December 18, 2017

Astro-Challenge: Spot a Near Earth Asteroid & More!

Some interesting events are afoot this last week of January into February for those who track the passage of “Low Flying Space Rocks” plus dirty snowballs across the northern hemisphere winter skies.

First up is a close pass of the Near Earth Asteroid 433 Eros. Fresh off of perihelion at a distance of 1.133 A.U. (Astronomical Units) on January 17th, this 21-mile wide (on its longest axis) asteroid passes 0.18 A.U. or 70 times the Earth-Moon distance on January 31st. The 2nd largest Earth-crosser after 1036 Ganymed, 433 Eros is also an Amor class or Mars-crossing asteroid and was the first Near Earth Asteroid to be discovered in 1898 by Carl Gustav Witt. At its closest, 433 Eros will move an apparent 3’ arc minutes per hour (a little over a degree a day) across the sky, enough to notice a nightly change against the starry background. Also, its worth noting that the “Erotian day” is about 5 hours and 16 minutes, over the course of which the oblong asteroids’ apparent brightness can vary as it tumbles end-over-end by a factor of four! 433 Eros will shine in the 8th magnitude range as it crosses from Sextans in late January into the constellation Hydra and falls below 9th magnitude in late February as it glides further south. It also has an interesting pass (within 2 degrees) near +5 magnitude Beta Sextantis on the night of January 26th-27th. The asteroid was visited twice by the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft, once during a flyby in 1998 and for a year-long orbit starting in 2001. Fans of Orson Scott Card may also remember 433 Eros as the setting for the Command School in his novel Ender’s Game.

The path of 433 Eros through February 2012. (Created by the author in Starry Night).

Do make an attempt to spot 433 Eros this year, as the last close passage was in 1975 & the next good passage isn’t until 2056! A good project would be to photograph it against targeted star fields on successive nights, or perhaps just sketch the area at moderate power and watch for the moving “star” from night to night. Sky & Telescope has an excellent article on finding Eros, and Heavens-Above is another great place to check for its current position.

In other asteroid news, 1746 Brouwer occults a +7th magnitude star on the morning of January 30th at 01:18 UT (8:18PM EST on the 29th) for observers along a path from SE Canada and the Great Lakes region to southern New England. Observers may see the star “wink” out for up to 4 seconds in duration. The target star HIP 12184 will also be easily identifiable as it’s a wide (38”) double, handy for visual acquisition.

A fine photo op will also present itself as Comet C/2009 P1 Garradd passes within ½° degree of the fine globular cluster M92 in the constellation Hercules on February 2nd-3rd. Comet Garradd has been a solid 7th-8th magnitude performer throughout the Fall of 2011 and should be an easy binocular object high in the morning sky throughout February. It reaches its nearest to Earth on March 5th at a distance of 1.27 AU, and stands only 19 degrees from the northern celestial pole on March 11th, making it a circumpolar target for much of the northern hemisphere starting next month.

Finally, February 2012 is not only a leap year, but it is also a month that’s “missing a Moon phase” as reckoned in Universal Time… that is, the First Quarter Moon occurs just an hour and 21 minutes into March 1st. February is the only month that can be missing one of the traditional four phases (New, 1st Quarter, Full, & Last Quarter) because it’s the only month shorter than our friend, the synodic period which is the span of time that it takes for the Moon to return to the same phase (i.e. New to New, Full to Full, etc). An average synodic period is 29 days, 12 hours, and 44 minutes 2.9 seconds long, although perturbations can make the actual period range between 29.18 and 29.93 days. For this unique quirk of our calendar to occur, any of the aforementioned  phases needs to  first fall on January 30 or 31st; as you can see, the window for this to happen is narrower still on a leap year, when February has 29 days!

Just how rare is this occurrence? Well, the last February missing a Moon phase was in 1999, and the last Leap year missing one was 1940… the next year containing a February missing a Moon phase is 2014, and the next leap year won’t be until 2052 A.D.!

Astro-Challenge: The Ruddy Hues of UU Aurigae.

Carbon stars are some of our “surprise faves” to show off to folks when it comes to variable stars. Objects like V Hydrae and R Leporis, otherwise known as Hind’s Crimson Star exhibit a cherry red hue as they fatten up on carbon fusion and filter through red-wavelength light late in their stellar careers. This week, I’d like to challenge you to point your scope high in the January evening sky at another colorful wintertime sight to add to your repertoire, UU Aurigae, a variable star located along the Gemini/Aurigae border. This star varies from a maximum brightness of +5 to a minimum of +7 to +10 with two superimposed periods of 233 and 438 days. UU Aurigae just came off of a minimum magnitude around +7 in the early Fall of 2011 and should be headed towards a maximum of +5 in spring of this year.

Created by Author in Starry Night, north is to the left.

