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A Midsummer Night’s Scene

William Shakespeare may have viewed the world as a stage, but the real show is often in the heavens above. The night of July 10th was one of those picture-perfect evenings; a cold front had passed through earlier in the day replacing the oppressive humidity with cool, dry air. In a scene worthy of Shakespeare, Saturn rendezvoused with Mars in the western sky as the mythological couple pursued Regulus into the deepening twilight. Further south, an 8-day old moon (Luna) illuminated the night with her pale, cold light while in the southeast; a radiant Jupiter was rising above the treetops. The celestial thespians were joined by the portentous Scorpius in the south, Ursa Major prowling in the north and the stars of the summer triangle high overhead. It was a show not to be missed.

No Blueberries for Mars

Phoenix mission scientists were pleasantly surprised when they discovered the soil at the landing site in the northern polar region of Mars was similar to soil found in the dry valleys of Antarctica. The instruments on the Phoenix lander found a variety of minerals and salts in the soil covering the icy surface. They also determined that the soil chemistry was alkaline, with a pH of between eight and nine; good for growing asparagus and turnips, but not blueberries and strawberries, which like an acidic environment.

Nature’s Optics

When we usually discuss optics in this forum, it is in reference to the lens and mirrors you would find in various types of telescopes. However, you don’t need a man made device to appreciate the basic principals of how different materials can manipulate light.

Water drops can act as miniature convex lens, capturing tiny, inverted images. The photo on the left shows two water droplets hanging from a small branch. Behind the branch are some flowers and a rock wall. The droplets are held together by water tension and can continue to grow as more moisture is collected until gravity overcomes the surface tension and the drop falls to the ground. While the background is out of focus, the image within the water drop is much clearer. The image on the right has been inverted and shows a scene reminiscent of a camera with a fisheye lens. The image in the water droplet includes a nearby tree and its canopy of branches above, the field of grass beyond the rock wall and the bright sky overhead.

Largest Crater in the Solar System

Even the most casual observer of Mars will notice that the northern hemisphere appears relatively smooth and devoid of the dark features that crisscross the southern hemisphere. More than a just a difference in appearance, large areas of the northern hemisphere are 2½ to 5 miles lower than the planet’s crust in the southern hemisphere.

Data collected by NASA's Mars Reconnaissance Orbiter and Mars Global Surveyor on the elevations and gravity of the northern and southern hemispheres suggests that the Borealis basin (in the northern hemisphere) may actually be a very large impact crater; the largest in the solar system.

The Borealis basin covers almost 40 percent of the surface of Mars. At 5,300 miles across, it is four times wider than the next-largest known impact basin in the solar system; the Hellas basin in the southern hemisphere of Mars. It is estimated that the object that would have created the basin would have been about 1,200 miles across; larger than Pluto. The basin’s outline has been partially obscured by the giant shield volcanoes that formed along one edge. The true nature of the basin wasn’t evident until the detailed mapping by the orbiting spacecraft.

The Easter Bunny Gets a New Name

The Kuiper belt object designated 2005 FY9, discovered by a team led by Mike Brown, has been formally designated “Makemake” by the International Astronomical Union’s Working Group on Planetary Nomenclature on July 11, 2008. Makemake now joins Pluto and Eris as both a dwarf planet and a plutoid.

Makemake (pronounced MAH-kay MAH-kay) is one of the largest objects in the outer Solar System. It is only slightly smaller and dimmer than Pluto. Its orbit is just beyond that of Pluto; however it is much more tilted to the plane of the solar system than Pluto’s.

Mike Brown’s discovery team originally used the code name “Easterbunny” for the object before the discovery was made public, because the discovery was made shortly after Easter. Makemake is the creator of humanity and the god of fertility in the mythology of the South Pacific island of Easter Island. He was the chief god of the Tangata manu bird-man cult. His material symbol was a man with a bird's head.

Wooden effigy of a bird man
(Peabody Museum, Harvard University)

Trivia

Can you guess when these photos were taken? July 4th would be the obvious answer; however, if you are a frequent reader of this publication, you might suspect that there is more to the answer (and you would be correct). It just so happened this year that the Earth reached its furthest point in its orbit around the Sun on July 4th. The Earth’s orbit is not a perfect circle, but an ellipse. The Earth is actually closer to the Sun in January and furthest away in July. However, since the difference in orbital distance is very small for Earth, the effect isn’t really noticeable (the Sun on July 4th only appeared 1.7% smaller than usual). Planets like Mercury and Pluto have much more elongated orbits. Astronomers refer to this distant point in a planet’s orbit as “Aphelion,” a word derived from the Greek words "apo" (away from) and "helios" (Sun).

