Stellar Occultation of P20120614 by Pluto

Stefan Réner, Ahmed Daassou and Zouhair Benkhaldoun took this image of Pluto and the target star, using the T60cm from Atlas Golf Marrakesh on the night 12 to 13 June. Credit

Although the suddenness of such an event is rather peculiar (as such an event should have been in ephemerides without such short notice), Pluto perhaps will occult the a star, P20120614 of the 13.7 magnitude during the night of June 13-14. In an alert entitled "Possible Pluto occultation Wednesday night (2012/06/14 03:28 UT) from US East coast" issued by Leslie Young, we find that Pluto's occultation hopefully will conclude to be helpful for more insight to Pluto, as it is a world of which we do not have much information from. The occultation is planned to last around sixty-eight seconds starting on June 14 at 3:22 UT (June 13 11:22 pm EDT) at a low altitude in the sky for the eastern United States and Canada. The RA (Right Ascension) of the star is 18h 35m 48.69s while declination is at –19° 17' '43.6".

From the alert, we learn that stellar occultations prove to help us learn more about Pluto, but particularly its atmosphere. "Pluto's thin, nitrogen atmosphere is in vapor-pressure equilibrium with the surface ice, and changes seasonally", so observable occultations will help astronomers learn more about the atmosphere. When Pluto passes in front of a star, we get a good view of the atmosphere by the light from the star behind the planet and meanwhile, at ~10 km resolution, temperature and pressure is measured accordingly. More information can be obtained here.

Visibility Map: Across the globe pictured above, the three solid lines correspond to the northern limit, centerline, and southern limit of Pluto's shadow. The northern and southern limits correspond to a radius of 1400 km. The upper and lower dashed lines indicate 3-sigma errors. The shaded area represents where the sun is more than 12 degrees below the horizon.

Table 1: Prediction Details
Pluto Geocentric Mid-time (yyyy month dd hh:mm:ss)	2012 June 14 03:26:12± 00:00:42 UT
Pluto Minimum Geocentric Separation	0.275± 0.025 arcsec
Position Angle (Pluto relative to the star; measured north through east)	–6.40 degrees
Geocentric Velocity	22.89 km/sec
Occultation Star R magnitude	13.8

Table 2: Reference Star Position
Reference star position: (at epoch of event)	RA (h:m:s; J2000)	Dec (d:m:s; J2000)		Notes
P20120614 Catalog	18 35 48.6931	–19 17 43.617
P20120614 Measured	18 35 48.6883 ± 0.002	–19 17 43.639 ± 0.009		From 5 SMARTS Telescope frames.
Table 3: Projected KBO Offsets from Reference Ephemeris at the Time of the Event
Body	RA (arcsec)		Dec (arcsec)
Pluto	–0.1392± 0.041		+0.225± 0.023

Above Tables and Visibility Map Thanks to P20120614 Occultation June 14, 2012. Below map credit same site the image of Pluto and Star (beneath the title) was accessed.

Dark gray is night and light gray is astronomical twilight (Sun at less than 18° below the horizon).
Shadow moves from right to left, each red dot is separated by one minute, the nominal occultation time on the map, is for the big red dot, the closest approach

The June 5, 2012 Transit of Venus: Never Again Until 2117

Fred Espenak's composite image of the Transit of Venus 2004

After waiting since 2004 for another Transit of Venus, the 2012 Transit of Venus has finally arrived, preparing millions of viewers worldwide to see the spectacular event. Loosely described as the quiet silhouette passing across the luminous disk of the sun, the rare astronomical phenomena of the Transit has stunned and amazed astronomers throughout the ages and now another is upon us. You, who are reading this article now, will never be able to witness another Venus transit again in your lifetime: as the next comes in 2117. 

