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Look Up!

Planetary Treats
Jupiter ~ Its Smallest and Largest ...
Mercury Takes Center Stage
Three Planets Dance at Dawn
Morning Mars Grows
Celestial Delights
Large Luna Sheds Light on Our Harvest
Plus ...
Sky Lights
Printable Date Table
Moon Dances 9/18-10/18
Moon Dances 10/17-11/16
The Night Sky ~ Home Page
Libra Navigation Page

Planetary Treats

Jupiter and Its Smallest and Largest Galilean Moons

Image

This year, Jupiter's Great Red Spot has been nicely bordered by the thick white line of the Red Spot Hollow, which indents the dark South Equatorial Belt. Note the very dark red barge following behind the pale Red Spot. The North Equatorial Belt is full of turbulence, including a big blue plume. Far to the right (celestial east), Ganymede and Europa are in conjunction. S&T's Sean Walker took this image at 1:15 UT September 3, 2009. South is up. Stacked-video images like this show much more detail than you're ever likely to see visually on Jupiter.

For all of the Red Spot's central-meridian crossing times, good worldwide, use our Red Spot calculator, or print out our list for the rest of 2009.

S&T: Sean Walker

Note: Europa, the size of Earth's moon, is the smallest of Jupiter's 4 brightest Galilean moons. Ganymede, the largest Galilean moon, is also the Solar System's largest moon. In fact, Ganymede with a diameter of 3,100 miles, is larger than the planet Mercury.

Jupiter's Galilean Satellites
A Special 6-Year Geometry

Every six years, on opposite sides of Jupiter's 12-year orbit around the Sun, the Earth is positioned almost exactly above Jupiter's equator. This edge-on, high noon position, aligns the Earth with the plane of Jupiter's moons, allowing these satellites to line up in their special 6-year geometry.

At such times its four Galilean satellites [*] undergo mutual phenomena: they often get occulted and eclipsed not just by big Jupiter and its shadow but also by one another. Sky&Telescope

Note: When a celestial body hides any part of another celestial body, it occults it. When the shadow of a celestial body covers any part of another celestial body, it eclipses it. Helpful Image

In 2009, as part of the International Year of Astronomy, professional astronomers have organized a worldwide observing campaign to record as many of these events as possible. Click here for details.

Jupiter’s Moons
Sky & Telescope’s JavaScript utility helps
locate Jupiter’s four brightest satellites anytime
between January 1900–December 2100.
It also lists the satellite phenomena for the chosen day.

Jupiter's 2009 Satellite Phenomena ~ Complete List

BTW: The four largest and brightest moons of Jupiter can be seen in a dark country sky with binoculars.

Jupiter rules the night sky with a kingly brilliance that pierces the twilight. This planetary point of bright light is easily seen along the southern horizon, high in the southeast as evening begins. The planet sets in the southwest at 3:15am in the beginning of Libra and around 1:45am at its end.

Jupiter retrograde (6/15-10/11) resides in the dim constellation Capricornus and at magnitude -2.6 far outshines any stars in its vicinity. Telescopic Neptune lies near Jupiter at the northeast corner of Capricornus. 9/21-26 8pm Sky Chart Jupiter and Neptune are furthest apart October 11. Afterwards Jupiter halts its westerly retrograde movement and resumes its easterly forward motion toward Neptune.

Jupiter's orbit is now taking it farther away from the Earth. Jupiter as a result is dimming and will appear smaller during the upcoming the months.

Jupiter's distance from Earth increases nearly 10 percent during October, ending the month 442 million miles away. This results in a nearly 10 percent drop in Jupiter's apparent size ... Still, the planet appears more than twice the size of any other. That's the main reason the jovian atmosphere exhibits so much fine detail when viewed through even small telescopes. To see the most features, observe Jupiter shortly after darkness falls. The planet then stands fairly high in the sky, so we observe it through less of Earth's atmosphere. Astronomy Magazine 10/09

Planets ~ Size Comparison

Mark Your Calendar!

The Moon in the vicinity of Jupiter is truly a planetary treat. Check it out Sunday-Wednesday, September 27-30. The evening's waxing Gibbous Moon lies to the right of Jupiter September 27-28, above the planet September 29 and to the left of the planet September 30 9/28 Map ~ 9/29 9pm Map. Click Moon Dances for an additional map and reflections.

