Show #30: Mercury!

Carpe Noctem - Seize the Night! Week of Oct. 16, 2006

ARCTURUS IN AUTUMN

When, in the gold October dusk, I saw you near to setting,
Arcturus, bringer of spring,
Lord of the summer nights, leaving us now in autumn,
Having no pity on our withering;

Oh, then I knew at last that my own autumn was upon me,
I felt it in my blood,
Restless as dwindling streams that still remember
The music of their flood. There in the thickening dark a wind-bent tree above me
Loosed its last leaves in flight--
I saw you sink and vanish, pitiless Arcturus,
You will not stay to share our lengthening night.

Sara Teasdale, 1926 (TOAOAL-II, pg. 1245)

Listener Question

Dan wanted directions for finding the Andromeda galaxy! I like to start with Alpheratz (al-FEE-rahts) the corner star in the great square of Pegasus shared by both constellations. This is the corner closes to Perseus and Cassiopeia. There is a long slender "V" with the brighter of the two track further away from Cassiopeia. If you start at Alpheratz, jump two stars down the brighter track to Mirach. The jump towards Cassiopeia two stars and stop. M31, the Andromeda galaxy, is just a nudge to the east. You will have 3 galaxies right there, M31, M32 and M110.

If you are having problems with faint stars another way to find M31 is to follow Cassiopeia. Start by finding Cassiopeia, if you draw a "W" on paper from left to right you make 4 lines resulting in 2 "V"s (no vendetta here)the second "V" points straight to Mirach then just back up a quarter of the way and shift east. M31 from the city looks nothing like the pictures she huge smear in the telescope with a very bright center. Give yourself time and dark skies to improve her view.

photo courtesy of: NASA Mariner 10

Feature Attraction - Mercury

Historical/Myological Facts

• Mercury was the Roman god of trade and commerce, in the same vein as Hermes of the Greeks, the messenger
• In India Mercury was called Buddha
• Mayans charted the motion of the planet Mercury as well; records of their detailed observations are found in the Dresden Codex. These include the appearance of Mercury as a morning star in 733 B.C. and as an evening star in 727. The Mayans also calculated that Mercury would rise and set in the same place in the sky every 2,200 days
• Translations from surviving cuneiform tablets reveal that Mercury was designated by many names, including that transcribed by archaeologists as MulUDU.IDIM.GU.UD. Mercury was often associated with Nabu, or Ninurta, the god of water and writing. Later, in Akkadian, it became known as Shikhtu, meaning "jumpy"
• For the Egyptian Mercury was called Thoth, the great measurer - a divinity associated with knowledge, and the inventor of speech, writing, and arithmetic
• For the northern ancestors, Mercury was named Odin, the supreme god. Often referred to as the god of wisdom, magic, and war, and the inventor of runes, his name means "inspired one". Odin was worshiped throughout northern Europe (including Britain), wherever the Vikings and other Nordic peoples settled. Odin was also known as Woden, and it is from this form that the English word for Wednesday is derived

  450 B.C. the Greeks started studying the motions of the planets and using geometry to measure the size of the Earth, Sun and Moon. Mercury was known by two different names, associated with its evening and morning appearances. These were Apollo (god of truth, the arts, archery, plagues, and divination) and Hermes (god of writing and messenger to the other gods).

Fast Facts!