As we already know that Venus transits are rare, coming in couplets distributed over hundred year periods, what exactly is a transit, defined in an astronomical sense? Though eloquent as it may sound, planetary transits are far less common then eclipses, as the planets align much less frequently then the moon does. The Oxford Dictionary of Astronomy states that a transit is "the passage of one object across another of larger apparent diameter, such as Mercury and Venus in front of the Sun, or its shadow across the face of a planet." Correctively speaking, when a shadow crosses a larger object, it is hence called a shadow transit. So, there are two types of transits: shadow transits and regular transits (with no special name except for ‘transit’). Transits of planets across the Sun will not have a shadow cast, but usually transiting moons do. 

Io usually casts a shadow when transiting Jupiter’s surface (the Sun’s light help Io cast shadows), while Mercury won’t because it transit’s across the Sun’s disk—nothing is there to cast a shadow. That brings me to an important observation: only two planets may transit the Sun as viewed from earth. They are Mercury and Venus. Because earth is the third planet in planet progression in the solar system, we can only see two planets transit, whereas Saturn can see five; Mercury, Venus, earth, Mars, and Jupiter. Jupiter is probably big enough to blot out the Sun as viewed from Saturn, so it could be considered a planet eclipse. These are rare occurrences; and not much interest has been given to it. 

Yet, the history of such a rare astronomical phenomena is quite spectacular. Unlike eclipses that have been viewed from so early on in the books of the past, about one-thousand BC, the first transit (of any celestial body) was viewed on November 7, 1631 by French astronomer Pierre Gassendi. It was a transit of Mercury across the Sun’s disk; predicted by Johannes Kepler just four years before. Mercury also transited in years that followed; on November 7,1677 Sir Edmund Halley (who discovered Halley’s Comet) was the first man ever to witness a complete transit of Mercury, Gassendi obviously did not catch a whole transit, but a partial one. All that you really see is a black spot moving across the Sun’s surface. Mercury takes up 1/194 of the Sun’s disk, so although it may seem like nothing, it is an extremely rare astronomical event. 

Venus, because of having a larger orbit, transit much less frequently, making it an extremely rare event. Only seven events have ever been viewed since the making of the telescope (as of 2010). Just one month after Gassendi viewed the transit of Mercury, Venus transited, but when Gassendi tried to view it, he tried in vain, because the transit was not able to be seen in Europe. Later on, astronomers Jeremiah Horrocks and William Crabtree became the first two men ever to witness a transit of Venus, but there has been some controversy to that. On May 24, 1032 AD, Persian polymath Avicenna had claimed to be the first man ever to observe a transit of Venus. He wrote Compendium of the Almagest (a commentary on Ptolemy’s Almagest) in which he concluded that Venus is closer to Earth than the Sun. This was a great step in astronomy at the time, because geocentric views of the universe were taking shape. If the universe was geocentric, that meant the earth was the center of the universe. The heliocentric view (Sun is the center of the universe) was not used at all.

As mentioned before, only two planets may ever transit the Sun as viewed from earth. Mercury appears as a small speck on the Sun’s surface, while Venus is a bit larger. Edmund Halley, also used transits as a great help: “Edmund Halley first realized [in 1716] that transits could be used to measure the Sun's distance, thereby establishing the absolute scale of the solar system from Kepler's third law. Unfortunately, his method is somewhat impractical since contact timings of the required accuracy are difficult to make. Nevertheless, the 1761 and 1769 expeditions to observe the transits of Venus gave astronomers their first good value for the Sun's distance” stated the Transits Page at NASA’s eclipse website. This helped us determine how far the Sun is away from us, and gave Halley the credit for his observation. 

In 1631, 1639, 1761, 1769, 1876, 1882, and 2004 Venus was seen transiting. It is much rarer (Mercury transits so much more) because Venus’ orbit is much larger than Mercury’s. The larger the orbit of a planet is; the less likely an astronomical transit is to take place. Only in early June and December can you view one; if there is an eclipse in early June as well, then two spectacular events will occur in one week! On June 5/6 2012 (depending where you live on the globe) Venus will transit the Sun for the last time until 2117. On June 4^th (2012), a partial lunar eclipse will occur, so this week will be a treat for all who live around the Pacific Ocean. It turns out the complete visibility for the transit of Venus one/two days later is also the Pacific! (These may also be viewed In North America—but at sunset).

