Constellation of the Month: Microscopium

Microscopium with its borders, asterism and depicted art (Source: IAU.org, Stellarium, ret. 2012)

     Microscopium (Lacaille Family) is a small and faint constellation in the Southern Hemisphere bordered by Capricornus at its north, Indus at its south, Saggitarius at its west, and Piscis Austrinus and Grus at its east. It covers approximately 210 degrees of sky. Aside from 5 faint stars in its asterism, it also had 13 Bayer/Flamsteed designated stars within its borders.

     This constellation was named after the microscope, as the name suggests, by Nicolas Louis de Lacaille. Since Lacaille was a man of science, he used scientific instruments in naming his newly created constellations and added them in his southern star catalog, the Coelum Australe Stelliferum. No mythological stories are related to this constellation since it is considered “new” and did not even exist during the Greek period.

Notable Star/s:

     Gamma Microscopii (γ Mic) – It is the brightest star in the constellation with an apparent visual magnitude of 4.677. It is a G-type giant 220-light years away from the sun. It is believed that about 3.8 million years ago, gamma Microscopii was only six light-years distant from the Sun. This would have made it brighter than Sirius, alpha Canis Majoris, currently the brightest star in the sky.

     Theta 1 Microscopii and Theta 2 Microscopii (θ1 Mic and θ2 Mic) – theta 1 Mic is a variable star and together with theta 2 Mic forms a binary star system.

     WASP-7 (HD 197286) – It is known to have an exoplanet revolving around it named HD 197286b

Other Notable Celestial Object/s:

     HD 197286 b – It is an extrasolar revolving around WASP-7 discovered in 2008. It completes its orbit around its star for 4.95 Earth years and has a Jovian mass scale of 1.28.

     NGC 6925 – This faint inclined spiral galaxy is known to contain a megamaser.

Trivia:

1.) Although ancient Greek ignored this constellation due to its faintness, it is believed that Chinese had imagined one Constellation on this area. They called it Jiukan, meaning nine water wells or canals. Water from Jiukan would no doubt have been used to irrigate Tiantian, the Emperor’s farmland in Capricornus to the north.

2.) It was on the 2nd edition of Lacaille’s chart that the name of the constellation was Latinized into Microscopium. Lacaille first called it le Microscope.

Lacaille’s original depiction of Microscopium (Source: http://www.ianridpath.com/startales/microlacaille.htm, ret. 2012)

Prepared by Marc Mapalo

References:

Constellations: Microscopium 'the Microscope'. (n.d.). Retrieved from h2g2: http://h2g2.com/dna/h2g2/alabaster/A43082138

Microscopium Constellation. (n.d.). Retrieved from TopAstronomer.com: http://www.topastronomer.com/StarCharts/Constellations/Microscopium.php

Plotner, T. (2008, December 3). Microscopium. Retrieved from Universe Today: http://www.universetoday.com/21809/microscopium/

Ridpath, I. (n.d.). Microscopium. Retrieved from Ian Ridpath: Star Tales: http://www.ianridpath.com/startales/microscopium.htm

Photo Sources:

Ridpath, I. (n.d.). Lacaille's Microscopium. Retrieved from Ian Ridpath: Star Tales: http://www.ianridpath.com/startales/microlacaille.htm

2013 Astronomical Events

     The highlights of year 2013 include two comets with the potential of being impressive naked eye objects on the first and last quarter of the year. Most of the comets are not bright enough to be seen by the unaided eye and thus rare. In the last two decades, there have been only four bright comets – Comet Hyakutake of 1996, Comet Hale Bopp of 1997,  Comet McNaught of 2007, and Comet Lovejoy of 2011. This year’s comets, Comet PanSTTARS and Comet ISON, could possibly be so bright with Comet ISON outshining the Moon.