• Mercury is the nearest planet to the sun. It has the most extreme contrast in temperature between day (430°C) and night (-180°C) in the solar system. Daytime temperatures are high enough to melt zinc and tin.
• BUT! Mercury is not the hottest planet, Venus is due to its heat trapping atmosphere
• Mercury's axis of rotation is oriented nearly perpendicular to the planet's orbit (axial tilt=0), so that in the polar regions sunlight strikes the surface at a constant grazing angle. The interiors of large craters at the poles are permanently shadowed and remain perpetually cold, below -212ºC (-350° F). Amazingly, radar observations of Mercury's north pole by Arecebo(a region not mapped by Mariner 10) show evidence of water ice in the protected shadows of some craters.
• Mercury's orbit is highly eccentric; at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million. 
• Pluto has the most elongated orbit, two-thirds further from the Sun at aphelion than at perihelion.
• Mercury has virtually no atmosphere, meaning life as we know it is impossible.
• Mercury rotates three times for every two orbits of the sun
• This fact and the high eccentricity of Mercury's orbit would produce very strange effects for an observer on Mercury's surface. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky. Observers at other points on Mercury's surface would see different but equally bizarre motions.
• Mercury is the second densest major body in the solar system, after Earth. Actually Earth's density is due in part to gravitational compression; if not for this, Mercury would be denser than Earth. This indicates that Mercury's dense iron core is relatively larger than Earth's, probably comprising the majority of the planet. Mercury therefore has only a relatively thin silicate mantle and crust.
• Only one spacecraft has been to mercury, Mariner 10, passing three times in 1974-75.
• However NASA's Messenger is on the way, launched in August 2004, and will fly by three times and then enter mercury orbit in March 2011. Then in 2012, ESA/ISAS's BepiColombo will be launched, also into mercurian orbit.
• Because of mercury's proximity to the sun, it cannot safely be photographed by the Hubble Space Telescope.
• Mercurian atmosphere is thin enough to be described as an exosphere, meaning the constituent atoms never collide. The identified elements in the exosphere are sodium, potassium, hydrogen, oxygen and neon. Ions and high frequency electromagnetic radiation from the sun are responsible for dislodging the atoms in the exosphere.
• Mass (kg) 3.302x1023
• Diameter is 4,880 kilometers (3,032 miles) (32% that of Earth) 2nd smallest of the classical planets now the smallest
• Perihelion (km) 46.00x106
• Aphelion (km) 69.82x106
• Length of day (hours) 4222.6

Why care about Mercury?

It offers a chance to examine another outcome of the processes that also produced Earth, Venus and Mars.

Learning how Mercury ended up the densest planet (after correcting for internal pressures) will tell us much about planetary formation.

Discovering how Mercury has sustained a magnetic field while larger bodies either have lost an earlier field (as Mars did) or have no present field and no record of a past field (Venus) will help us to understand magnetic field generation in our own planet.

Mercury also has the thinnest atmosphere among all the terrestrial planets and an incredibly wide temperature range. In fact, temperatures vary from nearly the highest in the solar system (at the equator) to among the coldest (in the permanently shadowed areas where ice deposits seem to lurk). Documenting the nature of Mercury's tenuous and changeable atmosphere and the composition of its mysterious polar deposits - thought by many to consist of water ice - will give us new insight into the volatile materials in the inner solar system.

Transit of Mercury Nov. 8 2006

Get more information about the Transit of Mercury: Wikipedia,
HM Nautical Almanac,
"Mr. Eclipse"

Viewing the transit safely!
Build a solar filter Sources for Baader film (http://www.baader-planetarium.com/sofifolie/details_e.htm#distributor)

Fun Mercury Tools

A DAY on Mercury
Visualizing a Mecurian Orbit

Planets

Evening Planets

• Mercury - Mag 0.0 in Libra. Mark your calendars for inferior conjunction and visible transit on Nov. 8th!
• Jupiter - Mag -1.6 in Libra. Clearly visible low in the sky just after sunset. Any telescope can reveal its two widest cloud bands and four Galilean satellites.
  
  
  
  images courtesy of: Stellarium software
• Pluto - Mag +14.0 in Ophiuchus
• Uranus - Mag +5.8 in Aquarius Uranus is best seen in a dark moonless sky away from artificial lighting. It may be seen looking like a very faint star to the dark-adapted naked eye that shimmers in and out of visibility just over 1 degree east of Lambda Aquarii. Find the tipped over letter Y of Aquarius, go 4 thumbwidths southeast to find Lambda, and then look pinky nail east.
• Neptune - Mag +7.9 in Capricorn 1 degree north of the +4.3 magnitude star Iota Capricorni

Too close to the sun..

• Mars - Mag +1.6 is at the western end of Virgo. You will have to look hard in the haze of the horizon and it will help to be closer to the equator.
• Venus - Mag -3.8 in Virgo.

Morning Planets

• Saturn - Mag +0.6 on the western edge of Leo!

