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Mars Observational Data, Aug 2009 - Jul 2010

Moon nr Mars, Sep 2009 - Dec 2010

Mars Oppositions, 2012-27

The Martian Seasons

Path of Mars from Aug 2009 to Jul 2010. Click for full-size image (Copyright Martin J Powell 2009)

The path of Mars against the background stars of Gemini, Cancer and Leo from August 2009 to July 2010, shown at 10-day intervals (click on the thumbnail for the full-size image). The planet's path from mid-July 2010 is continued on the Venus 2010. During this apparition, Mars described a typical, Northward-facing loop, differing somewhat from the hybrid formation (half-loop, half-zigzag) of the 2007-8 period. A close-up of the planet's path through the M44 (Praesepe) star cluster is shown below.

The star map applies to observers in the Northern hemisphere (i.e. North is up); for the Southern hemisphere view, click here (the Southern hemisphere chart should be used by observers situated south of the Tropic of Cancer [23 North]). The Milky Way is shown in dark grey; the faintest stars shown on the map have an apparent magnitude of about +4.8. Printer-friendly versions of this chart are available for Northern and Southern hemisphere views. Astronomical co-ordinates of Right Ascension (longitude, measured Eastwards in hrs:mins) and Declination (latitude, measured in degrees North or South of the celestial equator) are marked around the border of the chart.

The Mars Apparition of 2009-2010

by Martin J. Powell

Following superior conjunction on December 5th 2008 (when it passed directly behind the Sun) Mars emerged in the dawn sky in February 2009 as a relatively dim 'morning star', rising shortly before the Sun. Through the first half of 2009, the planet was best seen from the Southern hemisphere, although the planet's great distance and small apparent size during this period made it a disappointing sight when observed through telescopes. For Northern hemisphere observers, viewing circumstances were poor throughout the first half of 2009, with Mars appearing low down in the Eastern sky at dawn. Seen from the Northern hemisphere, Mars did not become a prominently visible object until late July 2009, by which time the long summer twilight was starting to recede and the planet was rising about four hours before the Sun. Viewing circumstances improved for both hemispheres as 2009 progressed.

From early 2009 through to August 2009, Mars moved steadily Eastwards (direct motion) through the following constellations, slowly brightening as its distance from Earth reduced:

Date Range

Constellation

<----- Mid-Period ----->

Apparent Magnitude

Apparent

Diameter

(arcsecs)

Solar

Elongation

2009

Feb 1 to Feb 3

Sagittarius

+1.3

3".8

15W

Feb 3 to Mar 11

Capricornus

+1.2

4".0

20W

Mar 11 to Apr 15

Aquarius

+1.2

4".2

 27W

Apr 15 to May 1

Pisces

+1.2

4".4

33W

May 1 to May 4

 

Cetus

+1.2

4".4

35W

May 4 to May 31

Pisces

+1.2

4".4

37W

May 31 to Jul 2

Aries

+1.1

4".8

44W

Jul 2 to Aug 25

Taurus

+1.1

5".2

54W

Table showing the position and apparent magnitude of Mars for the early part of the 2009-2010 apparition. The magnitudes, diameters and solar elongations listed here refer to the middle of the period in question. Mars began the apparition far to the South in Sagittarius, then ascended the ecliptic (heading Northwards) from Capricornus through to Taurus. In this and the tables which follow, the rising and setting directions of the constellations listed can be found by referring to the zodiacal constellation rise-set direction table.

On August 25th 2009, Mars crossed the boundary from Taurus, the Bull, into Gemini, the Twins. Mars brightened significantly from late September 2009 and its coloration began to appear more distinct. On October 12th 2009, the planet entered Cancer, the Crab, the faintest constellation of the zodiac and therefore the least easy to identify. From late October 2009 through to mid-May 2010, city-dwellers, struggling to discern Cancer under light-polluted skies, found Mars occupying the large, dark 'gap' in the night sky between Gemini and Leo; to find these two constellations from The Big Dipper (or The Plough), refer to the animation below.

From late October to early November 2009, Mars crossed the star cluster Messier 44 (M44 or NGC 2632) commonly known as Praesepe (pronounced 'pree-SEE-pee') which is visible to the naked-eye as a hazy patch of light (for more details, see below). City-dwellers detected the cluster easily with binoculars when panning the area of the sky immediately around Mars.