Aside from the two would-be great comets, here are some of the most awaited sky events of 2013:

January 3-4 Quadrantid Meteor Shower

     After the spectacle of New Year fireworks in the sky, another show is yet to display on January 3 and 4. The first meteor shower of the year, Quadrantids, was named after an obsolete constellation Quadrans Muralis which was once located between the constellations of Bootes and Draco. This shower display will offer up to 40 meteors per hour at their peak. The Quadrantids meteors peak for a very short time, lasting only hours, so it is advised to wait the whole night or after midnight and not miss them. They can be seen radiating near the constellation Bootes and the Big Dipper, rising northeast in the sky. The company of the waning gibbous Moon will make the faint meteors harder to spot but this annual meteor shower might still give a decent show as it can produce fireballs at above average hourly rates.

March Comet PanSTARRS

     

     The comet C/2011 L4 or comet PANSTARRS (Panoramic Survey Telescope and Rapid Response System) has a high chance of being a fine naked eye object on March. A comet is composed of rock and ice which vaporizes as it approaches the Sun. This causes the comet to become brighter and produce a bright tail which always points away from the Sun.  Although not as prominent as the much awaited comet ISON on November, comet PanSTARRS will still be a fantastic sight for enthusiasts and can be a warm-up observation for comet ISON. Because of the unpredictability of comets, expect Comet PANSTARRS to be as bright as Vega particularly on March 9 as it enters perihelion – point where it is nearest to the Sun.

     Observe Comet PanSTARRS in the west as it gets brighter as the Sun sets, leaving about an hour for a beautiful display before the comet finally sets. And if the comet tail develops well, expect it to extend above the horizon after the comet sets. On March 14, the crescent Moon will join the view and rest near the comet tail.

March 28 Occultation of Spica by the Moon

    There will be many instances where Spica, the brightest star in the constellation Virgo, will be occulted by the Moon this year. Occultation is a phenomenon where an object is hidden when another object passes between it and an observer. This time, the Moon will pass between us and the first magnitude star Spica. The star will hide behind the Moon and will appear on the thin dark limb of the Moon. Lunar occultations are often observed and timed by amateur astronomers to learn more about the topography of the Moon.

     In the Philippines, the most observable occultation of Spica will be on March 28.

April 21-22 Lyrid Meteor Shower

    

     After a long calm night sky for meteor showers, another shower is now ready for a show. This year’s Lyrid meteor shower might put up a great display despite the presence of the waxing gibbous Moon. Lyrids offers up to 20 meteors per hour at peak and can be best viewed hours after midnight and when the Moon sets. They can be seen radiating from the constellation Lyra, at northeast near the Milky Way band. Occasionally, the Lyrids intensifies and offers a meteor storm like the historical 700 meteors per hour of Lyrids 1803. 

April 25 Partial Lunar Eclipse

  

   A partial lunar eclipse, the first of the three lunar eclipses this year, will occur around 8PM UT on April 25. This event will be one of the shortest partial lunar eclipses, lasting less than 30 minutes, with just 0.5 arc minutes or about 0.3%  of the Moon entering the Earth’s umbra – darkest part of its shadow.

     In the Philippines, only the penumbral eclipse can be observed. This will cause a light dimming on the Moon as it enters the Earth’s penumbra – the lighter shadow. The greatest eclipse will occur at around 4:09AM (PHT) on April 26. The remaining two lunar eclipses of the year, May and October penumbral lunar eclipses, will not be visible in the Philippines. 

April 28 Saturn at Opposition

    

     Saturn will be at its brightest and will appear much larger when it reaches opposition – when the position of Saturn and Sun in the sky is directly opposite and when it is closest to the Earth. Saturn will be seen rising as the sun sets. This is the best time to take pictures of the stunning planet with its rings.

May 5-6 Eta Aquarids

    Eta Aquarid meteor shower usually produce about 10-20 meteors per hour at peak but can be unpredictable and reach a higher rate. They can be seen radiating from the constellation Aquarius, just look at the east from midnight to dawn. The crescent Moon will also give way for this spectacular show.

May 10 Annular Solar Eclipse

     An annular solar eclipse will occur on May 10 and will be visible from Northern Australia and Pacific Ocean. An annular solar eclipse occurs when the Moon’s apparent diameter is smaller than the Sun, allowing the Sun to look like a ring when the Moon passes directly between the Earth and the Sun.