Transits of Venus are special—not only because they are so rare, but because they come in pairs of eight years. That explains why Venus transited in 2004 and will again in 2012. This is because the orbital periods of Venus (224.701 days) and earth are in an eight year (2922 days) resonance within each other. It takes eight years for earth to orbit around the Sun, and Venus thirteen, for both the orbits to exactly line up with each other. The first two times earth and Venus meet with each other, a transit is produced, but, Venus arrives twenty-two hours earlier the third meet, resulting in earth missing Venus completely. That’s why transits are so rare. The next one takes 105.5 or 121.5 years to make another transit. Two Mercury transits, on the other hand, are consecutive between 3.5, 7, 9.5, 10 or 13 years. This pattern is very complex on account of Mercury’s elliptical orbit. From there, a plethora of different year combinations come up, each resulting in a different calculation of years. By adding the years between transits, for example, one used commonly is 10 + 10 + 13 which equals 33, produces a better fit than just 10 or 33. Hundreds of combinations like these can be combined, giving us an irregular pattern of transits. 

Another boggling concept is transit ‘Saros.’ Just like the eclipse Saros, transits can be grouped into families. The Venus transits of the years 1518, 1761, and 2004 would belong to one family, while transits in 1639, 1882, and 2125 would belong to another. Those groups were determined by a period of 88,756 days (or 243 years) in which this transit ‘Saros’ is grouped. Mercury’s transits can also be grouped, as in one set (separated by 16,802 days or 46 years) separate the years 1957, 2003, and 2049 belong to one group, and 1960, 2006, and 2052 belong to another. Although a little too complex to explain in a short paper, transit ‘Saros’ is a very original idea; for almost all astronomical phenomena can be grouped in some way or another!

It is plain to see the history of transits is spectacular. But, will I be able to see the transit of Venus on June 5-6? The answer is yes and no. Yes: everyone on every continent at various times will be able to see the event. No: you need a special filter (to block out dangerous rays from the sun) and a telescope to see the actual planet. DO NOT LOOK DIRECTLY AT THE SUN, as its rays will blind you—many astronomy companies sell special filters for such events. 

Visibility map from eclipse-maps.com

For more on this amazing celestial events, Sky&Telescope has a plethora of information about viewing times and what you'll see with a telescope (and special filter!). 

SLOOH Space Telescope featuring Transit of Venus

See more images of the 2004 Transit of Venus Gallery thanks to Spaceweather.com

The Annular Eclipse of May 20 2012

Being the second major solar eclipse event of 2012, the annular eclipse of May 20, 2012 is sure to bring about some impressive photographs as the moon passes in front of the sun. Unlike typical solar eclipses, annulars constitute a niche in astronomical classification for eclipse not only because of their rarity, but mostly because of their peculiarity. An eclipse, loosely defined, occurs when the moon passes in front of the sun, leaving a certain place on earth with no or some part of the sun, as seen by inhabitants of a region. The moon literally blocks out part of the sun for observers. However, depending whether the moon is at apogee and perigee can help define whether such an event will be annular or not. As defined in Matthew Winter's Astronomical Events: Eclipses, Transits, Occultations and Conjunctions, we get a good picture on the elements of an annular eclipse.

It [an annular solar eclipse] is defined as ‘a solar eclipse in which the Moon's antumbral shadow traverses Earth (the Moon is too far from Earth to completely cover the Sun). During the maximum phase of an annular eclipse, the Sun appears as a blindingly bright ring surrounding the Moon,’ from NASA’s Glossary of Solar Eclipse Terms. Annular eclipses are straightforward as well; the moon is fully inside the Sun’s disk, but does not cover it. This is because the moon is at perigee. The closer the earth to the moon, the more frequent the annular eclipse. The sun appears as a great ring, because the moon’s orbit is not completely circular, rather it’s an ellipse that travels in an oval. Unfortunately, the Sun’s corona is lost, but a few phenomena occur; annular eclipses only produce shadow bands, but are usually hard to see, even if any occur. It cannot produce Baily’s beads or the diamond-ring affect, because those can only happen under complete totality. So, on occasions, shadow bands will come into view, but don’t count on it. They’re blurry and difficult to relate to if you see any.

