November 1, 2014

Astro Event: A Very Close Dawn Conjunction.

 

Jupiter & Uranus at Appulse! (Created in Starry Night & Paint).

Jupiter & Uranus at Appulse! (Created in Starry Night & Paint).

 

 

    Tomorrow morning has something worth getting up for; one of the closest planetary conjunctions of the year. Specifically, the planets Jupiter and Uranus sit about 26’ arc minutes apart, as seen through binoculars. Both will also fit nicely in a low power telescopic field for the next week or so. Jupiter has been very much in the news as of late, as it first became suddenly “one striped” a few weeks ago and was recently smacked again by an impactor. When we first caught wind of this, our first instinct was hoax, such as the “Mars is the closest this August in 50,000 years!” email that circulates every summer. But it does indeed appear that another impactor has struck the giant world, on the same calendar date and discovered by the same observer! We’ve definitely received a lesson in Jupiters’ role as a cosmic vacuum cleaner as of late, although no true impact scar has yet to reveal itself. It’s also worth noting that the impact longitude will be on the planet’s central meridian at 4:21 EDT tomorrow the 8th as well, another reason to check out Jupiter. The impact video that circulated revealed the hit to be right at the longitude of the missing Southern Equatorial Belt. Uranus will be slightly fainter than a typical Galilean moon and display a grayish green disk. The pair rises around 3AM local and a waning crescent Moon will be nearby. Fun fact: did you know that Galileo missed the opportunity to discover another outer world, Neptune, during a close conjunction? He even drew its position change next to Jupiter in his notebook! Probably the reason that he didn’t make the intuitive leap was because no one at the time supposed that there should be any undiscovered planets!

The Astro-Word for this week is Appulse. This is another term that points back to astronomy’s hoary roots with astrology. We say an object (usually two planets or a planet and the Moon) are at appulse on their closest apparent approach. Of course, this is only line of sight from our vantage point; in reality, objects such as Jupiter and Uranus are millions of miles apart. The term appulse has sort of fallen to the wayside in favor of its synonym, conjunction, but it certainly doesn’t raise the eyebrows like another related mystical sounding term, occultation. I’m just glad that professional astronomers no longer have to subsidize their income by casting horoscopes for kings, as they did in times of yore!

Astro-Challenge: See the Galilean Moons in 1,2,3,4 Order.

The Jovian System at 3AM EDT Friday. (Created by Author in Starry Night & Paint).

The Jovian System at 3AM EDT Friday. (Created by Author in Starry Night & Paint).

 

   Astronomy is chock full of alignments, synchronizations, and oddities that happen on variable cycles. This week, I’d like to point you towards one of those gee-whiz occurrences that happens early Friday morning. On May 28th, 2010, you’ll have the opportunity to view Jupiter’s classical four Galilean Moons in one-through-four order, all positioned on one side of the planet. This would also make for an interesting “family portrait” of the set. Jupiter is in dawn skies, currently rising about 4 hours prior to the Sun. The window of time is short; the moons are only in this arrangement from 06:33 UT until 07:50 UT, and “Jupiter-rise” for folks in the US Eastern time zone only occurs at about 0:700 UT (about 3 AM EDT local). Hence, only folks positioned in the Eastern and Atlantic time zones will have a shot at catching this alignment under dark skies. [Read more...]

3.8.9: Jupiter Occults a Bright Star.

Jupiter w-star

Lots has been afoot in the Jovian system as of late. As you train that 10” Dobsonian on the ever evolving black spot gracing Jupiter’s cloud tops, I turn your attention to another unique event about to occur tonight; the occultation of a bright star by the large gas giant. The star is 45 Capricorni, which is currently crossing our line of sight with Jupiter. At about sixth magnitude, it will masquerade as a Galilean satellite over the coming days.The actual occultation begins at 23:00 Universal Time (UT) on August 3rd and lasts until 1:00 UT on the 4th. Europe, Africa, the Canadian Maritimes and extreme northern New England will be well placed to see this rare occultation; the remainder of the Americas will see 45 Cap rise with Jupiter at about 9 P.M. local. An occultation of a bright star by a planet is rare because planets are intrinsically small targets in terms of visual diameter, and stars that they can occult are constrained to those along the path of the ecliptic. Speaking of which, the four large moons of Jupiter are also currently under going a fascinating series of mutual eclipses as we transit their respective orbital planes; check out the link above for more info, and watch the occultation of 45 Cap if you get a chance. Some things to watch out for; does the star “wink in, wink out” in a step wise fashion, or fade gradually in and out? You could be seeing evidence of Jupiter’s atmosphere refracting the starlight; or perhaps this is glimpse 45 Cap’s binary companion! Also known as HIP 107302, this star is also listed as a close spectroscopic double. This will also be the brightest star that Jupiter has occulted since 1952. [Read more...]