     Observers from the southern part of Philippines can only witness a partial solar eclipse. Just wait an hour or less after the sun rises. Be careful in observing the eclipse and use proper viewing methods.

May 26 -31 Jupiter, Mercury, and Venus Planetary Grouping

   

     Three of the brightest naked eye objects in the night sky – Jupiter, Mercury, and Venus – will cluster in the last week of May to put a lovely view. These planets will be around 2 degrees away from each other and can be seen just after the sunset. There will be around 30 minutes leeway before the grouping set so watch out for the parade.

     On May 28, the two brightest night sky objects (aside from the Moon), Venus and Jupiter will shine very close together at only 1 degree apart.

     On May 31, the three can be seen lining up within 10 degrees looking like a bigger and brighter version of Orion’s belt.

November 3 Hybrid Solar Eclipse

     A special type of eclipse will occur on November 3. Hybrid solar eclipses are also called annular-solar eclipses. This kind of eclipse occurs when the vertex of Moon’s shadow is near the surface of the Earth. Observers from the central path of the shadow witness an annular eclipse, when the vertex of the Moon’s shadow fell short in reaching the Earth. It will become total when the vertex of the shadow eventually touches the Earth’s surface. This feature is also caused by the topography of the Earth – having low and high land areas.

     The path of the greatest eclipse will pass across the North Atlantic and equatorial Africa. Sadly, this is another event that will be missed by observers in the Philippines.

Comet C/1995 O1 or Comet Hale-Bopp  (1997)
(en.wikipedia.org)

Nov 28 Comet ISON

     Comet Hale-Bopp of 1997 will not be the brightest comet in our lifetimes if Comet C/2012 S1 or Comet ISON, named after International Scientific Optical Network, survives its close encounter with the Sun on November 28 to 29. Comet ISON will be a naked eye spectacle for weeks from November 2013 to January 2014 and it has a large potential of being so bright that it can outshine the Moon.

Dec 13 Geminid Meteor Shower

     One of the most anticipated meteor showers, Geminids, seems to be getting stronger every year. Geminids can offer up to 120 meteors per hour at their peak and can be seen radiating from the constellation Gemini. This years’ Geminids is best watched between midnight and dawn as the waxing gibbous moon exits the night sky at around 3:30AM. This will give us about 2 hours to enjoy a darker sky, thus a better show.

Prepared by Carlo Ray Selabao



Reference: 

http://earthsky.org/tonight/quadrantid-meteor-shower-before-dawn-in-early-january

http://www.space.com/15108-comet-panstarrs-skywatching-countdown-2013.html

http://www.spaceweather.com/meteors/lyrids/lyrids.html

http://eclipse.gsfc.nasa.gov/OH/OH2013.html

http://astropixels.com/ephemeris/astrocal/astrocal2013pst.html

Dec 21, 2012 is Doomsday?

The frenzy regarding the end of the world is so wide-spread that it almost seems true. There are a number of "theories" all claiming that the world will end in 2012. The most popular doomsday predictions are as follows: The collision of planet Earth to another planet; planetary and galactic alignments; solar flares that could violently erupt; and the end of the Mayan Calendar. But before we start to hoard food and artillery, let us examine where all these rumors/theories are coming from and know what the experts (specifically, the scientists from NASA) have to say.

The first "threat" is the predicted return of the planet known as Nibiru (or Planet X). It is actually from the book called The Twelfth Planet by Zechariah Sitchin. It basically tells about how aliens from Nibiru, called Anunnaki, came to the Earth and mined our natural resources to supplement their own. People who believe in the existence of Planet Nibiru say that it is causing disruption in the orbit of planets Uranus and Neptune, meaning, it is really close at hand and humanity should prepare for their doom because a giant planet is on its way to Earth for a collision course. But, do not believe it yet. If something as massive as another planet like Nibiru is indeed coming its way, NASA would have no doubt alerted us. From a scientific point of view, Nibiru is a hoax (just look at the book's title; how many planets do we have in the Solar System?). Besides, it was predicted to hit the Earth as early as May 2003---nothing happened! Just in case, NASA have a program (a survey, actually) which watches out for meteors and other celestial objects that may threaten the Earth. It is determined that for now, Earth is in no danger.