On November 30th 2009, Mars entered Leo, the Lion, where it remained for the next six weeks. Mid-way through its vacation, on December 21st 2009, the planet reached its Eastern stationary point, five degrees South of the star Alterf (Greek letter Lambda Leonis, mag. +4.3). The Red Planet returned to Cancer on January 10th 2010, now moving retrograde (East to West).

Mars reached opposition (i.e. its brightest for this apparition) on the night of January 29th 2010. Note that, although opposition took place on this date, Mars' closest approach to the Earth (at 0.6639 Astronomical Units or 99.33 million kms) took place two days earlier - on January 27th 2010 - because of the planet's eccentric orbit.

At opposition, a planet is positioned directly opposite the Sun in the sky (rising around sunset and setting around sunrise) and is visible throughout the night. Its highest point in the sky is reached when it crosses the observer's meridian at local midnight (due South in the Northern hemisphere, due North in the Southern hemisphere). A list of maximum altitudes and directions of the planet at several opposition dates for various latitudes is given on the current Mars page.

With an apparent magnitude of -1.3 and a maximum apparent disk diameter of 14".1 (14.1 arcseconds, where 1 arcsecond = 1/3600th of a degree), Mars at this opposition was not as bright nor as large (when seen through a telescope) as it was at its previous opposition in December 2007, when the planet reached magnitude -1.6 and had an apparent diameter of 15".8. This is because, at the 2010 opposition, the planet was further away from the Earth than it was at the 2007 opposition.

At its next opposition in 2012, the Red Planet would be even further from the Earth, appearing smaller still (13".9) and fainter (mag. -1.2). At this time, Mars would be near the point in its orbit when it was most distant from the Sun (a point called aphelion); such oppositions are often referred to as aphelic oppositions (for more details, see the Mars Oppositions page).

Date

Constellation

Apparent

Magnitude

Apparent

Diameter

(arcsecs)

View from

Earth

(0h UT)

(North up)

Distance (AU)*

Solar

Elongation

Illuminated

Phase

Central

Meridian

Longitude

(0h UT)

from Earth

from Sun

2009

 Aug 22

Tau

+1.0

5".6

View of Mars from Earth on August 22nd 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6589

1.4732

61W

89%

104

Sep 1

Gem

+1.0

5".8

View of Mars from Earth on September 1st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6032

1.4859

65W

89%

007

Sep 11

Gem

+0.9

6".1

View of Mars from Earth on September 11th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.5437

1.4989

68W

89%

270

Sep 21

Gem

+0.8

6".3

View of Mars from Earth on September 21st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4802

1.5119

72W

88%

174

Oct 1

Gem

+0.8

6".6

View of Mars from Earth on October 1st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4128

1.5250

76W

88%

078

Oct 11

Gem

+0.7

7".0

View of Mars from Earth on October 11th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.3420

1.5379

81W

88%

341

Oct 21

Cnc

+0.6

7".4

View of Mars from Earth on October 21st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.2679

1.5506

86W

88%

246

Oct 31

Cnc

+0.5

7".9

View of Mars from Earth on October 31st 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1912

1.5630

91W

88%

150

Nov 10

Cnc

+0.3

8".4

View of Mars from Earth on November 10th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1127

1.5749

97W

89%

055

Nov 20

Cnc

+0.1

9".1

View of Mars from Earth on November 20th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

1.0334

1.5864

103W

89%

320

Nov 30

Cnc

-0.0

9".8

View of Mars from Earth on November 30th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9551

1.5973

111W

90%

227

Dec 10

Leo

-0.2

10".6

View of Mars from Earth on December 10th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8797

1.6076

119W

92%

134

Dec 20

Leo

-0.5

11".6

View of Mars from Earth on December 20th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8099

1.6172

128W

93%

042

Dec 30

Leo

-0.7

12".5

View of Mars from Earth on December 30th 2009 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7494

1.6261

139W

95%

311

 2010

Jan 9

Leo

-0.9

13".3

View of Mars from Earth on January 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7022

1.6341

151W

97%

222

Jan 19

Cnc

-1.1

13".9

View of Mars from Earth on January 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4.0)

0.6726

1.6413

164W

99%

134

Jan 29

Cnc

-1.3

14".1

View of Mars from Earth at opposition on January 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.6641

