Archive
08/15/2014 – Ephemeris – Jupiter and Venus will appear to cross paths Monday morning
Ephemeris for Friday, August 15th. The sun rises at 6:45. It’ll be up for 14 hours and 2 minutes, setting at 8:47. The moon, 2 days before last quarter, will rise at 11:33 this evening.
Over this weekend the planets Venus and Jupiter will be seen to approach each other. In reality Jupiter is five times the Earth’s distance behind the sun, while Venus is about 70 percent of Earth’s distance behind the sun. Most of the motion against what stars can be seen after 5:30 a.m. will be Venus, being dragged by the sun plus its own orbital motion toward the east. Jupiter is moving eastward too, but is taking its sweet time of 12 years to orbit the sun. The planets will cross, or be in conjunction at about midnight Monday morning, before they rise. By the time they will rise around 5:12 a.m. the two planets will be half the width of the Moon apart, slightly farther apart than they were at midnight.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Watch Jupiter and Venus approach each other and separate. From August 15 to August 18, 2018. Created using Stellarium and GIMP.
08/14/2014 – Ephemeris – The Milky Way now spans the sky in the evening
Ephemeris for Thursday, August 14th. The sun rises at 6:43. It’ll be up for 14 hours and 5 minutes, setting at 8:49. The moon, 3 days before last quarter, will rise at 10:58 this evening.
We’ll get a bit of darkness tonight, but it will be the start of about two weeks of the best sky viewing of the year. Now is the time the summer Milky Way is displayed to its fullest to the southern horizon. City folk come to our area and are sometimes fooled by the brightness and expanse of the Milky Way and think it’s clouding up. Yes those are clouds indeed, but they are star clouds. Binoculars will begin to show them to be millions of stars, each too faint to be seen by themselves to the unaided eye, but whose combined glow give the impression of a luminous cloud. Binoculars are the ideal tool to begin to explore the Milky Way. Objects still too fuzzy can be checked out with a telescope to reveal their true nature.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Milky Way at 10 p.m. on August 14, 2014. Residual glow in the west is from the Sun, to the east is for the Soon to rise Moon. There is also an odd artifact connected to the solar glow. Created using Stellarium.
08/13/2014 – Ephemeris – This week’s parade of the bright planets
Ephemeris for Wednesday, August 13th. The sun rises at 6:42. It’ll be up for 14 hours and 8 minutes, setting at 8:51. The moon, 3 days past full, will rise at 10:24 this evening.
Wednesday is bright planet day on Ephemeris. Reddish Mars is between the constellations of Virgo and Libra, approaching Saturn in the southwest as darkness falls. It will set at 11:40 p.m. Saturn will be in the southwest, above and left of Mars as darkness falls, in the Libra the scales. It will set at 12:16 a.m. Saturn’s is still great viewing with small or large telescopes to see those fabulous rings and its large moon Titan. Mars will pass Saturn traveling eastward later this month on the 27th. Brilliant Venus will rise in the east-northeast at 5:03 a.m. in morning twilight. Below left of Venus, we welcome back Jupiter which will rise at 5:23 tomorrow morning. Jupiter and Venus will appear to cross paths on the 18th.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars and Saturn with the zodiacal constellations Virgo, Libra, Scorpius and Sagittarius at 10 p.m. August 13, 2014. Created using Stellarium.
Saturn and its moons. Small telescopes will reveal only Saturn and Titan. Created using Stellarium.
The Moon low in the east at 11 p.m. Created using Stellarium.
Venus and Jupiter at 6 a.m. in the bright morning twilight with the rising stars of winter. Created using Stellarium.
08/12/2014 – Ephemeris – Comet Swift-Tuttle progenitor of the Perseid meteors
Ephemeris for Tuesday, August 12th. The sun rises at 6:41. It’ll be up for 14 hours and 11 minutes, setting at 8:52. The moon, 2 days past full, will rise at 9:50 this evening.
The Perseid meteor shower will reach its peak later this evening. The moon will still interfere with all but the brightest meteors. The meteors are caused by bits of sand grain to pea sized rubble given off by Comet Swift-Tuttle on past runs through the inner solar system. As comets go Comet Swift-Tuttle is large, with a nucleus of some 16 miles (26 km) in diameter. Comet Halley’s nucleus is half that and Churyumov–Gerasimenko’s nucleus that ESA’s Rosetta spacecraft is now orbiting is half Halley’s. Despite the wear and tear that a comet’s nucleus must endure when coming close to the Sun, the distribution of debris to give us a pretty even annual meteor shower means the comet has been near its present orbit for a very long time.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orbit of Comet 109P/Swift-Tuttle. Blue line is the comet’s orbit, coming from above. Credit NASA / JPL / Applet by Osamu Ajiki (AstroArts), and further modified by Ron Baalke (JPL)
Link to the animation from which the above image was taken and other information on Comet Swift-Tuttle go to http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=109P;cad=1
08/11/2014 – Ephemeris – The Moon’s terminator is now the sunset line
Ephemeris for Monday, August 11th. The sun rises at 6:40. It’ll be up for 14 hours and 13 minutes, setting at 8:54. The moon, 1 day past full, will rise at 9:15 this evening.
