Jupiter. Image credit: Wes Higgins. Click to enlarge.
Greetings, fellow SkyWatchers! This week is all about Jupiter. While these sky guidelines were written before the appearance of the “Great Red Spot, Jr.” – that doesn’t mean the new storm can’t be spotted with an intermediate sized telescope. Be on the lookout for it to begin rotating inward about an hour after the GRS reaches meridian. Your best views will be achieved when Jr. also reaches meridian.
In the meantime, enjoy lunar features and meteor showers this week! It’s time to turn an eye towards the sky, because….
Here’s what’s up!
Monday, June 5 – Tonight let’s journey to the lunar surface and look at an area just south of crater Eratosthenes known as Sinus Aestuum. Its very smooth floor is curiously riddled to the north and east by dark stains. At one time Sinus Aestuum may have been completely submerged in lava. Later the molten rock sank to the Moon’s interior before it could do much more than melt away outer layers and older surface features.
Let’s continue to follow Jupiter. One thing you’ll notice is this gas giant doesn’t stand still. Even 10 minutes of observation reveals a definite drift of features across its globe. This wouldn’t be obvious if the entire planet was seen just as a series of light and dark bands running parallel to one another. There must be features on the planet that give observers reason to describe it as presenting “a wealth of detail.”
Although the Great Red Spot (GRS) has not been quite so red over the last few decades, it still remains “Great” in size. Almost three Earths could fit inside its length and two along its width! This vast anticyclone of upper atmospheric activity resides along the southern frontier of the South Equatorial Belt (SEB) but is largely embedded within it. Careful observation at higher magnifications shows that the GRS precedes a vast system of turbulence trailing it across the globe.
Since Jupiter’s day is two-fifths the length of our own, observers will be amazed to see the GRS come and go as the planet alternately presents its various faces. But, the GRS is not the only such spot in Jupiter’s turbulent cloud tops. Often great dark masses of far less longevity can be seen to come and go – particularly along, and embedded within, Jupiter’s NEB. Along with such dark “barge” formations, various semi-persistent white spots – or ovals – can also be detected. Many of these are seen south of the SEB and some can be detected in the planet’s polar region through large aperture scopes.
If you are out late, be sure to keep watch after the Moon sets for the Scorpiid meteor shower. Its radiant is near the constellation of Ophiuchus, and the average fall rate is about 20 per hour – with some fireballs!
Tuesday, June 6 – This evening on the lunar surface, look along the south shore of Mare Nubium. The thin, light ring you encounter will be crater Pitatus. Further south you will discover two mountain-walled plains whose exposed floors will show bright western and dark eastern walls. These twins are Wurzelbauer to the west and Gauricus to the east.
Wouldn’t it be nice if a telescope could actually “zoom” you towards anything as though you actually traveled that far? At 200x, Jupiter would hang suspended in space as though it were a little more than 4 million kilometers away. At this distance, the human eye could easily be overwhelmed with the many fine features visible in Jupiter’s dynamic cloud tops – especially when you consider that the planet would appear almost 5 times larger than the disk of the full moon!
Unfortunately, telescopes don’t quite work that way. The Earth’s atmosphere rules everything – even aperture – when it comes to what you can see in the night time sky. So observe every night possible and eventually you will get that “once in a lifetime” view of Jupiter!
Wednesday, June 7 – For late night or early morning SkyWatchers, be alert for the peak of the June Arietid meteor shower during the early morning hours. The radiant is in the constellation Aries and the fall rate is about 30 per hour. Most are slow moving with some fireballs.
Begin tonight by looking for bright Spica very close to the Moon. It will be so close that it will be occulted for some observers! Be sure to check with IOTA for more details.
Tonight’s lunar feature can be spotted in binoculars, but requires a telescope for detailed study. The Riphaeus Mountains can be found southwest of Copernicus. Highlighted by the bright ring of Euclides, the Montes Riphaeus show a variety of isolated hills and sharp peaks which may have been the original crater walls of Mare Cognitum before lava flow filled its floor. Northeast of the range is another smooth floored area on the border of Oceanus Procellarum. It is here that Surveyor 3 landed on April 19, 1967. After bouncing three times, the probe came to rest on a smooth slope in a sub-telescopic crater. As its on-board television monitors watched, Surveyor 3 deployed a “first of its kind” miniature shovel and dug to a depth of 18 inches. The view of sub-soil material and its clean-cut lines allowed scientists to conclude that the loose lunar soil could compact. Watching Surveyor 3 pound its shovel against the surface, the resulting tiny “dents” answered the crucial question. The surface of a mare would support the landing of a spacecraft and exploration by astronauts.
With Jupiter and the Moon so close tonight, why not try some comparison views? Observe Jupiter’s details through the telescope and compare what you see visually with the Moon. It gives you new respect for the wonders of lunar observation doesn’t it?
Thursday, June 8, 2006 – Born on this date in 1625 was the most notable observer after Galileo – Giovanni Cassini. Many of Cassini’s discoveries are easily reproduced by amateurs today. He was the first to see belts and spots on Jupiter – allowing him to accurately determine the planet’s rapid rotation. Cassini saw features on Mars clearly enough that he could determine its more Earth-like rotation as well. His observations of Saturn led to the discovery of its four brightest satellites. Cassini’s accurate records of Galilean transits across Jupiter allowed him to note discrepancies based on variations in the planet’s distance from Earth. In fact, Cassini came to think light might travel at a fixed speed! Astronomers particularly remember Cassini for his namesake division in Saturn’s ring system. Do you suppose we should name a spacecraft after him? And if so, where should we send it?