1.6477

175W

100%

047

Feb 8

Cnc

-1.1

13".8

View of Mars from Earth on February 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.6780

1.6531

166E

99%

320

Feb 18

Cnc

-0.9

13".1

View of Mars from Earth on February 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7134

1.6576

153E

98%

232

Feb 28

Cnc

-0.6

12".2

View of Mars from Earth on February 28th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.7670

1.6611

142E

96%

143

Mar 10

Cnc

-0.4

11".2

View of Mars from Earth on March 10th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.8347

1.6637

131E

94%

052

Mar 20

Cnc

-0.1

10".3

View of Mars from Earth on March 20th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9126

1.6653

121E

93%

321

Mar 30

Cnc

+0.1

9".4

View of Mars from Earth on March 30th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

0.9974

1.6659

113E

91%

228

Apr 9

Cnc

+0.3

8".6

View of Mars from Earth on April 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.0862

1.6655

106E

90%

134

Apr 19

Cnc

+0.5

8".0

View of Mars from Earth on April 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.1771

1.6641

99E

90%

040

Apr 29

Cnc

+0.7

7".4

View of Mars from Earth on April 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.2684

1.6617

93E

89%

305

May 9

Cnc

+0.8

6".9

View of Mars from Earth on May 9th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.3588

1.6584

88E

89%

210

May 19

Leo

+0.9

6".5

View of Mars from Earth on May 19th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.4475

1.6540

82E

89%

114

May 29

Leo

+1.0

6".1

View of Mars from Earth on May 29th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.5335

1.6488

78E

89%

018

Jun 8

Leo

+1.1

5".8

View of Mars from Earth on June 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6163

1.6426

73E

90%

281

Jun 18

Leo

+1.2

5".5

View of Mars from Earth on June 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.6956

1.6356

69E

90%

184

Jun 28

Leo

+1.3

5".3

View of Mars from Earth on June 28th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.7708

1.6277

65E

91%

087

Jul 8

Leo

+1.4

5".1

View of Mars from Earth on July 8th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.8418

1.6190

61E

91%

350

Jul 18

Leo

+1.4

4".9

View of Mars from Earth on July 18th 2010 at 0h UT (Image from NASA's Solar System Simulator v4)

1.9083

1.6095

57E

92%

252

* 1 AU (Astronomical Unit) = 149,597,870 kms (92,955,806 statute miles)

Table of selected data relating to the brighter part of the Mars apparition of 2009-10. The data is listed at 10-day intervals, corresponding with the dates on the star map. The Central Meridian Longitude (provided for telescopic observers) is the Martian longitude which appeared at the centre of the disk when seen from the Earth at the time indicated (0h Universal Time, or 0h GMT). The data for the table was obtained from 'MegaStar', 'SkyGazer Ephemeris'  and 'Mars Previewer II' software and the Martian disk images were derived from NASA's Solar System Simulator. The Martian disks appear at the same scale as those in the Mars Opposition data table on the Mars Oppositions page.

Mars faded rapidly after opposition as its distance from Earth increased, but it remained visible for a further 10 months in the evening sky, slowly closing in on the setting Sun. Mars reached its Western stationary point in Western Cancer, 7.2 North-west of Asellus Borealis and 7.7 South-west of Pollux, on March 11th 2010. The planet left Cancer and entered Leo once more on May 12th 2010, where it stayed for a little over two months before entering Virgo on July 19th of that year.

By December 2010, Mars became lost from view in the dusk twilight. The planet's furthest distance from Earth for this apparition (2.3793 AU or 356 million kms) was reached on January 7th 2011, when its apparent diameter was a mere 3".9 across.

 

Date Range

Constellation

<----- Mid-Period ----->

Apparent Magnitude

Apparent

Diameter

(arcsecs)

Solar

Elongation

2010

Jul 19 to Sep 26

Virgo

+1.5

4".4

46E

Sep 26 to Oct 27

Libra

+1.5

4".0

30E

Oct 27 to Nov 8

Scorpius

+1.4

4".0

 24E

Nov 8 to Dec 3

 

Ophiuchus

+1.3

3".8

19E

Dec 3 to

Sagittarius

+1.2

3".8

10E

2011

 Jan 15

Table showing the position and apparent magnitude of Mars for the latter part of the 2009-10 apparition. The magnitudes, diameters and solar elongations again refer to the middle of the period in question. As the apparition drew to a close, Mars headed Southwards along the ecliptic, moving from Virgo through to Sagittarius, where the apparition had begun some 23 months previously.