After the full moon the shadow action moves from the eastern or left edge of the moon to the western or right edge of the moon, or if the moon’s low in the east, to the upper right edge. For the first two weeks of the lunar cycle, from new to full we were watching the sunrise terminator slowly sweep across the face of moon. Now, after full the sunrise terminator is sweeping across the Moon’s far side, and the sunset terminator is beginning to sweep across the near side, our side of the Moon. Tonight the terminator is approaching the small Sea of Crises on the upper right of the Moon. By tomorrow night the terminator will be half way across that sea. By Wednesday it will be lights out for the Sea of Crises for two weeks.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The moon at 10 p.m. tonight, August 11, 2014. Created using Virtual Moon Atlas.
The moon at 10 p.m. tomorrow night, August 12, 2014. Created using Virtual Moon Atlas.
Supermoon, Smoopermoon
Pardon me if I don’t get excited by the fact that we are going to have a “supermoon” August 10th. On the night of the full moon it will be at perigee, its closest point to the Earth in its orbit. The distance according to our Celestial Calendar page is 356,897 kilometers. That’s 221,766 miles. At apogee this month, on the 24th, the moon will be 406,523 kilometers, or 252,602 miles away. That’s somewhat larger than 11 percent difference in distance, due to the Moon’s elliptical orbit. The name for the smallest moon is micromoon. Either is an exaggeration of terms.
A supoermoon compared to a micromoon. Credit: Michael Myers.
I don’t remember the supermoon term growing up. Wikipedia says it was coined by astrologer Richard Knolle in 1979 according to his web post from 2011. Oooo, an astrologer.
There’s a profession astronomers can respect. </snark>*
Being a relatively old guy, 1979 was well past my formative years as an amateur astronomer and even four years after I started producing my Ephemeris programs for Interlochen Public Radio. Yet I only remember supermoon being a big deal or any deal at all for the last few years.
The actual size of the supermoon aside, folks mistake the normal optical illusion of an enlarged moon rising as the supermoon. The moon always looks larger when it’s near the horizon than when it’s high in the sky. The same thing happens to the sun, it looks larger rising and setting, the when higher in the sky. Caution: Use a solar filter to observe the sun. In photographs the Moon is the same size whether on the horizon or high in the sky. Actually the horizon moon will appear slightly smaller on the horizon. One, it will be squished vertically by the action of the refraction of the earth’s atmosphere. Two, it is nearly 4,000 miles farther away at the horizon than at he zenith, where we’re the radius of the Earth closer to the Moon.
I challenge anyone to be able to actually detect, by looking at the moon in the sky, whether they are looking at a supermoon or not. There’s nothing of comparable size out there. The same thing will happen when one thinks the full moon is so white. OK, there’s some gray too. However the Moon’s total albedo of reflectance is 0.136 or 13.6%. Some say 0.07 or 7%, comparable to a charcoal briquette. If one could get Saturn’s moon Enceladus, with nearly a 100% albedo, next to the Moon without it turning into a comet by sublimating away, the dinginess of our Moon would be immediately obvious.
08/08/2014 – Ephemeris – Supermoon plus astronomical fun in the Grand Traverse Area
Ephemeris for Friday, August 8th. The sun rises at 6:36. It’ll be up for 14 hours and 21 minutes, setting at 8:58. The moon, 2 days before full, will set at 5:17 tomorrow morning.
In two days the Moon will reach perigee within a few hours of being a full moon. This has become known as a supermoon. Perigee is the point where an Earth orbiting object is closest to the Earth. The farthest point is called apogee. The coincidence of full moon and perigee was coined as the supermoon by astrologer Richard Knolle in 1979, but apparently didn’t catch on until he wrote a popular article in 2011. No wonder I hadn’t heard of it, this program had been on for 4 years before the term was even coined. The problem with appreciating the supermoon is the lack of a reference of nearly the same size. The moon always looks large when it’s near the horizon. It’s a well-known optical illusion, It’ll fool us every time.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturday evening the 9th the Grand Traverse Astronomical Society (GTAS) will host a Sun and Star Party at Thoreson Farm at the Sleeping Bear Dunes National Lakeshore. It’s the concluding event at the Port Oneida Fair. Solar viewing will be from 4 to 6 p.m., and the evening event will run from 9 to 11 p.m. with the main attraction will be the nearly full Moon, the planet Saturn and colorful binary stars and bright star clusters. Thoreson Farm is located on South Thoreson Road. South Thoreson Road runs into M22, about a mile west of Port Oneida Road.
