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2dimes wrote:I wonder how much you need to spend on a telescope to view Saturn's moons?
jonesthecurl wrote:Here is something very lovely.
https://petapixel.com/2019/09/09/this-video-was-made-from-400000-actual-photos-of-a-comet-in-space/?fbclid=IwAR1E5z-E6662aZu9ZtaKYQkAGfPUtPWHyd-6vARFvfeQc_r3yslmyRsZBY0
By the 11th, Mars has pulled away from Saturn so that the three form an almost evenly spaced line. The spacing is almost perfectly even on the morning of the 9th.
■ Venus this evening shines in the upper left edge of the Pleiades, as shown above. How soon before the end of twilight can you first begin to see the little cluster? Bring your telescope, binoculars, and/or long-focus camera! This is a once-in-eight-years event. For more see Bob King's The Pleiades Welcome Venus, with photo tips.
Of course they're nowhere near each other, really. Venus this evening is 5.2 light-minutes from us, while the Pleiades are 440 light-years in the background. That's 45 million times farther away. To put this in scale-model perspective: If Venus were a shiny dust speck floating three inches in front of your eye, the Pleiades stars would be 1,200 miles behind it halfway across the continent: blue-white-hot marbles and peas, searingly brilliant, scattered in a volume of black space about 30 miles wide.
Also in and around this volume would be scores of dimmer, yellow-hot BBs and orange-hot mustard seeds, and roughly a thousand much dimmer, merely red-hot sand grains.
On average, each would be a few miles from its nearest neighbor.
Venus passes through the Seven Sisters’ territory tonight, slipping among the bright Pleiades (M45). This young cluster of stars is more than 400 light-years from Earth and thought to have formed about 100 million years ago. Tonight, magnitude –4.6 Venus will hang just 15', or half the diameter of the Full Moon, from magnitude 2.9 Alcyone, the grouping’s brightest star. As twilight falls, you’ll easily spot the bright planet nearly 45° above the horizon, glittering just southeast of the cluster’s dipper shape.
Venus will continue to brighten subtly throughout the month. The planet reaches greatest brilliancy on the 27th.
A triple delight before dawn
The three bright morning planets spread out a bit in April, with Saturn perching midway between Jupiter and Mars on the 9th.
The Sky This Week from April 10 to 17
Chase down star clusters in Cassiopeia and start searching for Lyrid meteors in the sky this week.
By Alison Klesman | Published: Friday, April 10, 2020
RELATED TOPICS: OBSERVING
Mars, Jupiter, and Saturn (magnitudes, +0.6, – 2.2, and +0.6, respectively) are lined up in the southeast before and during early dawn, as shown below. Each morning Mars moves a little farther away from the other two.
Venus (magnitude –4.6, in north-central Taurus) is the dazzling white "Evening Star" high in the west during and after dusk. Venus doesn't set in the west-northwest until about 2½ hours after complete dark. Look below it for the Pleiades.
Friday, April 10
■ Venus continues to blaze in the west during and after twilight, as shown above.
■ Right after dark, Orion is still well up in the southwest in his spring orientation: striding down to the right, with his three-star belt horizontal. The belt points left toward Sirius and right toward Aldebaran and, farther on, Venus .
Look at Orion's two shoulders. Orange Betelgeuse is obviously brighter than Bellatrix to its lower right, now that Betelgeuse has been recovering its brightness for the last two months. In early February it bottomed out at magnitude 1.6, as dim as Bellatrix. As of April 5th Betelgeuse was back up to 0.7, almost normal. It's now obviously closer in brightness to Rigel (0.2) than it is to Bellatrix.
Friday, May 20
Wednesday, May 13
■ This is the time of year when Leo the Lion starts walking downward toward the west, on his way to departing into the sunset in early summer. Right after dark, spot the brightest star fairly high in the west-southwest. That's Regulus, his forefoot.
■ Before and during early dawn Thursday and Friday, the waning Moon accompanies Mars as shown above.
Thursday, May 14
■ A gigantic asterism you may not know about is the Diamond of Virgo, some 50° tall and extending over five constellations. It now stands upright in the south after dark. Start with Spica, its bottom. Upper left from Spica is bright Arcturus. Almost as far upper right from Arcturus is fainter Cor Caroli, 3rd magnitude. The same distance lower right from there is Denebola, the 2nd-magnitude tail-tip of Leo. And then back to Spica.
The bottom three of these stars, the brightest, form a nearly perfect equilateral triangle. Maybe we should call this the "Spring Triangle" to parallel those of summer and winter?