Mars passed behind the Sun - at superior conjunction - on February 4th 2011. The 2011-2013 apparition began soon afterwards, which saw Mars in the constellation of Leo at its next opposition on March 3rd 2012 (for details, see the Mars 2011-13 page).

 [Terms in yellow italics are explained in greater detail in an associated article describing planetary movements in the night sky.]

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Finding Mars in the Night Sky, August 2009 to July 2010

From late August to mid-October 2009, when Mars was moving through Gemini, The Big Dipper (The Plough) could be used to locate Gemini using the method shown in the animation here.

From late October 2009 through to about mid-May 2010, when Mars was moving through Cancer, the planet was found inside a triangle formed by the stars Regulus (in Leo), Castor (in Gemini) and Procyon (in Canis Minor). Throughout this period, Mars was brighter than any of the stars contained within this triangle, so observers in both town and city spotted Mars long before Cancer itself was identified.

Finally, from late May to mid-July 2010, when Mars was moving through Leo, The Big Dipper could be used to find Leo using the method shown in the animation referred to above.

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Bright Stars, Nearby Stars and Open Star Clusters

From November 2009 to early April 2010, Mars was brighter than all of the stars shown on the star map. The four brightest stars shown are Procyon (Greek letter Alpha Canis Minoris, magnitude +0.4), Pollux (Greek letter Beta Geminorum, mag. +1.1), Regulus (Greek letter Alpha Leonis, mag. +1.3) and Castor (Greek letter Alpha Geminorum, mag. +1.6). Mars was brighter than both Regulus and Castor throughout the period, and was only exceeded in brightness by Procyon prior to November 2009 and after mid-April 2010. The planet was brighter than Pollux as it entered the star chart (late August 2009) and only became fainter than it after mid-June 2010.

Procyon, in the constellation Canis Minor (the Lesser Dog) is the eighth brightest star in the night sky and the fourth brightest Northern celestial hemisphere star. Procyon is a Greek name meaning 'before the dog', referring to the fact that it rises before the 'Dog Star', i.e. Sirius (Greek letter Alpha Canis Majoris, mag. -1.4, the brightest star in the night sky). Canis Minor contains little of interest for the binocular or telescopic observer, except for a few double stars. Procyon itself is interesting in that it has a companion white dwarf star (Procyon B), of very high density, orbiting the primary star (Procyon A) every 41 years. Procyon B is 11th magnitude and lies too close to Procyon A to be detectable in anything but professional telescopes; indeed, it was not discovered until 1896. Procyon is 11.4 light years distant (where 1 light year = 63,240 AU), meaning that it takes light 11.8 years to traverse the distance, and is one of the nearest stars to the Earth. Sirius is however closer still, at 8.6 light years and co-incidentally it also has a white dwarf companion.

Gemini's leading stars Castor and Pollux are named after the twins of Queen Leda of Sparta in ancient Greek mythology; the Romans identified them with the brothers Romulus and Remus who, according to ancient tradition, founded the city of Rome. The two stars are seperated by 4.5, providing a useful reference for measuring angular distances in the night sky. The constellation's Western half is set against the backdrop of the Milky Way, so this region contains several open star clusters (groups of young stars within our galaxy which have been formed from the same nebulous cloud) and nebulae (interstellar clouds of gas and dust). The whole constellation also features numerous double stars and multiple stars.

Castor is part of a complex star system. The main star (Castor A) has a companion (Castor B, mag. +2.9) about 4".6 (4.6 arcseconds) away from it; a small telescope will be able to split the two. Larger telescopes will reveal a third star (Castor C or YY Geminorum) of ninth magnitude, some 70" away. Not visible in amateur telescopes is an additional companion star to each of these three stars, making Castor a sextuple star system. Castor and Pollux lie at distances of 52 light years and 34 light years from Earth, respectively.

During the final days of August and into early September 2009, Mars passed close to three bright stars and one open star cluster, all situated towards the 'foot' of the Western Twin.

Gemini's Westernmost bright star is 1 Geminorum (mag. +4.1); Mars passed 0.3 North of this star on August 27th 2009. Sir William Herschel discovered Uranus in the vicinity of this star in March 1781; the blue-green planet was then situated just across the border in Taurus.