Shall we be sassy? Dwarf Planets..er...Minor Planets...er...Icy Dwarfs....er...um...hmmmm

• 1 Ceres +7.9 mag in Piscis Austeralis 18.5 degrees West of Formalhaut
• Eris mag +19 in central Cetus

Constellations

Circinus -Circinus was invented by Lacaille during his stay at the Cape of Good Hope between 1751 and 1752. Latin for compass, is one of the small southern (declination -50 to -60 degrees) constellations. It represents a tool used in drawing maps and as such should not be confused with Pyxis, a constellation associated with a ship's compass.

Pyxis(-Latin for box as in Pyxis Navigatum [lit. Sailor's Box, a compass]) is a minor southern constellation introduced by Nicolas Louis de Lacaille under the name Pyxis Nautica. It is perhaps supposed to represent the compass of Argo Navis but not formally a part of Argo Navis; that is, the stars in it have their own independent Bayer designations (unlike Carina, Puppis and Vela which retained and split among themselves the Bayer designations from Argo).

Vulpecula - (vul-pek-U-lu) the Fox, It was originally known as Vulpecula cum ansere = "the Fox with the Goose" created by Hevelius, but the goose no longer appears on star charts but the name remains in Alpha Vulpeculae is a red giant of spectral class M0 and has apparent magnitude +4.4 the least faint star in this very faint constellation.

However! :-) As faint as this constellation is it has too noteworthy features; "The Coathanger" more formally named Brocchi's Cluster (Collinder 399) and M27, the Dumbbell Nebula, is a large, bright planetary nebula which was discovered by the French astronomer Charles Messier in 1764 as the very first object of its kind. Find them!

Viewing

October 14 -Last Quarter Moon 00:26 UT
15 -Moon near the Beehive cluster -M44
17 -Mercury at greatest elongation (4 UT) 25 deg east of the sun in the evening sky
17-19 Algol complete a full cycle from min to max to min it's nice and dark to see if you can catch this variable
19 -Moon at apogee (the furtherest point from Earth 406,500 km)
21 -Orionid meteor shower -peak 14:05 UT
22 -New Moon 5:14 UT
24 -Waxing crescent moon 10 degrees SE of Jupiter and Mercury 3.5ish degrees S of Jupiter

Naked eye -
NH: Time to get up early! Winter triangle, the Hyades (head of Taurus) and the Winter hexagon
SH: Large and Small Magellanic clouds, 47 Tucanae

Binocular -
NH: Star hop your way to the Andromeda Galaxy.
SH: NGC 362 globular cluster in Tucanae

Telescope -
Comet Swan currently in Canes Venatici. From the city it looks like a faint nebulous globular cluster! I did NOT see this! Aerith.net, Heavens-above.com
Comet C2006 T1 (Levy) currently in Leo. Wait until mid-week for the moon to get out of the way.
M27 - The Dumbell Nebula in Vulpecula
NH: M33 in Triangulum directly opposite Mirach from M31 - and with it NGC 604 and for a real challenge NGC 595, NGC 592 and NGC 588!
SH: Circinus Galaxy - NGC 346
in SMC -find it NGC 2070 - the Tarantula Nebula -find it Southern hemisphere challenge object very low surface brightness Mag 12.9
NGC 5715 9.8 Open Cluster

The Moon

Images created with Lunar Phase Pro

Our beautiful lunar photos are courtesy of Frank Barrett at celestialwonders.com I recommend visiting his site and checking out his lunar phase photos. You can zoom in for more detail.

Object	Latitude	Longitude	Comments
Waning Crescent Group
Crater Grimaldi	-5.5	-68.3	Francesco Maria; Italian astronomer, physicist (1618-1663)
Crater Riccioli	-3.3	-74.6	Giovanni Battista; Italian astronomer (1598-1671)
Montes Cordillera	-17.5	-81.6	Spanish for "mountain chain"
Waxing Crescent Group
Crater Langrenus	-8.9	61.1
In between...			Lohse (German astronomer), Vendelinus (Belgian astronomer), Petavius B., Wrottesley (British Astronomer)
Crater Petavius	-25.1	60.4

Remember latitudes that are negative (-) are South and longitudes that are negative (-) are West!

Comets

Comets for the Month.

Check out the Sky Hound site.

"One touch of nature makes the whole world kin"
-- Shakespeare

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Music

Danielle French - Till We Meet Again
Bob Kirkpatrick -"I hate the Rain"

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