In short, annular eclipses have only one important criterion that must be met in order to form such an event: the moon must be at perigee, or farthest from the sun; only then can the sun be seen as a complete ring, which was named accordingly. (Annulus is the Latin word for "ring"). 

Visibility for the May 20, 2012 eclipse

Statistics for this eclipse, the visibility and frequency of others of its kind, are great. Visibility entails where the event will be able to be seen: from Eastern China across the Pacific Ocean to the Southwestern States are among the multitude of places that spectators will be able to witness the eclipse. "In the United States, the eclipse begins at 5:30 pm PDT and lasts for two hours. Around 6:30 pm PDT, the afternoon sun will become a luminous ring in places such as Medford, Oregon; Chico, California; Reno, Nevada; St. George, Utah; Albuquerque, New Mexico, and Lubbock, Texas. Outside the narrow center line, the eclipse will be partial. Observers almost everywhere west of the Mississippi will see a crescent-shaped sun as the Moon passes by off-center," Spaceweather.com comments. The point of greatest visibility will take place just south of the Aleutian Islands in the North Pacific for five minutes and forty-six seconds. This will be the place where the ring, or annulus, will be seen the greatest.

Taking part in Saros Cycle 128, the annular eclipse of May 20 2012 repeats every eighteen years and eleven days, altogether containing 73 events. "Solar eclipses of Saros 128 all occur at the Moon’s descending node and the Moon moves northward with each eclipse. The series began with a partial eclipse in the southern hemisphere on 0984 Aug 29. The series will end with a partial eclipse in the northern hemisphere on 2282 Nov 01. The total duration of Saros series 128 is 1298.17 years," NASA's eclipse website propagates. For more about Saros 128, NASA's eclipse website's database is superb. More information about Saros can be found there as well. 

When viewing this annular eclipse, like any other solar eclipse, it is important that one realizes the safety precautions that need to be made known. Do NOT attempt to look at the sun without the appropriate filter (or even sunglasses), because of the high risk for blindness. Many astronomical websites have stores where you can buy the appropriate equipment for viewing the sun.

Get your own valid XHTML YouTube embed code

Recommended links for further information

NASA’s eclipse web site http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html

Detailed weather reports for this eclipse at Jay Anderson’s web site, http://eclipser.ca/

Descriptions and interactive maps by Bill Kramer at http://www.eclipse-chasers.com/tseNext.php?TSE=ase2012d

Interactive Google map by Xavier Jubier at  http://xjubier.free.fr/en/site_pages/solar_eclipses/ASE_20120520_pg01.html.

National Astronomical Observatory of Japan: http://naojcamp.mtk.nao.ac.jp/phenomena/20120521/summary-en.html

U.S. Naval Observatory and HM Nautical Almanac Office: http://astro.ukho.gov.uk/eclipse/0132012/

May 14's Esoteric Crescent Venus

An exclusive of Spaceweather.com, this image of crescent Venus poses the fact that Venus is transforming into a slender crescent, as viewed from earth. Prepared to transit for us June 5-6, 2012, Venus is the brightest object in the night sky (except for the moon, of course) but will, over the summer, sink down into the golden beams of the sunset, and will officially become a morning planet in the autumn. But, this photograph has something perhaps "esoteric" and mystical about it. John Chumack of Dayton, Ohio, took the picture on May 14th using a 10-inch telescope. "I was blown away by the sight of Venus," he says. "The planet was 14% illuminated, 47 arcseconds in diameter, and blazing at -4.43 magnitude."

Detail of above picture

Kevin R. Whitman experienced Venus in a different manner. "Venus is as striking through a telescope as it with the naked eye. Its thin crescent phase along with Earth's atmospheric refraction of its ample light makes for a beautiful image through my 10-inch telescope. Image obtained with a Meade 10-inch LX50, f/20 using an Imaging Source DFK web camera. Processed using Registax 5." With the help of the atmosphere, Venus' light was able to refract and divide into the spectrum for this exciting image of the planet.