Sunday evening the 10th the GTAS will attend the Meteors and S’mores event at the Leelanau State Park at the tip of the Leelanau Peninsula. The event will run from 8:30 p.m. to 11:45 p.m. The Perseid meteor shower will reach peak a couple of days later, but there will still bright Perseids visible to the vigilant.
I’ll have more to say about the supermoon tomorrow in a non-Ephemeris post.
The Rubber Ducky turns out to be kind of an Ugly Duckling
The European Space Agency’s Rosetta spacecraft arrived at its target Comet 67p/Churyumov–Gerasimenko yesterday, August 6th, 2014. The smoothed image 30 pixels across of three weeks ago of a rubber ducky,
An animation of Comet 67p/Churyumov–Gerasimenko rotation on July 14, 2014. The 30 pixel wide image has been smoothed. The Rotation rate is 1 rotation every 12.4 hours. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
have been replaced by the mega-pixel images we see now of an Ugly Duckling comet, with much more character and battle scars. That’s what happens when you’ve been ’round the Sun to many times.
The comet on August 3rd, 2014, 3 days before arrival. Credit: ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA
See Emily Lakdawalla’s post from yesterday at http://www.planetary.org/blogs/emily-lakdawalla/2014/08060249-were-at-the-comet-rosetta.html. It contains lots of images and more information including a 3D image. Grab your red & blue 3D glasses for that one, or if you’ve mastered the techniques of crossed-eye, or parallel-eye stereo viewing.
Also go to ESA’s own Rosetta site at http://www.esa.int/Our_Activities/Space_Science/Rosetta.
I find Emily’s post much more comprehensive. So subscribe to the Planetary Society’s blog feed.
08/07/2014 – Ephemeris – Two large craters of the lunar highlands visible tonight
Ephemeris for Thursday, August 7th. The sun rises at 6:35. It’ll be up for 14 hours and 24 minutes, setting at 8:59. The moon, 3 days before full, will set at 4:07 tomorrow morning.
The gibbous Moon is getting brighter as it becomes more sunlit from the Earth’s prospective. The disk of the Moon will be 89 percent illuminated by the sun tonight. The bright crater Aristarchus, which I’ve talked about before, on the upper left of the moon is now in sunlight. On the lower left there are two interesting craters for the small telescope. Split in half by the sunrise line terminator is the large crater Schickard 137 miles (227 km) in diameter. Craters near the limb of the Moon are foreshortened by the fact that the Moon’s nearly spherical so they there appear elongated. One, more elongated than most, is nearby Schiller which is actually 108 by 43 miles (179 by 69 km), which may be two overlapping craters or a really low angle asteroid impact.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The lunar craters Schickard and Schiller on the lunar terminator at 10 p..m., August 7, 2014. Created using Virtual Moon Atlas.
The craters Schickard and Schiller from the Lunar Reconnaissance Orbiter. Credit NASA from Virtual Moon Atlas.
08/06/2014 – Ephemeris – Wednesday is bright planet day on Ephemeris
Ephemeris for Wednesday, August 6th. The sun rises at 6:34. It’ll be up for 14 hours and 26 minutes, setting at 9:01. The moon, 3 days past first quarter, will set at 3:03 tomorrow morning. | Wednesday is bright planet day on Ephemeris. Reddish Mars is in Virgo in the southwest as darkness falls. It’s 113 million miles (183 million km) away now, over twice as far as it was last April, and will set at 11:58 p.m. Saturn will be low in the south-southwest as darkness falls, in the faint constellation of Libra the scales. It will set at 12:43 a.m. Saturn’s great viewing with small or large telescopes to see those fabulous rings and its large moon Titan. Somewhat larger telescopes can spot some smaller moons closer in. Brilliant Venus will rise in the east northeast at 4:47 a.m. in morning twilight. Dark skies for the Perseid meteor shower will run from 3:03 a.m. to 4:34 a.m. Bright meteors will be visible all night.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The planets Mars and Saturn with the bright stars and the Moon at 10 p.m., August 6, 2014. Created using Stellarium.
Saturn and its satellites through a telescope as seen on the evening of August 6, 2014. Created using Stellarium.
The Moon as it would be seen in binoculars at 10 p.m. , August 7, 2014. Created using Stellarium.
Venus and the constellations of winter rising in morning twilight at 5:30 a.m., August 7, 2014.
Bob Moler's Ephemeris Blog 