The other threat related to astronomy is the predicted planetary alignment that might cause disasters on Earth. While we admitted that this is a rare occurence, and it still makes people anxious, planets have already aligned before. The most recent planetary alignment happened in the year 2000. Did we feel anything bizarre, then? Hardly any, if people actually did. It is because it is negligible. In other words, it is another thing that we should not worry about. NASA also warns the public against believing in the Polar Shift. There are no evidences to prove that it is possible and that it can happen in the near future.

Some people further insuniate that there is going to be a galactic alignment that will happen this December. This galactic alignment, by the way, is that the Solar System will align with the center of the Milky Way as it passes through the constellation Sagittarius. Since a black hole, so some people believe, is at the center of the universe, there is a chance that we will get sucked into it because of the black hole's vacuum-like gravity. However, like the planetary alignment, this is also negligible and not precise. A black hole exists but it is so, so far away (150 quadrillion miles) from the Solar System that even if we perfectly align with it (which will not happen because the Solar System's angle will not permit it to), the effects cannot be perceived by anything or anyone. It's another doomsday prediction which is not backed up with sufficient proof to worry ourselves about.

As for the solar flares, it had been erupting for so long that numerous doomsday predictions were made about it. Some people say that we are approaching the end of Sun's 11-year cycle; that it will happen on December 21. The cycle, observed and discovered by Samuel Schwabe in 1843, is the various changes in the sun's activities which include flares and strong coronal mass ejections. These kinds of solar activities affect the Earth's radio communications, the climate, and it damages the Earth's artificial satellites. The idea of having a major solar catastrophe this Friday, Dec. 21, is misleading. The end of the cycle periodically happens every 11 years; and, in the present decade it will be on 2013. Also, NASA assured us that their will be no total blackouts.

Finally, we go to the most popular: the end of the Mayan Calendar on Dec. 21. This has almost nothing in relation to astronomy besides that Mayans calculated the dates based on their concept of astronomy back then. For the record, the Mayan calendar is cyclical. It means that the "end" is just another beginning of another cycle. Though there might be changes, it is really connected to spirituality,according to Jaime Licauco. Spirituality and astronomy are on different fields.

So, in conclusion, there is really nothing to prove that the end of the world is near! But it is better to think about how the earth is changing gradually (have you noticed natural disasters are fiercer?) because we still have climate change. That's just a friendly reminder. Have a merry Christmas and a happy New Year!

Prepared by Delwin Rose Villarey

References:

Labitzke K., Matthes K. (2003). "Eleven-year solar cycle variations in the atmosphere: observations, mechanisms and models". The Holocene 13 (3): 311–7.

Licauco, Jaime.Mayan Calendar and the end of the earth cycle. Philippine Daily Inquirer. http://showbizandstyle.inquirer.net/lifestyle/lifestyle/view/20080630-145664/Mayan-calendar-and-the-end-of-earth-cycle

NASA. Beyond 2012: Why the World Won't End. http://www.nasa.gov/topics/earth/features/2012.html

What is Planet Nibiru and is it Approaching? http://www.december212012.com/articles/PlanetX_Nibiru/What_Is_the_Planet_Nibiru_and_Is_It_Approaching.htm

Plait, Phil. "Worried About the ENd of the World on Dec. 21? Don't Be". Bad Astronomy. http://www.slate.com/blogs/bad_astronomy/2012/12/18/maya_apocalypse_2012_doomsday_end_of_the_world_prophecies_are_nonsense.html

The Geminid Meteor Shower

The Geminid meteor shower, commonly called the Geminids, is a yearly meteor shower seen from the Earth in December. It is named after the constellation Gemini where the radiant, the point from where the meteors seem to come from, is located. The Geminids are active every year from about December 6 to December 19 with the most active period at December 13 and 14.

The maximum rate, or the number of meteors that fall per hour when the shower is at its heaviest, has increased every year since the discovery of the Geminids in 1862. In 1877 the maximum rate was 15 meteors per hour, in the 1890s maximum rates reached 25 meteors per hour, and by the 1990s maximum rates were more than 80 meteors per hour.  Recent showers have seen 120-160 meteors per hour.