August Solar Eclipse

The moon slipped in front of the Sun on August 1st, providing the residents of northern Canada, northern Greenland, the Arctic, central Russia, Mongolia and China with a rare treat. The image on the right was taken during “totality;” when the moon fully covers the solar disk. At this time the otherwise faint solar corona (the Sun’s outer atmosphere) shines brightly against the darkened sky.

If you missed it, there will be another solar eclipse next year. On July 22, 2009 the moon’s shadow will race across India, China, several small Japanese islands (including Iwo Jima) and the South Pacific Ocean. Residents of China's largest city Shanghai (with a population of almost 19 million) will experience a totality lasting 5 minutes. Visit NASA’s solar eclipse page (http://eclipse.gsfc.nasa.gov/solar.html) for more information.

Jupiter

Jupiter reached Opposition on July 9th and, while setting earlier, is still visible throughout most of the night. As one of the brightest star-like objects in the night sky, Jupiter can be found in the constellation Sagittarius.

One of the more interesting and easiest events to observe through a telescope is the projection of a shadow from one of Jupiter’s moons on the Jovian disk as the moon passes in front of (or transits) the planet. The photo on the right shows the shadow of Ganymede on the Jovian disk. On nights of good visibility the following events should be visible through a moderately-sized telescope (between 9 pm and midnight).

 

Date	Moon	Transit begins	Transit Ends
1st	Europa	10:49 pm	1:34 am (2nd)
7th	Io	8:12 pm	10:28 pm
	Ganymede	4:40 pm	8:38 pm
14th	Io	10:07 pm	0:23 am (15th)
16th	Ganymede	10:41 pm	2:00 am (17th)
26th	Europa	7:55 pm	10:41 pm

Transit of Jupiter’s Red Spot

The Red Spot is a large cyclone in the upper Jovian atmosphere. The rapid rotation of this gas giant (10 hours) may be responsible for the longevity of this storm. The Red Spot will cross the center line of the planetary disk on the following evenings during the hours 8 pm to midnight local time (EDT):

Date	Transit Time	Date	Transit Time
2nd	11:58 pm	17th	9:25 pm
5th	9:28 pm	19th	11:03 pm
7th	11:07 pm	22nd	8:34 pm
10th	10:16 pm	24th	10:13 pm
12th	10:16 pm	26th	11:51 pm
14th	11:54 pm	29th	9:22 pm

September Nights

Enjoy the jewels of the summer Milky Way while the nights are still warm and the skies are clear. From Cygnus to Sagittarius, follow the star clouds and dust lanes that comprise the inner arms of our spiral galaxy. In the south after sunset, the stars in the constellation Sagittarius form an asterism, or pattern, of a teapot. The spout of the teapot points the way to the center of the Milky Way galaxy with its resident black hole. Check out the July/August calendar for more details.

Autumnal Equinox

The Sun crosses the celestial equator at 11:44 am EDT on September 22nd, marking the beginning of the fall season in the northern hemisphere.

Sun Sunrise Sunset
September 1st (EDT) 06:20 19:26
September 15th 06:34 19:02
September 30th 06:50 18:36

 

Aurora and the Equinoxes:

Geomagnetic storms that are responsible for auroras happen more often during the months around the equinox (March and September). Check your evening sky or log onto www.spaceweather.com for the latest on solar activity.

Harvest Moon

The full moon that occurs closest to the Autumnal Equinox is known as the Harvest Moon. This year the full moon occurs on the night of September 15th. The Harvest Moon traditionally appears around the time when farmers in the northern hemisphere are working long days to bring in their crops. The full moon provides a bit more light, longer into the evening. However, what is really special at this time of the year is the appearance of the moon in the days just before and after it reaches its full phase.

Throughout the year the Moon rises, on average, 50 minutes later each day. In September (and October), on the days around the full moon, this decreases to less than 30 minutes. On the graph (above), the difference in the time of moonrise on two days preceding and following the full moon are plotted. In late September, the difference is as little as 22 minutes (from one night to the next). The effect is that an almost fully illuminated moon is in the evening sky earlier each evening, benefiting those farmers still out in the field (and children playing after school).

For example, the Moon rises at 5:58 p.m. on September 15th, the night of the Full Moon. The next two nights the Moon rises 24 and 27 minutes later, respectively. This means that on the 17th, (two days after full) a bright moon is back in the sky less than an hour after sunset.