Photograph of Cancer and the Northern section of Hydra, showing the path of the ecliptic (click for full-size picture)

Cancer and Northern Hydra  A photograph showing the region of the night sky which Mars passed through during the 2009-10 observing season. The asterism forming the head of the Water Snake is somewhat more obvious than Cancer itself (move your pointer over the image - or click here - to identify the constellations and click on the image for a full-size picture).

A short distance North-east of 1 Geminorum is the open star cluster M35 or NGC 2168. It can be glimpsed with the naked-eye on a dark, clear night as a small, misty patch of light. Mars passed 0.8 South of the cluster on August 29th 2009. The cluster has an apparent diameter about the size of the Full Moon and it contains over 400 stars (!) It lies at a distance of about 2,800 light years from the Earth. Binoculars show a bright, elliptical glow with several stars, the cluster appearing somewhat 'doughnut-shaped' since there are considerably fewer stars at its centre. Small telescopes fitted with wide-field (low magnification) eyepieces show curving chains of stars from 8th to 12th magnitude. M35 is one of the more spectacular open star clusters in the night sky and astronomy authors have variously described its appearance as 'rich', 'beautiful', 'outstanding' and 'marvelous'!

The star Eta Geminorum (Greek letter Eta Gem, mag. +3.1v), also known as Propus or Tejat Prior (meaning 'forward foot') is both a double star and a variable star. It has a close companion star of 8th magnitude which orbits the primary star once every 500 years; medium or large telescopes are required to resolve the pair. Tejat Prior is a red giant which fluctuates in brightness between mags. +3.1 and +3.9 over the course of about 230 days. Mars passed 1.1 North of Tejat Prior on August 31st 2009. Three days later (September 3rd) the planet passed 1.0 North of Mu Geminorum (Greek letter Mu Gem, mag. +3.2v), or Tejat Posterior ('latter foot'). This is also a double star, having a ninth-magnitude companion positioned some 2' (2 arcminutes, where 1 arcminute = 1/60th of a degree) to the South-east of the primary, visible in small telescopes. The secondary star itself has a tenth-magnitude companion which requires larger telescopes to resolve.

On September 25th 2009, the Red Planet passed 0.8 North of another double star, Wasat (Greek letter Delta Geminorum, mag. +3.5), a name which is Arabic for 'middle'. The primary star is creamy-white and its magnitude +8.2 companion is orange. This pair should be easy to split, however the great brightness difference between the two stars makes them difficult to split in smaller telescopes. Astronomer Clyde Tombaugh discovered Pluto near Wasat in February 1930, while he was examining photographic plates of the region which had been taken between January 23rd and 29th of that year.

Cancer, the Crab, is the faintest constellation of the zodiac and therefore the most difficult to see, particularly from urban and suburban locations, where the limiting magnitude (the faintest stars visible at the observer's zenith) may only be around +4.0. Cancer's five brightest stars form a shape reminiscent of the Greek letter lambda in lower case (Greek letter Lambda). The brightest star (mag. +3.5) has been incorrectly assigned the name Beta Cancri (Greek letter Beta Cnc) where it should technically have been classed as Alpha (Greek letter Alpha). The actual star carrying the designation Greek letter Alpha Cancri is named Acubens (meaning 'claws', mag. +4.3). It is a double star with an 11th magnitude companion; a small telescope will resolve them.

The star Iota Cancri (Greek letter Iota Cnc, mag. +4.0), at the Northern end of the Crab, is a double star with a magnitude +6.5 companion. The stars are seperated by a sizeable 30" (30 arcseconds) allowing the pair to be resolvable in 10x50 binoculars. Telescopes show the stars to be a pretty combination of gold and pale-blue.

Cancer contains two interesting open star clustersM44 (NGC 2632) is known as Praesepe or 'The Beehive Cluster' because of its binocular resemblance to a cloud of swarming bees. It is visible to the naked eye as a hazy patch of light at the constellation's centre but is much better seen through binoculars and telescopes. It lies at a distance of about 520 light years and is thought to be about 650 million years old. Binoculars show around 50 stars contained in a field of view roughly 80' (80 arcminutes) across. Small to medium-sized telescopes reveal about 75 stars visible down to about magnitude 12, whilst large telescopes show around 300 stars down to 17th magnitude. Because of Praesepe's large area (it is 95' across) telescopes need to be fitted with wide-field eyepieces in order to appreciate the full splendor of this cluster.

