AMATEUR ASTRONOMY:
TRIPLE PLAY IN THE MORNING SKY:


Assuming you get up before the Sun does, which isn't hard this time of year, there is an interesting sight in the eastern sky. Given good conditions the three planets Mercury, Venus and Saturn will be visible at the same time. Here's the story from that great site Space.com.
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Planet Triple Feature:
Venus, Saturn and Mercury Visible at Dawn This Week
By Geoff Gaherty
Early risers this week will be treated to a spectacular display of planets and bright stars as Venus, Mercury and Saturn take center stage in the predawn sky.

Half an hour before sunrise, three of the brightest planets will stretch across the eastern sky, further enhanced by the presence of two first magnitude stars, blue-white Spica and deep red Antares.

The sky map above shows how Mercury, Venus and Saturn will appear before sunrise in the eastern and southeastern sky.

The first object to attract your attention will be the planet Venus, outshining everything in the sky except the sun and moon. In a small telescope, Venus will appear as a tiny half moon as it approaches its greatest apparent distance from the sun on Saturday, Jan. 8.

Second in brightness will be the elusive planet Mercury, well below and to the left of Venus, close to the horizon. Do not confuse it with the red giant star Antares, almost directly below Venus.

You may need binoculars to spot Mercury in the bright dawn sky. This is not a favorable apparition of Mercury because of the shallow angle that the ecliptic (the path of the sun through the sky) makes with the horizon. Mercury also appears in a telescope as a tiny half moon, with the greatest elongation being on Sunday, Jan. 9.

Finally, above and to the right of Venus rides the planet Saturn, and, just below it, the brightest star in the constellation Virgo: Spica. In a telescope magnifying more than 25 times you should be able to see Saturn's famous rings, although magnification of around 200 times is needed to see the details.

Whenever you view Saturn in a telescope, be on the lookout for its retinue of moons. Even the smallest telescope will show its largest moon Titan, and larger telescopes will show half a dozen more.

AMATEUR ASTRONOMY:

TRIPLE CONJUNCTION THIS EVENING:

Yesterday the planet Mercury reached its greatest elongation , 27 degrees,(its highest above the horizon), but today it is still quite visible in the evening twilight. During the past week Mercury has formed a triangle in the evening sky with the planets Venus and Mars, and tonight Venus and mars make their closest approach, being only 18 arc-minutes from each other. Venus, shining at a magnitude of -3.9, will be the brightest of the trio, Mercury will have a magnitude of -0.2 and Mars, the dimmest of the pair, will shine at about 1.7. The diagram to the left shows how the planets will be on a line of sight this evening.

Mars will be located just slightly left of and below Venus, and Mercury will be below the air and to the left. The bright star Spica will also be visible further to the left. You will need binoculars or a moderate power telescope to view the trio because of the closeness of Mars and Venus and because of the interference of twilight. People living further south than Canada will have a better chance of viewing as the planets will appear higher above the horizon to them. Conditions are likely to be overcast here in Winnipeg, but people elsewhere may have better luck.

Good viewing.

A FIVE PLANET PARADE:

Through this early part of June the five visible planets will be observable.

VENUS:

Even though Venus reaches its greatest elongation (distance from the sun) this Saturday the planet is already rising less and less in the evening sky each night. The planet is presently located at the crossover from Gemini to Cancer and shines with a bright magnitude 0f -4.4. Venus is the second brightest object in the night sky after the Moon. The planet is presently at a waning half phase and as it enters its waning crescent phase in early July the apparent size of the disc will double from is apparent size as of May 1st. As the crescent of Venus gets thinner and thinner by late July, early August, it will have grown from an apparent size of 16 arc seconds on May 1st to 50 arc seconds.

The end of this month will see a brilliant conjunction on the evening of June 30th when Venus and Saturn pass within 2/3rds of a degree of each other. This will be the closest planetary conjunction of the year and will be best viewed due west between 10pm and 11pm that evening. The two planets will be close enough to be both visible in the eyepiece of a moderate power telescope.

MERCURY:

Though it is presently sinking towards the horizon Mercury is still visible in the western twilight until mid-June. it passed its greatest elongation on June 1st when it shone with a magnitude of +0.4. It now is about +1.2 in magnitude. From 10pm to 11pm for the next few days Mercury can be seen very low in the northwestern sky, to the right and below Venus.

SATURN

As said above Saturn will pass in conjunction with Venus on the evening of June 30th. Saturn is in the constellations Leo , to the east of the position of Venus. Saturn is presently setting before midnight, and it will set earlier and earlier as the month goes on. even though the rings present a good view because of a 17 degree tilt the features of the planet will be less and less visible as the month goes on because the closeness of the horizon will blur the detail. Presently Saturn shines at magnitude +0.5.