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Mercury Takes Center Stage
MESSENGER Flies By Mercury ~ September 29, 2009
Mercury Has Its Best 2009 Morning Apparition
Views from Two Previous Flybys

Larger Image  (284 kB)

The above is a gallery of images from MESSENGER's first two flybys of Mercury in January and October of 2008. Highlights include the great Caloris impact basin, the largest volcano on Mercury, a strangely-elliptical impact scar, a fresh crater with spider-like rays, an impact basin with a well-developed interior structure and the interior of the Rembrandt impact basin. Full Image Description

NASA's MESSENGER spacecraft will fly by Mercury for the third and final time on September 29. MESSENGER will pass less than 142 miles above the planet's rocky surface for a final gravity assist required to enter Mercury's orbit in 2011.

As the spacecraft approaches Mercury, cameras will photograph previously unseen terrain, and as the spacecraft departs it will take high-resolution images of the southern hemisphere. Scientists expect the spacecraft's imaging system to take more than 1,500 pictures. So far, more than 90 percent of the planet's surface has been photographed. These new pictures will fill in some of the gaps and provide high-resolution imagery of targets of interest.

The spacecraft may also observe how the planet interacts with the solar wind. During this encounter, high spectral- and high spatial-resolution measurements will be taken of Mercury's super-thin atmosphere and comet-like tail, which may be strongly influenced by solar activity. NASA's Full Article

When 2008 began, only 45% of Mercury surface had been seen by spacecraft. Then the MESSENGER mission flew by Mercury twice, first on January 14, 2008 and again on October 6, 2008 capturing images of previously unseen terrain. At the end of 2008 to the present, imaging coverage of Mercury’s surface is about 90%. The MESSENGER mission still has much to look forward to, with this third Mercury flyby and with the orbiting of Mercury beginning in March 2011.

Mercury reappears in the morning sky September 28 one day before MESSENGER's final flyby of the planet. Mercury is on center stage during its best morning apparition for 2009.

BTW: Mercury halts its retrograde motion September 29.

The planet rises in the east at 6:00am piercing through dawn's early light at magnitude 0.7. Mercury continues to brighten during Libra. The planet rises a little higher and earlier each day until it reaches greatest elongation October 6 shining at magnitude -0.6. Afterwards the planet sinks back toward the horizon rising a little later each day. See maps below. Descending Mercury has a close encounter with ascending, dimmer Saturn on October 8.

Mark Your Calendar!

October 16, Friday morning, the waning Crescent Moon lies above Mercury to the right of Venus; Saturn lies above all three. See map below. Click Moon Dances for an additional map and meditative reflections.

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Three Planets Dance at Dawn

Note: Find an unobstructed eastern horizon to view all 3 planets. You'll have no trouble seeing Venus, which is often mistaken for a UFO! Binoculars help in first spotting Mercury and faint Saturn.

BTW: Mercury is at greatest elongation the morning of 10/6. See map on the left.

Approximate Rising Times
	Oct. 6	Oct. 16
Venus	5:15am	5:30am
Mercury	5:45am	6:15am
Saturn	6:00am	5:15am
Sun	7:15am	7:15am

Rise/Set/Transit Times ~ Major Bodies

Saturn and Mercury meet on the morning of Thursday, October 8. Both planets are in exact conjunction 10/7 at 11:38pm PDT (06:38 UT 10/8).

Saturn and Venus meet on the morning of Tuesday, October 13. Both planets are in exact conjunction 10/13 at 3:52am PDT (10:52 UT).

Click Moon Dances for meditative reflections and an additional map charting the Crescent Moon.

10/16 6:30am Sky Chart
View the sky horizon to horizon.
Vary the sky chart's time and date.
Generate Sky Charts for your area.

Saturn reappears in October's morning sky, rising at 6:15am in the beginning of Libra and at 5:15am by its end. Watch the distance between Saturn and Mercury decrease. Each day they move nearer each other with their closest approach October 8. Dimmer Saturn shines at magnitude 1.1, brighter Mercury at magnitude -0.8.

October 9 Mercury sinks toward the Sun, and Saturn rises toward Venus, which is sinking toward the horizon. Saturn and Venus continue moving toward each other with their closest approach October 13. By October 16 Saturn lies above Venus paired with the waning Crescent Moon and Mercury lies below all three, as shown in the map above.