Praesepe is positioned a short distance North of the ecliptic (the apparent path of the Sun, which the Moon and planets follow very closely), so planets regularly pass across it in rather spectacular fashion. In 2009, Mars crossed the cluster between October 31st and November 2nd - a pretty sight when seen through binoculars.

 

The path of Mars through M44 in late October/early November 2009

M67 open star cluster in Cancer

Open Star Clusters in Cancer  Two examples of open star clusters which can easily be seen in binoculars: (Left) M44 (NGC 2632, commonly known as Praesepe or the Beehive Cluster) and (Right) M67 (NGC 2682) in the Southern region of the constellation. Mars passed through (in front of) M44 in late October/early November 2009 (move your pointer over the image - or click on it - to see the track of the planet, marked at 0h UT on each date). Mars later passed 1.2 to the North of the cluster, while moving retrograde, in mid-April 2010. Stars in the pictures are visible down to about magnitude +8.3. North is up and East is to the left in both pictures (Photos Copyright Martin J Powell, 2005-6)

The following day (November 3rd 2009), Mars passed mid-way between the stars Asellus Borealis (Greek letter Gamma Cancri, mag. +4.7) and Asellus Australis (Greek letter Delta Cancri, mag. +3.9). Bizarrely, the names mean 'northern donkey' and 'southern donkey' respectively. This probably relates to the fact that M44 is sometimes referred to as 'The Manger' in reference to the Nativity story; in this case the donkeys are considered to be feeding at the Manger. Mars again passed between these two stars on April 19th 2010, although on this occasion it was positioned closer to Asellus Borealis, being 0.8 to the South of it.

M67 (NGC 2682) is located 1.7 to the West of Acubens. It is smaller and denser than M44 and is just beyond naked-eye visibility. There are over 300 stars in the cluster, which lies about 2,600 light years away. Binoculars show it as a small, hazy patch; small telescopes reveal about 20 stars down to 11th magnitude and medium-sized telescopes show around 50 stars down to 12th magnitude. With an estimated age of 5 billion years, this is one of the oldest known open star clusters, containing several red giant stars nearing the end of their lives.

Leo is perhaps the most recognisable of the zodiac constellations, and one of the few which bears a resemblance to the animal it is supposed to represent - a crouching Lion. The Lion's head and 'mane' are an asterism of its six Westernmost stars commonly called the Sickle of Leo, which is shaped like a backward question-mark [A backwards question-mark!] At the base of the question-mark is Leo's brightest star, Regulus. It is also the closest bright star to the ecliptic, lying about 0.5 degrees away from it. One consequence of this is that the star is regularly passed by the Moon and planets - indeed, Mars passed 0.9 North of it on June 6th 2010. The fact that the name Regulus and the word 'Regal' are similar is no coincidence; Regulus is Latin for 'Little King', reflecting an ancient belief that it controlled the affairs of the heavens. It was given the name in the sixteenth century by the famous Polish astronomer Nicolaus Copernicus.

Approximately mid-way between the 'upper hind leg' stars Coxa (Greek letter Theta Leonis, mag. +3.9) and Greek letter Iota Leonis are a pair of galaxies about 37 million light years away. M65 (NGC 3623, mag. +9.5) and M66 (NGC 3627, mag. +8.8) are positioned 20' (0.3) apart and are among the brightest of many dozens of galaxies which exist in the constellation of LeoM65 and M66 appear relatively bright and elliptical through small telescopes, orientated in a North-South direction. They are just discernible through binoculars in dark, moonless skies as faint, circular hazy patches of light.

Finally, on July 12th 2010, Mars passed 1.0 South of the star Sigma Leonis (Greek letter Sigma Leo, mag. +4.0) at the 'foot' of Leo's hind leg. One week later, the planet moved from Leo into Virgo and out of the star chart coverage (the path of Mars from this date is continued on the Venus 2010 page).

Other constellations on the chart contain objects of interest which observers may wish to track down, and these will now be discussed briefly.