JUPITER:

The planet Jupiter is now much brighter than Saturn at magnitude -2.6. This planet reached opposition on June 5th when it began to rise just as the sun set. You will find it in the southeastern to southern sky throughout the nights in the constellation Ophiuchus. This constellation lays on and just above the ecliptic between the constellations of Libra to the west and Sagittarius to the east. Jupiter is usually the second brightest planet after Venus. Its distance from Earth is compensated by the fact that its surface area is 130 times that of Venus. Jupiter will never rise too high in the sky this month(20 degrees elevation at max, and that makes telescopic viewing difficult. Early next Saturday morning here in western North America two of Jupiter's Galilean moons will cast their shadows on the planet's face at the same time. Depending on location this will occur anywhere from 2:17 to 3:03 am this Saturday. This will be a good time for telescopic observation of this planet.

MARS:

This month the planet Mars can be observed at +0.8 magnitude in the constellation Pisces. This means that it lays low in the east in the hours just before sunrise. Mars is presently just to the east of the waning crescent Moon in the hours before dawn, but by June 11th it will have passed to the west, rising earlier and higher throughout the summer.

MERCURY'S LIQUID CORE:

Mercury. The first planet from the sun, laying at a distance of 0.3871 au from Sol, about 1/3rd of the distance from the Sun to Earth. Mercury has a diameter of 4,878 km, once more about 1/3d of the diameter of Earth but a mass of only 5.53% that of our planet. Its gravity is only about 28.4% that of the Earth, and its year is only about 88 days. Its rotation, however, is slower. A Mercurian day is about 59 Earth days. It's this rotation that is important in the latest discovery about Mercury. As reported in the May 4th edition of Science magazine, the journal of the AAAS, a team of astronomers from Cornell University measured small twists in the planet's rotation. They did this by sending a radio signal to reflect off the planet from a station at Goldstone, California and catching the signal again at another station in Green Bank, West Virginia.Other signals were also sent from the Arecibo Observatory in Puerto Rico and analysed at Goldstone. Their conclusion after 5 years of observation was that their values were twice as large as they would be if Mercury's core was solid. Jean-Luc Margot of Cornell states that they have a 95% confidence level in their results which are best interpreted as the result of Mercury having at least a partially molten core.

This explains the results of the flyby of Mariner 10 thirty years ago which detected a small magnetic field around the planet, something that simply couldn't occur if the planet had a solid core. The speculation is that lighter elements such as sulphur are present in Mercury's core in amounts substantial enough to lower its melting point enough to produce a magma. This challenges the standard model of planet formation which says that the terrestrial planets such as Mars, Earth, Venus and Mercury formed from heavier elements with high melting points that condensed near to the Sun while the outer planets formed in zones where lighter elements could condense. The speculation that explains this anomaly is that there was some sort of "mixing" in the early solar system whereby planetesimals carrying lighter elements were transported into the inner solar system where they were part of planet formation.

Mercury will be studied further when NASA's Messenger spacecraft makes its first flyby in 2008.

Mercury (Greek- Hermes) was the messenger of the gods and patron of merchants, messengers, lawyers and thieves. Only the "messengers" don't fit in the above lot. It solar facing surface is about 400 degrees centigrade while the far side is -170 degrees. Worse than a Manitoba day. The very eccentric orbit of Mercury and its high variation in speed would produce some strange effects if you were standing on the surface (with nuclear sunblock of course). The Sun would be seen to rise, stop, back up and set in the east, rise again, move to the west, set again, rise in the west and finally set in the east. Seems like the Sun can't make up its mind.

Mercury presently cannot be viewed, but it will appear again in the evening sky after the sun sets in late May and early June.

Interesting Conjunction Upcoming:
I've already mentioned the upcoming Leonid Meteor Shower due for Dec. 13th and 14th. Another interesting astronomical events will be happening at about the same time, Dec. 7th to 14th actually. This is a triple conjunction of the planets Mercury, Mars and Jupiter in the constellation of Scorpio. The magnitudes of the three planets will be Jupiter: -1.7, Mercury: -0.6 and Mars: +1.5. As you can gather from this Mars will be quite faint, and you will need a good pair of binoculars to spot it. This is compounded by the fact that the best time for viewing will be at about 6:30 AM, and the trio will be quite low in the southeast.
There will be 40 triple conjunctions in the period 1980 to 2050 ie about one every 21 months. Some of these, however, are impossible to observe. The unique aspect of the upcoming one this Dec. is that it will be the "tightest" of any of the events ie the planets will be the closest to each other as compared to other conjunctions. The relative positions of the planets will change over the course of the week of the event.

Transit Mercury:
There's an interesting astronomical event coming up on Nov 8th. This is the transit of Mercury across the disc of the sun. Mercury will transit the sun 14 times in this century, so,if you are ancient like I am, try to catch this one. For a in depth view see the Nasa web page for a web view of the transit if you can't set up a safe viewing mechanism- or if the weather isn't right in your locality. You can observe the transit directly providing that you have the proper filters on your telescope. The transit will be observable from the south Pacific through to the Western area of the NA continent. It will begin at 2:12 Eastern Standard Time, 11.12 Pacific Standard Time and will last about 3 hours.
Look up and wonder,
Molly