The three planets Cassini is most widely noted for observing are still visible in the evening sky. Look southwest for a rapidly setting Mars and Saturn, while Jupiter stands high the south at skydark.
Tonight’s lunar feature will be bright Aristarchus. Located on the terminator north of Kepler, this dazzling feature can sometimes be seen unaided and is easily noted in binoculars. For telescopic viewers, Aristarchus offers a splendid challenge – look for a thin, bright thread curling away from it. Named Schroter’s Valley, it is a sinuous rille and largest of its kind. It may have once been a lava tube, similar to our own terrestrial volcanic features.
Friday, June 9 – Today is the birthday of Johann Gottfried Galle. Born in Germany in 1812, Galle, along with d’Arrest, shared the distinction of discovering Neptune. This was based on calculations by Le Verrier predicting its expected position. Galle was Encke’s assistant at the Wilhelm Foerster Observatory in Berlin and became the first to see the faint “dusky ring” (Ring C) of Saturn. Galle was also one of the few astronomers ever to have seen Halley’s Comet twice. He died two months after the comet passed perihelion in 1910, at a ripe old age of 98.
Want to practice some astronomy during the day? Then grab an FM radio and enjoy the “static” as we enter a cometary debris trail and some of the strongest daytime radio meteor showers of the year. To listen to the action, all you need is an external antenna. Tune the receiver to the lowest frequency not producing a clear signal. Each time a meteor passes through our atmosphere, it leaves an ion trail that bounces back distant radio signals to you – even in a stationary car! Listen to the static for a quick rise in volume or a snatch of a distant station that lasts a second or two then fades back to static.
Tonight’s highlighted lunar feature can be seen in binoculars but is best viewed telescopically. Located in the southwest quadrant on the terminator just south of Shickard, crater Wargentin is most unique. Once upon a time, it was a very normal crater and remained that way for hundreds of millions of years – then it happened: either an interior fissure opened up, or the impact that originally formed it caused molten lava to seep slowly upward. Oddly enough, Wargentin’s walls lacked large enough breaks to allow the lava to escape and it eventually filled the crater to the rim. Often referred to as “the Cheese,” enjoy Wargentin tonight for its unusual appearance.
Saturday, June 10 – Begin your observations this evening by noting how close Antares is to the Moon. For some very lucky viewers, this means an occultation. Be sure to check IOTA for times and details in your area. You won’t want to miss this event…
Meanwhile on the surface, tonight’s lunar feature will be crater Galileo. It is a supreme challenge for binoculars to spot, but telescopes of any size at higher magnifications will easily reveal it perched on the terminator in the west-northwest section of the Moon. Set in the smooth sands of Oceanus Procellarum, Galileo is a very tiny, eye-shaped crater with a soft rille accompanying it. Of course, this crater was named for the man who first contemplated the Moon through a telescope. No matter what lunar resource you choose to follow, all agree that giving such an insignificant crater a great name like Galileo is like saying a Stradivarius is a stringed instrument! For those familiar with some of the outstanding lunar features, read any account of Galileo’s life and just look at how many spectacular craters were named for people he supported. We cannot change the names of lunar cartography, but we can remember Galileo’s many accomplishments each time we view this crater.
As the father of telescopic astronomy, Galileo blazed a trail across the night sky – one any amateur of the day can easily follow. Among his most well known discoveries were the four bright satellites of Jupiter – the Galilean moons. Of the four, Ganymede is now known to be the largest satellite in the solar system. At 5262 kilometers, Ganymede is significantly more than twice the diameter of Pluto and almost 10 percent larger than Mercury. Of all the satellites in our system other than the Earth’s moon, it is the only one capable of displaying a true disk in a moderate sized telescope. Tonight, at some 1.6 arc seconds in apparent size, Ganymede could reveal its disk to a mid-sized scope. Take the time to observe Galileo’s “solar system within a solar system.” Get a sense of the relative colors, brightness and size. If one of them is missing, Galileo didn’t miscount. Look for a transit shadow cast against the planet’s disk or watch for it to emerge from around behind.
Sunday, June 11– Tonight is the Full Moon. Often referred to as the Full Strawberry Moon, this name was a constant to every Algonquin tribe in North America. Our friends in Europe referred to it as the Rose Moon. The North American version came about because the comparatively short season for harvesting strawberries arrives each year during the month of June.
As its rises, we’ll voyage to something “strawberry” red – the brightest “carbon star” in the night skies. Aim scopes or binoculars about a fist width northeast of Beta Canes Venatici and behold “La Superba.”
Y Canes Venatici is a variable star which ranges between magnitudes 4.8 to 6.3 over a period of about half a year. When “Y” is at minimum it is around 4 times dimmer than at its peak. But, there is something very good about catching this star on a night when it is faint – its distinctive reddish hue. See if you agree with mid-18th century astronomer Father Angelo Secchi, in naming it “La Superba.”
May all your journeys be at light speed… ~Tammy Plotner with Jeff Barbour.