The meteors from the Geminids travel in relatively medium speed compared to other showers at about 35 kilometers per second making them fairly easy to spot. The meteors often appear yellowish in hue and disintegrate at heights above 38 kilometers.

This 2012, the maximum rate is predicted to be at around 120 per hour though on average it produces 50 or more meteors per hour. The new moon falls on December 13 ensuring dark nights for viewing the Geminids. The best place to view the Geminids is under a wide dark sky. It would be better if you let your eyes adapt to the darkness to better view the meteors. The Geminid radiant point lies close to the star Castor and would climb above the eastern horizon at about 7 pm. The greatest number of meteors fall at around 1 to 2 am when the radiant point is highest in the sky.

The Geminids were discovered by English and American observers in 1862. In 1947 Czechoslovakian astronomer Miroslav Plavec first determined the orbit of the stream of meteors that causes the shower He noted that the gravitational force of the planet Jupiter was causing the orbit to shift its position gradually. The earth first passed through the Geminid meteor stream in the 19th century, and the meteor stream will probably move out of the earth’s path after the 21st century.
The Geminid meteor shower is the only meteor showers to be linked to an asteroid. The parent object of the Geminid shower, 3200 Phaethon, was discovered and photographed in 1983 by the Infrared Astronomical Satellite and has the appearances of a small Earth-crossing asteroid. This object does not exhibit the usual features of a comet such as the nebulous head and long tail and so was place among the asteroids. Most researchers believe that Phaethon is the burned-out remnant of a once-active comet.

 
Prepared by Peter Singer Jr.

References:
"Geminids." Microsoft® Encarta® 2009 [DVD]. Redmond, WA: Microsoft Corporation, 2008.
"meteor and meteoroid." Encyclopædia Britannica. Encyclopædia Britannica Ultimate Reference Suite.  Chicago: Encyclopædia Britannica, 2011.
http://en.wikipedia.org/wiki/Geminids retrieved on 12/12/2012http://earthsky.org/astronomy-essentials/ten-tips-for-watching-the-geminid-meteor-shower retrieved on 12/12/2012

November Night Sky

The month of November will amplify the beauty of the pre-Christmas night sky with the numerous conjunctions between the moon and the planets, as well as the two major meteor showers that will occur this month. As we approach the December winter solstice, the constellations of Orion, Taurus, Leo and Virgo become more prominent in the sky.

Jupiter will be seen high up in Taurus in the evenings of the whole month, slowly moving westward, approaching a brightness of -2.8 and enlargening to 48 arcseconds as it does so. Saturn and Venus will constantly be visible near the east horizon at dusk, while Mars will be visible near the west horizon at sunset starting the middle of the month. 

On November 1, the moon will be in apogee (its farthest distance from the Earth in the lunar cycle it is in). The slightly smaller moon will be seen near the bright planet Jupiter. These two heavenly bodies will approach a distance of only 0.9 degrees the following day, November 2.

Between November 2 to November 7, the Taurids meteor shower will peak. Slow meteors (some may leave trails) will be coming from near the Pleiades cluster in Taurus. However, the Taurids are not expected to be spectacular this year, with only around 7 visible meteors per hour. The moon’s luminosity may outshine the faint meteors, especially since it is only due to be at last quarter on November 7.

On November 11, the moon and Venus will be at close proximity during the pre-dawn hours, being only 5 degrees apart. The next day, it is the moon and Saturn that will be in close proximity, at an even closer 4 degrees apart.

The new moon falls on November 13. Though this will not have a huge impact on skywatchers here in the Philippines, Australia and some southern Pacific islands will be experiencing a total solar eclipse. The track of the moon’s shadow is shown below.

November 14 sees a slightly bigger crescent due to perigee (closest distance of the moon to the Earth), while Venus and Virgo’s alpha star Spica will steal the pre-dawn scene the next day, November 15, by being only 1.9 degrees apart.