Detail of above picture

 As for now, Venus transeat!

Stellar Occultations for April 25-26

For two days this April, two different 3-4 magnitude stars will occult for Western Africa both times, with a plethora of other locations on each separate dates. With the moon waxing after being full April 21, the stars should not be too difficult to see and should provide a wonderful show for spectators.

APRIL 25, 2012: OCCULTATION OF ζ TAURUS

 

The moon will only be 17% illuminated when this occultation of Zeta Taurus occurs, giving Western Europe and Africa a wonderful seat. France, Spain, Italy, Germany, (part of) England, and most of the north-western coast of Africa are just a few of the many locations (you can find ephemerides here) the occultation will be visible. Zeta Taurus is a binary star of the 3.010 magnitude on the far right side of the zodiacal constellation of Taurus, situated approximately 440 light-years from earth; although without highly-technological equipment the two stars that comprise Zeta Taurus will cannot be discerned, it is bright enough to be seen with the naked eye, but binoculars or a telescope will make the event more expressive. 

APRIL 26, 2012: OCCULTATION OF γ GEMINI

Although the visibility of the occultation is practically the same as the occultation yesterday (April 25, above), most of north-western Europe will not be able to see Gamma Gemini be occulted by the moon. With a moon illumination of 25 percent, it is the prime time for this rather-dim star to occult: it being at 4.1, according to IOTA stellar occultations, ephemerides for locations of this occultation here. Western Africa will be the prime location for this event, as most of Africa's north-western part is in the visibility zone.

The Moon Returns to Jupiter and Venus

A perfect month ago from March 25, 2012, Venus and the young moon paired up with each other for a spectacular evening of the brightest planet and moon; astrophotographers and sky viewers experienced a beautiful skyscape amid the colors of the setting sun. But with that having been said, it is only fitting to speculate that what more could they do? For, as any stargazer knows, the moon will repeat its positions in the night sky after every revolution, and Jupiter and Venus will still be there; they're going to do it all over again!

 
This Sunday, March 25, 2012, Venus and Jupiter will be seen in the early evening to perhaps "conjunct" or pass close by the moon again, to provide us with another picturesque scene of the planets. On this date, Jupiter will be a quite number of degrees to the south of Venus (after their conjunction mid-March) and the moon will be (on the 25) next to Jupiter. Although Jupiter and Venus are continuing to travel on into the sunset (as they will be lost there in early May 2012), on March 26, the Moon will crest Venus; it traveling thirteen degrees each day, which explains the Moon's "retrograding" position in the night sky each day.

Viewing Venus will be a special treat this upcoming week, Sky and Telescope explains: "This is also a great time to view Venus through a telescope. You're actually more likely to see fine details in Venus's clouds during the day than at night, when Venus's overwhelming brilliance tends to overwhelm your eyes." It will transit the sun this June. What's that? Visit our page.

The Procession of the Planets: What Jupiter and Venus Did March 12-15

The conjunction of Jupiter and Venus amazed many the past few nights with their display during conjunction. Only about three degrees from each other, Jupiter and Venus aligned and created a beautiful, picturesque scene for many astrophotographers and views around the globe. Below is a collection of the many photographs taken of this marvelous event!

The images are (according to captions) 1) Aleksander Gospic from Zadar, Croatia. "Conjunction of Jupiter and Venus in the western twilight sky behind Zadar's Greeting to the Sun installation and its Sun, which never sets ..." 2) Geoff Chester from Alexandria, Virginia (Note: This image is amazing, not like all of them aren't!). "As I was biking home tonight I stopped to look at the two planets on the Route 1 bridge over Four Mile Run. The water was particularly still, and despite the high-tension transmission lines it seemed worthy of an image. So here are two images stitched together. If you look carefully in the lower half of the composite you can see the reflection of Venus in the water." 3) Marco Meniero from Pisa, Italy. 

