become apparent: the zodiacal light. This diffuse band of light can be briefly seen after sunset or before sunrise from a moderately dark location.

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05.02.11: Postcards from Saturn.

Rhea and friends…(Credit: Cassini/NASA/JPL).

Ahhhh, but to be a fly aboard a Saturn-circling mission… this weekend, I want to turn your attention to some fairly amazing imagery coming from NASA’s Cassini spacecraft in orbit about Saturn. Cassini has just completed a flyby of several moons, including Enceladus, returned some first ever images of the tiny moon Helene, and on January 11th, took the close-up of Rhea pictured above. [Read more...]

Near Earth Objects: Mitigating the Threat.

(Editor’s Note: What follows is a scenario/article along with an original lesson plan re-written for a blog format).

Arizona Meteor Crater… x100=a bad day for the Earth? (Photo by Author).

Eventually, it had to happen. With scant warning, the announcement is made that a large space rock is inbound to strike Earth and is only weeks away. The news largely takes the public by surprise; this is the big one, an extinction class event. People are exasperated to learn that little can be done to deflect the large impactor; all that remains is for scientists to predict the precise impact location and for world organizations to attempt evacuations so that some of humanity might survive… [Read more...]

04.01.11:A Martian Eclipse.

Phobos in transit. (Credit: NASA/Cornell/JPL/Texas A&M)

I never get tired of catching a glimpse of the sky from other vantage points in the solar system… today, as residents of the Old World enjoy a partial solar eclipse on Earth, we thought we would direct your gaze to an eclipse from Mars. [Read more...]

The Discovery of Eris & its Implications

Eris & Dysnomia as seen from Hubble. (Credit: NASA/HST/ESA M.Brown).

As 2010 draws to a close, a quiet discovery was made recently about a fascinating solar system object. January 5th, 2011 will mark the six year anniversary of the discovery of 2003 UB313, which became provisionally known as the planet Xena and then later demoted to the dwarf planet Eris. [Read more...]

Astro-Event: A Very Old Moon Pairs with Venus.

As viewed from North America the moring of Novenebr 5th. (Created by the author in Starry Night).

As viewed from North America the morning of November 5th. (Created by the author in Starry Night).

 

     This week’s astronomy challenge ties in two potential visual challenges: sighting a very slender crescent Moon and a daylight occultation of Venus. A grouping of the next two brightest objects in the sky after the Sun is always a treat; the challenge comes from the fact that the celestial pairing will be very close to a brightening dawn horizon. Venus just passed inferior conjunction on October 28th; it will sport a 2% illuminated crescent about 60” seconds in size at magnitude -4.2. The Moon, meanwhile, will be about 1% illuminated and reaches New on November 6th at 04:52 Universal Time. [Read more...]

24.04.10-Our Existence: Justified.

(Credit: NASA/JPL).

(Credit: NASA/JPL).

 Earth: Safe & Sound?

   The formation of the Earth poses a key dilemma to planetary accretionary theory; namely, why are we here at all? Standard models would say that the Earth and other planets coalesced out of the proto-solar nebula to form. However, spiral density waves within the same nebula should have drawn down orbital energy to shorten the planets orbit, slowly drawing it in. Looking at other “hot Jupiter” systems, that’s just what we see; large gas giant worlds that formed further out, only to migrate inward into tight orbits… just how did we end up in our nice, neat orbit?

Now, computational astrophysicist Mordecai-Mark Mac Loc at the American Museum of Natural History may have the answer. Accounting for temperature and spin variability, resonance key holes can occur; planets like Earth may simply spiral inward and get hung up in these safe zones between dragging pressure waves. Of course, a majority of proto-planets don’t make the cut and simply spiral inward to a fiery end, but they’re not around for us to see today. One discovery that would perhaps give observational weight to this theory would be the discovery of exo-Earths also parked in nice neat orbits… the Kepler space telescope may pave the way for this discovery as it stares off into Cygnus. For now, thank computational mathematics that you’re here reading this, just as it says you should be!

04.02.10: Pluto Re-imaged.

The brave new face of Pluto. (Credit: NASA, ESA, M. Buie).

The brave new face of Pluto. (Credit: NASA, ESA, M. Buie).

The most controversial planet (or do you say dwarf planet, or plutoid?) got a new look today. In a press conference, NASA researchers revealed the new “face” of Pluto; a series of images spanning 270 degrees of rotation. To complete these, astronomers scoured 384 images for 4 years using no less than 20 computers. These images were acquired from the Hubble Space Telescope’s Advanced Cameras for Surveys, and span a period from 2002-03. Even under the most favorable conditions, Pluto is a tough target; at around 0.1” arc seconds in size, Pluto only covers only a few pixels even in the best cameras and telescopes. The images are in true color, and present a tan-ish to grey world that is perhaps Mars-like in appearance. This is suggestive of a broad diversity of plutonian topography, and comparisons with the 1994 images show correlations with bright surface features, but also changes that hint at seasonal variations. Specifically, Pluto appears significantly redder and shows a magnitude variation of 0.2 magnitudes, which is surprising over a short 8 year span…Pluto takes 248 years to complete one orbit. Charon, Pluto’s large moon, was a good “color test” as it stayed the same throughout both imaging cycles, lending credence to the idea that the changes throughout were real and not an artifact.

Spectroscopic analysis reveals that Pluto is a dynamic world, covered by frozen methane and fluro-hydrocarbons. In fact, it’s suggested that the world may be a twin to Triton, Neptune’s largest moon. “Certainly, the Kuiper Belt is an amazing place,” such researcher Mike Brown, who laughed at the idea that perhaps Pluto was getting redder in anger at him due to its recent demotion. Hubble’s newly installed WFC3 camera will begin imaging Pluto over a five month period starting April 2010, in anticipation of the New Horizons flyby in 2015. And all this on today, Clyde Tombaugh’s 104th birthday! Expect those astronomy text books to be changing soon…

AstroEvent of the Week: October 27th- November 2nd; A Halloween Asteroid.

This Halloween brings a chance to spot one of the brightest known asteroids. 4 Vesta is currently placed in the constellation Cetus, the Whale and will be in opposition on October 29th this year, and thus be visible in moonless skies nearly all night.

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