■ Last-quarter Moon (exact at 10:03 a.m. Eastern Daylight Time). Tonight the Moon rises very late, around 3 a.m. Friday morning daylight-saving time, by which time it will be visibly a little past first quarter, as shown above. And Mars will be upper right of it.
Friday, May 15
■ A naked-eye Venus challenge! All week, the large, thin crescent shape of Venus is easy to discern with even a very small telescope or good, steadily braced binoculars. But can you resolve its crescent with your unaided eyes? Mere 20/20 vision isn't good enough; success may await the eagle-eyed with 20/15, 20/12, 0r (rare) 20/10 vision. Try during different stages of twilight before the sky is too dark and Venus's glare becomes overwhelming. Look long and carefully and report your results to Sky & Telescope's Bob King, nightsky55@gmail.com, as told in the May issue, page 49.
You may improve your chances by sighting through a clean, round hole in a stiff piece of paper 1 mm or 2 mm in diameter (try both). This will mask out optical aberrations that are common away from the center of your eye's cornea and lens.
One person who apparently succeeded was Edgar Allan Poe. An amateur astronomer since boyhood, he used a naked-eye sighting of Venus's crescent as the central event in his poem "Ulalume" (1847). Before dawn, a bereaved lover roams an October woodland "with Psyche, my soul." Ahead of them low in the east, where Leo always ascends in mid-autumn, they witness the new-risen Venus, star of romantic love in Roman mythology, coming "up through the lair of the Lion." Poe refers to the planet as Astarte, the wilder, more wanton Greek version of the Roman Venus-goddess:
At the end of our path a liquescent
And nebulous lustre was born,
Out of which a miraculous crescent
Arose with a duplicate horn—
Astarte's bediamonded crescent
Distinct with its duplicate horn.
Poe compares its passionate brilliance to cooler, less dazzling Dian, the horned crescent Moon, and urges Psyche forward:
Let us on by this tremulous light!
Let us bathe in this crystalline light!
But Psyche, who knows better, is terrified, and this being Poe, it doesn't end well.
After passing perihelion (its closest point to the Sun) last week on May 4, Comet PanSTARRS (C/2017 T2) is at peak brightness this month, reaching magnitudes 8 to 9. The best time to spot the comet today is in the morning between midnight and moonrise (shortly after 2:30 A.M. local time), or again after the sky darkens following sunset tonight. Currently in the constellation Camelopardalis, PanSTARRS is always above the horizon for most U.S. observers, so it’s just a matter of finding a time when the sky is dark enough to see it with your scope.
PanSTARRS is relatively easy to find using the bowl of the Big Dipper. Swing your telescope from Dubhe, the bright star that forms the upper right corner of the bowl, about 17° northwest to spot this inner solar system visitor. If you have trouble finding it or experience poor weather, don’t despair. In one week, New Moon will occur as the comet skims by a famous pair of galaxies (M81 and M82) in Ursa Major, making it both easier to find and creating an enjoyable tableau.
Tuesday, May 19
Jupiter and Saturn rise in the southeast not long after local midnight, climbing higher in the sky as the morning hours tick by. The gas giants stand about 4.7° apart, glowing at magnitudes –2.5 and 0.5, respectively.
Wednesday, May 20
The Moon passes 4° south of Uranus at noon EDT today. However, the second-to-last planet rises with the onset of twilight this month and is difficult to spot in the brightening sky.
This evening, consider hunting down history by looking north to find the Little Dipper. At the end of its handle, Polaris is Earth’s current North Star. But as Earth spins, it wobbles, causing its poles to trace out a slow circle in the sky that takes about 26,000 years to complete. Along this circle you’ll find past and future North Stars, including magnitude 3.7 Thuban (Alpha Draconis) in Draco the Dragon. Thuban sat above Earth’s North Pole around the year 2700 B.C. Much more recently, NASA’s Transiting Exoplanet Survey Satellite, TESS, discovered that Thuban is an eclipsing binary system. Although astronomers knew Thuban has a smaller binary companion, they had never before seen the stars crossing paths. Each eclipse lasts only six hours.
THURSDAY, MAY 21
■ Venus and Mercury are in conjunction in the west-northwest in evening twilight, as shown above. Venus outshines Mercury by 30 times, something the illustration does not convey. Although they look close together, Mercury is on the far side of the Sun from us while Venus is now on the near side. So Mercury this evening is 3.5 times more distant. It's 9.1 light-minutes from us, compared to Venus's distance of 2.6 light-minutes.
SUNDAY, MAY 24
■ Now the thicker crescent Moon hangs upper left of Mercury and Venus. It aims its sunlit edge almost straight at them, as shown above.