The Rosette Nebula (NGC 2237) imaged by John Lanoue

The Rosette Nebula (NGC 2237) is a diffuse nebula situated in the constellation of Monoceros. The star cluster NGC 2244 is at its centre (Image: Wikimedia Commons, with permission of John Lanoue)

The constellation Monoceros, the Unicorn, is positioned between Procyon and Sirius. The fact that it is outshone by these two luminaries somewhat detracts from the fact that it contains a number of interesting star clusters and nebulae. Perhaps the most interesting of these is the Rosette Nebula (NGC 2237), an emission nebula which glows by emitting light from the radiation of the young, hot stars contained within it. The Rosette is about 4,700 light years distant and appears much like a beautiful pink carnation in long-exposure photographs. Alas, it is too faint to be seen in binoculars and small telescopes; medium and large telescopes are only likely to reveal the nebula's brightest regions when seen under very dark skies. More obvious to binocular and small telescope observers will be the star cluster at the nebula's centre (NGC 2244) comprising numerous stars of sixth magnitude and fainter.

In the Southern part of Monoceros is the open star cluster M50 (NGC 2323), about 2,600 light years distant. Its brightest stars can be seen in binoculars but a telescope is needed to resolve its 150 or so stars.

The Christmas Tree (NGC 2264) is an open star cluster with an associated nebulosity known as the Cone Nebula. The nebula is too faint to be seen in amateur telescopes, but the cluster's leading star, fifth-magnitude S Monocerotis (or 15 Mon), situated at the Northern end (base) of the 'Tree', is easily seen in binoculars, along with about 20 other stars down to about ninth magnitude. The 'Christmas Tree' appears inverted to Northern hemisphere observers and upright to Southern hemisphere observers. Appropriately, the Christmas Tree cluster crosses the observer's meridian (due South in the Northern hemisphere, due North in the Southern hemisphere) at local midnight around Christmas time.

Leo Minor (the Little Lion or Lion Cub), situated between Leo itself and Ursa Major, is fainter even than Cancer. It contains no stars brighter than magnitude +3.8 and there are no deep-sky objects (star clusters, nebulae and galaxies) to view in moderate-sized telescopes or binoculars. Because of a 19th century error when assigning star labels, this constellation has no star named Alpha (Greek letter Alpha) Leonis Minoris, although this should technically have been assigned to its brightest star, 46 Leonis Minoris.

Lynx, like Leo Minor, is a relatively recent constellation, having been introduced in the 17th-century by the Polish astronomer Johannes Hevelius. It bears no resemblance to a lynx and was in fact so-named because, as Hevelius put it, "only the lynx-eyed would be able to see it"! Lynx contains numerous double stars and multiple stars of interest to the amateur observer.

Hydra, the Water Snake, is the largest constellation in the sky, extending across 95 of celestial longitude; only its Northern section is included in the star chart. Hydra snakes its way between no less than ten constellations, starting just South of Cancer and ending just to the South of Libra. Hydra's brightest stars are all found in its Northern half, at the top of which is an asterism of six stars which form the distinctive shape of the Water Snake's head.

Close to Hydra's Western border with Monoceros is the open star cluster M48 (NGC 2548). It is about 2,000 light years away and comprises some 80 stars, covering an area about the same apparent size as the Full Moon. Under dark skies, the cluster can just be seen with the naked-eye as a hazy spot and around 50 stars of the group can be resolved in binoculars. Telescopes reveal several yellowish stars along with mostly white ones, some of them double.

 

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Moon near Mars Dates, September 2009 to December 2010

The Moon is easy to find, and on one or two days in each month, it passes Mars in the sky. The following tables list the dates on which the Moon passed near the planet between September 2009 and December 2010:

Date Range

(World)

Conjunction (Geocentric)

Solar Elong.

Moon Phase

Date & Time

Sep. & Dir.

2009

Sep 13/14

Sep 13, 15:59 UT

1.1 S

69W

Waning Crescent

Oct 11/12

Oct 12, 01:27 UT

1.1 N

81W

Waning Crescent

Nov 8/9

Nov 9, 06:00 UT

3.5 N

96W

Last Quarter

Dec 6/7

Dec 7, 02:45 UT

5.5 N

116W

Waning Gibbous

Moon near Mars dates for the period from August 2009 to December 2010. The Date Range shows the range of dates worldwide (allowing for Time Zone differences across East and West hemispheres). Note that the Date, Time and Separation of conjunction (i.e. when the two bodies were at the same Right Ascension) are measured from the Earth's centre (geocentric) and not from the Earth's surface (times are Universal Time [UT], equivalent to GMT). The Sep. & Dir. column gives the angular distance (separation) and direction of the planet relative to the Moon, e.g. on April 22nd 2010 at 09:27 UT, Mars was positioned 4.6 North of the Moon's centre. The Moon Phase shows whether the Moon was waxing (between New Moon and Full Moon), waning (between Full Moon and New Moon), at crescent phase (less than half of the lunar disk illuminated) or gibbous phase (more than half but less than fully illuminated).