Present and Future Pole Stars

Vega, the fifth brightest star and located in the constellation Lyra, is placed high in the evening sky during September. Vega is also destined to become the Pole Star in 12,000 years. Precession, or the change in the direction of the rotational axis of the Earth over time, is best exemplified in a comparison of the position of Vega to that of Polaris (the current Pole Star).
Astronomical and Historical Events

1st Photo Op: Crescent moon joins Mercury, Venus and Mars low in the west-southwest sky shortly after sunset
1st Asteroid 951 Gaspra closest approach to Earth (0.916 AU) – Gaspra was visited by the Galileo spacecraft in October 1991 on its way to Jupiter
2nd Distant flyby of Saturn’s moon Janus by the Cassini spacecraft
3rd Distant flyby of Saturn’s moon Methone by the Cassini spacecraft
3rd History: the Viking 2 spacecraft lands on the Martian surface (1976)
5th Rosetta spacecraft flyby of the Asteroid 2867 Steins on its way to Comet 67 P/Churyumov-Gerasimenko
5th Asteroid 43 Ariadne at Opposition (9.8 Magnitude)
5th History: launch of Voyager 1 to the planets Jupiter and Saturn (1977)
7th Shadows of Jupiter’s moons Io and Ganymede visible transiting the disk of Jupiter between 8:12 pm and 8:38 pm. Ganymede’s shadow transit will be ending while Io’s is beginning.
7th Moon at apogee (furthest distance from the Earth)
8th History: 1st Star Trek episode airs on television (1966)
9th History: launch of Conestoga I, 1st private rocket (1982)
9th History: discovery of Jupiter’s moon Amalthea by Edward Barnard (1892)
9th History: launch of Soviet spacecraft Venera 11 (Venus lander) to the planet Venus (1978)
10th Launch of Russian Progress supply ship to the International Space Station
10th Distant flyby of Saturn’s moon Epimetheus by the Cassini spacecraft
11th Mercury at greatest eastern elongation (27 degrees); angle between Sun and planet as viewed from Earth
11th History: Mars Global Surveyor enters orbit around Mars (1997)
12th Uranus at Opposition (rising opposite the setting Sun in the evening sky)
12th Asteroid 2309 Mr. Spock closest approach to Earth (1.942 AU)
12th History: launch of the Soviet spacecraft Luna 2, 1st to impact surface of the Moon (1959)
12th History: launch of Gemini XI with astronauts Charles Conrad and Richard Gordon (1966)
13th Second Saturday Stars – Open House at the McCarthy Observatory
14th History: launch of Soviet spacecraft Venera 12 (Venus lander) to the planet Venus (1978)
14th History: John Dobson born, father of the dobsonian telescope (1915)
15th Full Moon (Full Harvest Moon)
17th Distant flyby of Saturn’s moons Mimas and Calypso by the Cassini spacecraft
19th Moon occults stars in the Pleiades star cluster
19th History: NASA unveiled plans to return humans to the moon (2005)
19th History: 1st launch of the Wernher von Braun-designed Jupiter C rocket from Cape Canaveral (1956)
19th History: discovery of Saturn’s moon Hyperion by William and George Bond and William Lassell (1848)
20th Moon at perigee (closest distance to Earth)
21st History: Soviet spacecraft Zond 5 returns after circumnavigating the moon (1968)
21st History: Galileo spacecraft impacts Jupiter after completion of mission (2003)
21st History: flyby of the planet Mercury by the spacecraft Mariner 10 (1974)
22nd Last Quarter Moon

22nd Autumnal Equinox, 11:44 am EDT
22nd History: flyby of the 5 mile long potato-shaped comet Borrelly by Deep Space 1 (2001)
23rd History: Johann Galle discovers the planet Neptune (1846)
24th History: John Young born (1930), 1st person to fly in space six times, including Gemini 3 (1965), Gemini 10 (1966), Apollo 10 (1969), Apollo 16 (1972), STS-1, the first flight of the Space Shuttle (1981), and STS-9 (1983)
24th History: Soviet spacecraft Luna 16 returns 101 grams of lunar soil to Earth (1970)
26th Annual Connecticut Star Party, Ashford, CT, http://www.asnh.org
26th History: Cosmonauts V. Titov and Strekalov escape moments before Soyuz T-10-1 explodes on the pad (1983)
27th History: launch (2007) of Dawn spacecraft to Vesta (2011) and Ceres (2015)
27th History: launch of SMART-1, the first European lunar probe (2003)
28th History: discovery of Jupiter’s moon Ananke by Seth Nicholson (1951)
28th History: launch of Alouette, Canada's 1st satellite (1962)
29th New Moon
30th History: all instruments deployed on moon by the Apollo missions are shut off (1977)
30th History: discovery of Jupiter’s moon Themisto by Charles Kowal (1975)

 

 

References on Distances

 

·        the apparent width of the moon (and Sun) is approximately one-half a degree (½°), the width of your little finger at arm’s length; three fingers is approximately five degrees (5°)

·        1 astronomical unit (AU) is the distance from the Sun to the Earth or approximately 93 million miles

 

International Space Station/Space Shuttle/Iridium Satellites

 

Visit www.heavens-above.com for the times of visibility and detailed star charts for viewing the International Space Station, the Space Shuttle and the bright flares from Iridium satellites.

 

Solar Activity

 

For the latest on what’s happening on the Sun and the current forecast for flares and aurora, check out www.spaceweather.com.

 

 

 

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