These are my favorite selections, there are more to be found on Spaceweather.com! 

1

2 (SEE THIS IMAGE IN FULL DETAIL HERE)

3

The Cryptic World of the Satellites of Distant Pluto

Designated 134340 Pluto, this second-largest dwarf planet in the solar system is one with a history of no other planet, such as its downgrade and climatic discovery in the mid twentieth century; but one of the most remarkable aspects of this cryptic world are its specialized brood of moons which it harbors so well astronomers have never been able to photograph them, or even Pluto itself (in high resolution) to say the least! So what makes this distant, icy world so fascinating it's rather arcane? The answer to that question lies in your perspective of the planet: probably because we know nothing about it, or because of its hidden mystery and history of its creation (etc). Pluto is a rather special dwarf-planet; it lies within the Kuiper Belt, a belt of objects beyond the orbit of Neptune and orbit the sun in irregular orbits, along with many other know minor and dwarf planets such as Eris (the most massive dwarf planet in the solar system), Makemake, and Haumea to name a few.

The green objects represent the wide variety of objects in the Kuiper Belt, Pluto including. This map shows the area of the Kuiper Belt and the comparison of its distance from the gas giants (such as Jupiter) in the center.

Although not the only minor planet to have a collection of moons, Pluto has the most known of all dwarf planets. With a count from March 2012, Pluto has four moons, three of which have been named officially by the International Astronomical Union (IAU). Its most famous would be Charon, which was discovered June 22, 1978 (publicly announced July 7) by James Christy at the United States Naval Observatory Flagstaff Station while he was carefully observing photographic plates of the minor planet. A bulge was noticed periodically while plates were being taken and it was obvious this bulge was not a result of an error on the plate, but rather a moon orbiting the planet. Although this was rather controversial for a while, any doubt of no lunar presence was annulled during the eclipse period of Charon during the 1980s (specifically 1985-90).

"It was fortuitous that one of these intervals happened to occur so soon after Charon's discovery," Swarthmore College Computer Society writes in their article of Charon, and it was beneficial! The eclipses of Pluto are an extremely rare phenomena which can occur only twice per the planet's 248 year revolution around the sun, the next ones to occur start October 2103, peak in 2110, and will end January 2117, as observed from earth. It will be Charon who does most of the eclipsing for Pluto. More can be read here about the phenomena.

The Sun disappears behind Charon's surface during the total solar eclipse on Pluto of 23rd December 2111 (computer simulation) Thanks to Wikipedia and JPL simulator

The complete Plutonian system (as of 2005) thanks to the Hubble

Charon is not the only moon Pluto has, however! Three others have been discovered since the days of Charon's discovery and people are becoming less and less more skeptical about the existence of such objects. Nix (also spelled Nyx) and Hydra are two others discovered in July of 2005 by the HST Pluto Companion Search Team. The discoveries of both were publicly announced on October 31, 2005 after more than five works of research and confirmation from precoveries done in 2002.

Nyx, named after the Greek goddess of the night (all moons of Pluto were named in accordance to deities of the Underworld, as Pluto was the god of the Underworld in Greek mythology; Charon was named after the ferryman who took souls into Hades across the river Styx), orbits in the same plane Charon does and orbits every 24.9 days with a unique 1:4 orbital resonance with Charon (although not quite). The Nictian surface is quite unknown (like Pluto's) and is usually at the measured magnitudes of 23.38 to 23.7, almost 6300 times dimmer than the dwarf planet itself! But, its orbital resonance was a problem (because it was not perfect). In a paper presented by the discoverers of the moons entitled Orbits and Photometry of Pluto's Satellites: Charon, S/2005 P1, and S/2005 P2. This paper explained that although the orbital resonance between these objects were mostly 1:4, there was a 2.7% timing discrepancy, proving no resonance existed. The below portion of text discusses this on a higher level. 