On November 16, the crescent moon and Mars will be visible in the west at sunset – the two being only 4 degrees apart. Mars will have a faint glow of 1.2.

On November 17, mercury will be at inferior conjunction, the new moon counterpart for planets.

The more noterworthy astronomical of November 16 and 17 however, is the peak of the Leonids meteor shower. Ten to fifteen (10-15) meteors per hour will be expected emanating from the constellation Leo. The cresent moon’s luminosity will not interfere with this meteor shower as its gibbous phase did during the Taurids.

First quarter falls on November 20.

A week later, on November 27, Venus and Saturn will be an astonishing sight by being a mere 0.6 degrees apart before sunrise, while the Moon will be only 4 degrees away from the Pleiades of Taurus during the evening.

On November 28, another apogee occurs, which coincides with a penumbral lunar eclipse. This slight darkening of the moon will occur close to Juipter and Aldebaran in Taurus.

The last noteworthy astronomical event of the month is when the moon and Jupiter approach being only 0.6 degrees apart. Jupiter nears opposition in December.

References and Image sources:

http://www.guardian.co.uk/science/2012/oct/28/starwatch-november-night-sky-orion

http://www.absoluteaxarquia.com/nightsky.html

http://yourhub.denverpost.com/denver/november-2012-eye-sky/oplUw5lOG0M0bX9EyKksaL-ugc

http://eclipse.gsfc.nasa.gov/SEmono/TSE2012/TSE2012.html

http://journeytothestars.wordpress.com/2010/11/18/the-2010-leonids-meteor-shower/

http://earthsky.org/astronomy-essentials/visible-planets-tonight-mars-jupiter-venus-saturn-mercury

http://earthsky.org/tonight/n-taurid-meteors-at-late-night-moon-venus-before-sunrise

http://earthsky.org/tonight/moonless-nights-for-november-leonid-meteors-in-2012

http://earthsky.org/tonight/jupiter-out-all-night-venus-saturn-mercury-before-sunrise

http://en.wikipedia.org/wiki/November_2012_lunar_eclipse

 

October Night Sky

October is a month for transitions. It also sets the stage for a handful of groupings involving planets and the Moon. Moreover, October marks the peak of two meteor showers. 

On October 3, Venus will pair up with Regulus, the alpha star of the constellation Leo before sunrise.

Screenshot from Stellarium Version 0.10.6.1. Location: Quezon City, Philippines

Venus will later pair up with the Moon at its waning crescent phase on October 12.

Screenshot from Stellarium Version 0.10.6.1. Location: Quezon City, Philippines

On October 4, 5 and 6, the Moon will be seen with the stationary Jupiter.

Screenshot from Stellarium Version 0.10.6.1. Location: Quezon City, Philippines

On October 8, the Moon will be at its last quarter phase. This will occur at 7:33 UTC. Also on this day at 2:00 UTC, the Draconid meteor shower will peak. The meteors will appear before the last quarter Moon rises at midnight. Hence, the observation of these meteors will not be affected. Meteors can also be observed a day earlier.

On October 15, the Moon will be at its New Moon phase. It will not be visible from the Earth since no light from the Sun is reflected to us, as the side of the Moon facing us is not lit by the Sun. This will occur at 12:02 UTC.

On October 17 and 18, Mars will be seen with the waxing crescent Moon. Mars can also be seen near Antares, the alpha star of the constellation Scorpius. Mars can be spotted before sunset.

Screenshot from Stellarium Version 0.10.6.1. Location: Quezon City, Philippines

The Orionid meteor shower, a result of the Earth passing the dust trails left by Halley ’s Comet, will peak on October 20-21. It produces peak observed rates of more than 10 per hour (ZHR=25). Nevertheless, meteors can be seen anytime from October 17 to October 25. Brighter Orionids may leave persistent trains. The radiant, the apparent source of the meteors, rises at 21h UT. [1]

On October 22, the Moon will be at its first quarter. This will occur at 03:32 UTC. However, this will not affect the observation of the Orionid meteor shower as the first quarter Moon sets before the Orionid radiant rises.

On October 25, Saturn will leave the starry skies.