Date Range

(World)

Conjunction (Geocentric)

Solar Elong.

Moon Phase

Date & Time

Sep. & Dir.

2010

Jan 2/3

Jan 3, 11:31 UT

6.8 N

114W

Waning Gibbous

Jan 29/30

Jan 30, 08:06 UT

6.6 N

175E

Full

Feb 25/26

Feb 26, 05:08 UT

5.3 N

143E

Waxing Gibbous

Mar 25/26

Mar 25, 13:58 UT

4.5 N

117E

Waxing Gibbous

Apr 21/22

Apr 22, 09:27 UT

4.6 N

97E

Waxing Gibbous

May 19/20

May 20, 11:48 UT

5.2 N

82E

First Quarter

Jun 17/18

Jun 17, 18:39 UT

5.9 N

69E

Waxing Crescent

Jul 15/16

Jul 16, 04:44 UT

6.2 N

58E

Waxing Crescent

Aug 13/14

Aug 13, 17:22 UT

5.9 N

48E

Waxing Crescent

Sep 10/11

Sep 11, 08:22 UT

5.0 N

39E

Waxing Crescent

Oct 9/10

Oct 10, 01:51 UT

3.5 N

30E

Waxing Crescent

Nov 7/8

Nov 7, 22:11 UT

1.6 N

22E

Waxing Crescent

Dec 6/7

Dec 6, 21:45 UT

0.5 N

14E

Waxing Crescent

Lovers' Conjunction

On August 13th 2010, during the closing months of Mars' 2009-10 apparition, an interesting grouping of the Moon and planets took place in the evening sky. This is the writer's simulation of how the event might have appeared from the island of Tenerife in the Canary islands (Islas Canarias) around 10 pm Local Time (22:00 Western European Summer Time or 21:00 UT), some two hours after local sunset.

Looking West, the three-day-old Moon, Venus (mag. -4.3) and Saturn (mag. +0.9) formed a line spanning 13.6 across which appeared almost parallel with the local horizon. Mars (mag. +1.5) was positioned 2.7 above (Northeast) of the trio, having just passed conjunction with the Moon (see table above). The group were situated in central Virgo at the time, a short distance to the South of the star Porrima (mag. +3.6). Mercury (mag. +0.6) was also visible for a short while earlier that evening, low down in the West some 16 to the West of Saturn (below and to the right of Saturn in the picture).

The Moon, Venus and Saturn sank below the horizon, within a five minute period, around 23:00 Local Time. Mars, now much dimmer and distant than in previous months, set about nine minutes later.

Seen from the rest of the world, the angle of the Moon and the planets in relation to an observer's horizon varied according to the observer's latitude (Tenerife is situated at 28 20' North). The position of the Moon itself in relation to the planets also varied depending upon the local time at which the grouping was observed.

Move your pointing device over the image to identify the stars and planets and click on the image for a full-sized picture.

The picture was based on a photograph at Wikipedia.

Lovers' Conjunction, Tenerife

The Moon moves relatively quickly against the background stars in an Eastward direction, at about its own angular width (0.5) each hour (about 12.2 per day). Because it is relatively close to the Earth, an effect called parallax causes it to appear in a slightly different position (against the background stars) when seen from any two locations on the globe at any given instant; the further apart the locations, the greater the Moon's apparent displacement against the background stars. Therefore, for any given date and time listed in the table, the Moon will have appeared closer to Mars when seen from some locations than others. For this reason, the dates shown in the table should be used only for general guidance.

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The Naked-eye appearance of Mars

Naked Eye Planet Index

Planetary Movements through the Zodiac

Mercury

Venus

Mars

Jupiter

Saturn

Uranus

Neptune

Pluto


Credits


Copyright  Martin J Powell  June 2009


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