The orbital period of P1 is 38.2065 ± 0.0014 days, while 6 times the period of Charon is 38.3234 days. This is the period ratio most nearly commensurate, and from the 0.3% difference from a 6 : 1 period ratio we get a circulation of the resonant argument in 2090 ± 80 days, less than 6 yr. Likewise, our period of P2 is 24.8562 ± 0.0013 days, compared with 4 times the period of Charon, which is 25.5489 days. This difference corresponds to a 2.7% difference, and thus, the resonant argument will circulate in only 229 ± 2 days. Comparing the periods of P1 and P2, we find that their ratio is 1.53710 ± 0.00006, not the exact ratio of 3/2. Again, circulation would be quite rapid, at just 515 ± 6 days. These circulation periods are all of comparable timescales to the duration of the constraining astrometry for the two-body orbits we have derived. We do not see any obvious periodic deviations from a two-body Keplerian orbit and thus argue that perhaps there are no active resonances.

Hydra (named after the chthonic beast of nine heads in the Grecian underworld) was discovered with Nyx and remains virtually unknown as the others. Its magnitude is just a tad brighter than Nyxs' at 22.9 to 23.3, and its orbital resonance with Charon made an issue as well as Nyx's. The Hydrian revolution was 1:6 to the Charonian one and (not suprisingly!) there was a 03.% timing discrepancy between the two, making no resonance at last.  

With that having been said, Pluto's three moons discovered 2005 and before have become a pivotal part of the history of Pluto, the planet we know almost nothing about. But then, in July of 2011, another moon was discovered. This moon was not the farthest moon out, as most moons are discovered in their order from closest to out-most of the planet [probably because the closest moons are the largest and most prominent and the outer are less-brighter and more hard to detect], but rather it was found to orbit between Hydra and Nyx. This moon, labeled S/2011 P1 was discovered (announced) on July 20, 2011, and is relatively dimmer than the other moons, at magnitude 26.1 ± 0.3. The plus/minus symbols details that the magnitude has been seen to shift as it orbits the planet. You can read more about Pluto's fourth in our article we published back in July when it was discovered. [Below is an image of P4 orbiting the planet]. 

When we image what Pluto may look like, we imagine a gelid, ice-ridden world void of life and any consolation. But amid the depression that lurks throughout the planet, we will always have the exciting anticipation of one thing: New Horizons. This discussion of Pluto's moons would never be complete without NASA's excellent space-probe sent out to explore than planet and its moons, hoping to discover new ones. It won't reach the planet until (proposed) July of 2015, so although the wait is burdensome, the rewards will be plenty! Pluto is not an icy world but a world of discovery, something we can all take part in.

Jupiter and Venus Conjunction 2012

The night of March 13/14 will be the night of the closest conjunction of the two-brightest night-sky planets, Jupiter and Venus. Both shining at around -4 and -2 degrees magnitude, Jupiter and Venus are and will be a spectacle of the night sky over the next few days not only for their beauty, but also for their "science" behind them, the conjunction, that is.

Astronomers call this event a conjunction, or the close passing of two astronomical objects as seen from a vantage point on earth; if you live on one side of the globe, though, the event will most probably look different than on the other side. For example, people in Asia might see the planets conjunct at a different angle and us here in America. Jupiter and Venus, as seen from the United States, will conjunct only three degrees apart from each other, and it is possible that both can be blotted out with an outstretched arm. MSN notes, though, that as time passes on, the degrees of the two planets varies, "Wednesday night, for example, they'll be separated by just 3.1 degrees. By Thursday, the gap between them will have extended to about 3.5 degrees. Somewhat confusingly, Jupiter and Venus also technically come into conjunction on Thursday, when they line up in another set of celestial coordinates (though they will appear farther apart then to observers on the ground than they did Tuesday)."

That conjunction on Thursday will rather be like the one on Tuesday night, but why? How can two objects be close to each other on two different dates, after they started to pull away from each other again? The answer is simple, and it was covered earlier in this article: perspective. It depends on where you look on earth that these planets will be closest, you can read more from the link above. In the meantime, enjoy Venus and Jupiter, they'll only remain in close conjunction for a while! [The first image is for March 14, the second for March 15]