On October 26, Mercury will reach its greatest evening elongation at 24° East. It will shine at -0.1 magnitude. The innermost planet in Solar System will most likely be seen at dusk, and it will be hard for the observers in the Northern Hemisphere to spot it after the sunset.

On October 29, a Full Moon will lighten the night skies. This will occur at 19:49 UTC.

At the start of the month, Venus can be seen at the constellation Leo. Later in October, it can be seen moving towards Virgo. The planet’s apparent diameter decreases, whilst its gibbous phase grows at a significant illuminated proportion. It will remain a morning star all throughout the month and for the rest of the year. The planet is 35° west of the Sun and is 28° high at sunrise as the month ends.

All throughout 2012, Jupiter can be seen near the constellation Taurus. In early October, observers can see it rising by mid-evening. Towards the end of the month, it can be seen rising after sunset. It brightens from magnitude -2.3 to -2.7 and its apparent diameter grows from 39 to 47 arcseconds.

Sources:

Society for Popular Astronomy. Sky Diary: A Summary of sky events during September and October. In: Society for Popular Astronomy [Internet]. [cited 01 October 2012]. Available from: http://www.popastro.com/documents/SkyDiary.pdf

Sea and Sky. Astronomy Calendar of Celestial Events for  Calendar Year 2012. In: The Sky [Internet] [cited 01 October 2012] Available from: http://www.seasky.org/astronomy/astronomy-calendar-2012.html

Legendary Draconid meteors best after sunset October 7. In: EarthSky: A clear voice of science article [Internet]. [cited 01 October 2012]. Available from: http://earthsky.org/tonight/legendary-draconids-boom-or-bust

October 2012 guide to the five visible planets. In: EarthSky: A clear voice of science article [Internet]. [updated 05 September 2012; cited 01 October 2012]. Available from: http://earthsky.org/astronomy-essentials/visible-planets-tonight-mars-jupiter-venus-saturn-mercury

Q6: Plate Tectonics on Venus and Mars

Q: With the recent findings that Mars exhibits plate tectonics, could Mars and Venus exhibit the same, since after all they do have volcanism?

A: Well, not neccesarily.

Let's start with the requirements of plate tectonics. First, there has to ba a driving force for plates to form and move. In our case, the driving force is the weight of our crust, and the heat from the interior. The heat makes the layer beneath the crust soft, allowing for convection currents that pull on the overlying crust. This heat is supplied by the radioactive decay of matter trapped in the core, a consequence of the large volume of matter that coalesced in Earth's early years. Heat may also be supplied by tidal forces from a nearby large body, such as those powering volcanism in Jupiter's moon Io. The tidal forces pull on the rocky material (such as how the moon pulls on our seas), creating friction that generates the heat.

Now let's tackle Mercury. Mercury does not have the sufficient mass and volume to have trapped much radioactive material necessary to power plate tectonics to this day. Tidal forces from the sun does effect Mercury's crust, but not enough to cause plate formation and movement. A 2008 survey of the planet has shown that it still has a molten core, but volcanism had ceased a long time ago. Chances that it still exhibits plate tectonics are slim.

Venus is another story. It has active volcanism, but present evidence cannot suggest that it has an active plate system. A theory proposed is that liquid water plays a role in plate tectonics, such that it "lubricates" subduction zones. A "wet" crust is also more likely to fail or create cracks and faults, since a dry crust can be strong enough to resist plate motion. The volcanoes of Venus are like the Hawaiian islands - volcanoes not connected to subduction zones.

These answers however, are based on plate tectonics as experienced here on Earth, which is why scientists were also surprised by the findings in Mars. Perhaps space geology still has a long way to go. No matter, what can be certain is that these planets did experience the familiar kind of plate tectoncis in their youth, when they were hotter and softer.

References:
http://www.umich.edu/~gs265/tecpaper.htm
http://www.news.cornell.edu/stories/May07/margot.mercury.html
http://csep10.phys.utk.edu/astr161/lect/mercury/surface.html
http://adsabs.harvard.edu/abs/2001AGUFM.U21A..09S