A C5II-type star on the Morgan-Keenan C System of carbon abundance, UU Aurigae has an R-I color index of +1.43 (Hind’s, one of the reddest stars in the sky has a R-I of +1.47 for context) and is classified as a semi-regular variable. Observers report its color as a deep orange-to-red, and it’s always an interesting study to note how the color of such stars changes as they approach maximum. UU Aurigae lies 5 degrees NW of the +3.6 magnitude close double star (at 2.9” arc seconds of separation) Theta Geminorum. Its coordinates are:

Right Ascension: 06 Hours, 36.5’

Declination: +38° 27’

Good luck, and let us know about your respective observing anecdotes as you track down this ruby-tinged wonder.

In other astronomical events of note this week, the +14.8 magnitude asteroid 911 Agamemnon occults a +7.8 magnitude star in the constellation of the Lynx. The 200 kilometer-wide path will cover a stretch of the Earth’s surface touching down along the U.S. east coast across New Jersey-Virginia at 11:31 UT on January 19th, tracking across central Canada and Alaska before departing our planet over Siberia and Mongolia at 11:41 UT.  If you’ve never caught an asteroid occultation of a star, this would be a fine one to watch, and one of the better events of 2012.

Also Comet P/2006 T1 Levy reached a perihelion of 1.007 astronomical units from the Sun on January 14th and was predicted to have attained magnitude +7 by now as it crossed from Pisces into Cetus on the 17th; however, current observations place it more along the lines of less than +17 magnitude visually. It is suspected that the comet was in outburst when first discovered by David Levy from Jarnac observatory in Vail, Arizona (only miles away from the now defunct Very Small Observatory of Astroguyz fame.) The comet has apparently pulled an “Elenin” and disintegrated… hopefully, dependable Comet C/2009 P1 Garradd continues its track record as a fine binocular comet in the morning skies this spring.  Also sometimes listed by its recovery designation of P/2011 Y1 Levy, it’s still amusing to watch as certain unnamed and obviously automated sites continue to list P/2006 T1 Levy as a bright comet! Need a human astro-fact checker there, guys? Comet P/2006 T1 Levy will also make its closest approach to Earth on January 26th at just shy of 22 million miles (about 88x the Moon’s orbital radius) distant.

Finally, we’ve been following the stranded Russian Phobos-Grunt spacecraft on every pass over Astroguyz HQ this past week; the most recent updated projections for re-entry stands at 14:35 UTC on January 15th, ±1 day. This all assumes, of course, that the probe hasn’t already re-entered as you’re reading this! Interestingly, we have a visual pass over a local Star Party that we’re attending Saturday night January 15th! Come on out to Starkey Park if you’re in the New Port Richey area; you just might see UU Aurigae and a satellite re-entry to boot! Incidentally, rough back-of-the-envelope calculations for seeing Phobos-Grunt re-entering while above your local horizon (assuming you live between latitudes 50° north or south, along with about 95% of the human population) are about 300-to-1 against; a long shot, but better than the lottery! Also, the Phobos-Grunt saga has spun off a whole host of bizarre (and of course, web circulating) tales, proof of the Mark Twain  adage that a lie can fly around the world while the truth is “just putting on its shoes…” Not the least of which are that the probe will “hit Afghanistan” (the aforementioned odds for such a prediction aren’t much better for them than any other country) and that the HAARP array in Alaska had something to do with disabling the probe. (The failure occurred before the passage of the spacecraft over HAARP) still, we’re going to miss explaining the name “Phobos-Grunt” to friends and family, many who are already convinced that us astro-bloggers are a bit “off our rockers,” anyway!

Astro-Event: Aphelion, an Occultation, a Launch and a Close Double.

Sunday night’s occultation path across the US…(Credit: NASA/IOTA).

We bring you this week’s edition of astronomy events a tad early to point your eyes skyward towards an interesting event; the occultation of a 10th magnitude star constellation Virgo. The asteroid is 52 Europa, and the event will last for up to 18 seconds for viewers from Montana across the central US down to our very own neck of the woods in Central Florida. [Read more...]

AstroEvent: A Solstice, an Occultation and More!

Summer Noctilucents over Astroguyz HQ… (Photo by Author).

Astronomy lovers of the northern hemisphere take heart; the summer solstice occurs this Tuesday June 21st at 1:16 PM EDT/5:16 PM UT as the Sun reaches its most northerly point in its journey as viewed from Earth.  Of course, this motion is apparent (at least, to all but geo-centrists and flat-Earthers!) as our northern rotational pole is now tipped towards the Sun. [Read more...]

AstroEvent: 4x Planets, 1xMoon, and a 12° FOV!

Looking eastward May 1st about 30 minutes before sunrise. (Created by the Author using Starry Night).

Where have all the planets gone? Four of the five classical naked eye planets are about to reveal themselves this week in a splendid fashion. As Venus sinks morning by morning towards the horizon, expect Jupiter, Mars and Mercury to emerge low in the dawn sky. The action culminates the weekend of April 30th-May 1st, when the waning crescent Moon approaches the grouping… use brilliant Venus as a visual “anchor” to guide your eyes to the fainter planets. On what date will you be able to spot each planet from your location? [Read more...]