Venus rises in the east around 5:00am in the beginning of Libra and at 5:30am by its end. At magnitude -3.9 Venus dazzles, and thanks to the later sunrises, the planet remains in a darker sky longer. As Libra begins, look for Regulus, the heart star of Leo the Lion, west of Venus 5:15am - 6:15am. 10/1 6:15am Map October 9 Venus exits the Lion's den to enter the constellation of Virgo the Virgin. The dim stars of Virgo will be difficult to see.

Morning Mars Grows ~ Its Details Are Coming into View
Telescopic Mars ~ September 21, 2009

Original Smaller Image

South is up.

Mars is gradually growing bigger and brighter in the morning sky. The planet was still only 6.3 arcseconds [*] in diameter when S&T's [Sky&Telescope's] Sean Walker took this stacked-video image on the morning of September 21st, but recognizable details are coming into high-resolution imagers' views. South is up. On the right (the disk's celestial east or following side), the diagonal dark band of Sinus Sabaeus ends at Sinus Meridiani near the limb. At left, dark Syrtis Major is approaching the sunset terminator. Bright Hellas is near top.

Note the north polar clouds. In coming months, as Martian northern winter gives way to spring, the clouds should clear to reveal the bright white north polar cap. Walker used a 12.5-inch reflector and RGB color filters.

S&T: Sean Walker

Labelled Hubble Image
Use this image for orientation.
South is down.

Current Missions to Mars ~ All Missions to Mars

Mars rises in the east around 1:00am in the beginning of Libra and at 12:15am by its end. It lies more than 1/2 way to the zenith at dawn.

The Red Planet lies in the constellation of the Gemini Twins, to the right (south) of Castor and Pollux as Libra begins. Shining at magnitude 0.7 it is brighter than the Twin stars, Castor and Pollux. During Libra, watch Mars transit the Gemini Twins and enter the constellation Cancer.

Mars is approaching Earth and will continue to grow in size and brightness over the upcoming months. Much better views of our Red Planet occur at the end of the year. Mars reaches opposition in January 2010.

Mark Your Calendar!

Sunday, October 11 predawn's Last Quarter Moon approaches Mars from the west. 10/11 Map The following morning, Monday, October 12, the waning Crescent Moon lies in a diagonal alignment with the Gemini Twin stars near Mars. 10/12 Map ~ 10/12 5:30am Sky Chart Click Moon Dances for an additional map and meditative reflections.

By mid-October Mars enters the constellation Cancer and lies below (southeast) of the Gemini Twins. The movement of Mars shifts the shape of the Red Triad formed by the Red Planet, red Aldebaran the eye of Taurus the Bull, and red Betelgeuse the shoulder star of Orion the Hunter. The Orionid meteor shower peaks within the Red Triad, Wednesday morning, October 21! Look southeast 2:00am - dawn. 10/21 2am Map

Predawn Saturday, October 31, Mars enters the Beehive (M44) star cluster at the heart of Cancer. Get out those binoculars to see the bees! Beehive-Mars Map

The printable date table includes additional events through 10/23.

The Planets
Is it a planet? ... What planet? When you look up at the night sky, how do you know you are looking at a planet? Learn what a plutoid is. Click here.

 

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Celestial Delights

The Harvest Full Moon rises as the Sun is setting.

The Harvest Moon because of its closer angle to the horizon appears to loom extra large when it rises ... a well known illusion. In fact the Moon is actually closer to the Earth when it is highest in the sky!

Harvest Moon Images: Michael Myers

5 Harvest Moon Nights?!

Check it out October 2-6! Traditionally the Harvest Moon lasts more than one night. It includes the two almost Full Moons two nights before the official Full Moon and the two almost full Moons two nights after. Note: These 5 rising Moons tend to be more colorful because we see them through a thicker atmosphere than when they are overhead. The more polluted the atmosphere the more Luna blushes! A large, colorful Luna for 5 nights is definitely a treat to be harvested!

Global Meditation

Strengthen the light grid of planet Earth by participating in the Libra Full Moon Divine Identification Global Meditation.

Click Moon Dances for a Full Moon map and reflections.

May your harvest be delicious and bountiful.
May it serve the greatest good!

Printable Date Table
Lunar Cycle 9/18/09-10/18
(Can be used through 10/23)

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I'd like to know your thoughts about The Night Sky and
if you'd like reminders to Look Up! ...
send me an email.
May your Night Sky traveling always be filled
with Celestial Delights and Treats!
Susan Sun

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