If you are flying west across the United States this month, leaving just at or after sunset, find Venus bright and low in the northwestern sky and see how long it takes to set.
I had the good fortune once to notice the planet Venus just above the western horizon out my window. Normally, Venus would have set in an hour or so, but I was able to watch it set over several hours. Why?
As the aircraft flies westward at 500 mph, it is almost as fast as the earth’s rotation of about 700 mph at mid-latitudes. If you think about it, if the plane flew at the same speed as the earth’s rotation, the sun and stars would appear not to move in the sky. You can use this effect to watch the planet Venus, and around Memorial Day weekend the planets Jupiter and Mercury, very slowly set. Now, at midmonth, Jupiter is low in the west after sunset, but above Venus.
So, if you are flying westward, you are lucky because time, as measured by the sun and stars, appears to slow down (the Concorde supersonic jet would land “before” it took off, based on local time at the departure and arrival cities). You would be doubly fortunate to see the planets hang out for a long time if you are flying westward after sunset.
We’ve had quite a string of sunny days with deep blue skies here in the northeast! Have you noticed that something is missing? Usually on sunny, warm days we get those puffy cumulus clouds later in the afternoon. But we’ve mostly had just blue skies with a trace of high cirrus clouds.
That’s because we’ve been sandwiched between two strong low pressure systems in the jet stream, with a resulting strong high pressure over us. When that happens, the weather patterns stall and we get a long string of whatever weather we are having at the moment.
At this moment, we are having weather more typical of the dry, clear coastal desert of southern California. We are stuck on the eastern side of the jet stream ridge and so we have a steady easterly wind at the surface, which brings in some low clouds at night and temperatures drop to the water temperature and below into the 40s. During the day, the strong upper air high pressure system keeps us sunny and its sinking air suppresses the puffy clouds.
So, it looks like California weather until the jet stream traffic jams unblock!
[An expanded discussion will be in the Almanac column in the upcoming Westchester Astronomers newsletter for May.]
In May, you can stay up all night with Saturn! Not that you would, but it’s nice to know that Saturn, the ringed planet, is there for you. Saturn rises in the east as the Sun is setting. While Saturn is brighter than all but seven stars in our sky, it is not as obvious as outstandingly brilliant Jupiter, in the western sky at sunset. Follow Jupiter this month as it falls down into the twilight brightness, leading us to a three-planet-pile-up low in the west-northwest just after sunset this Memorial Day weekend. Don’t forget to spend some time looking for its brightest moons and the dark cloud bands on the planet.
I often say…..
“Binoculars will help you find [fill in the blank with a great astronomical sight!] low in the twilight sky”
….This time, take my advice over the Memorial Day weekend. About 40 to 45 minutes after sunset, look for the pile-up of bright planets low in the part of the sky just above where the Sun sets. Spying Venus, Jupiter and Mercury, all together in the wide view that binoculars provide, will be worth the need to find a clear western horizon so you can look low in the west northwest. Many popular space websites will show charts with directions.
Saturn is just past opposition, rising at sunset, getting higher in the evening sky this month. A good spotting scope or most telescopes will show the ring that makes Saturn different from the other bright lights in the sky. Saturn is still tiny, even in a telescope, but if you get a steady sky and increase the magnification, Saturn’s rings will show some details and the subtle cloud bands and moons will be visible. Saturn’s Titan is the second largest moon in the Solar System, smaller than the champion, Jupiter’s Ganymede. Titan should be visible in a telescope, and other moons in a larger telescope.
Strange two-faced moon Iapetus is visible to the south of Saturn around May 10th. It moves west of Saturn, brightening to magnitude +10, as it approaches greatest elongation on the 30th. Iapetus’ orbit is tilted compared to the rings, so future Iapetians will have a great view of Saturn’s rings for much of the moon’s 79-day trip around Saturn.
The Moon will have a weak penumbral eclipse near midnight on May 24/25. It will not be noticeable to our eyes. Even on the Moon, it would only be a partial eclipse of the Sun by the Earth, and only visible from the Moon’s South Pole. Of more significance, the Moon is closest to the Earth for May on the 25th, 21 hours after full Moon. The lining up of the Earth, Moon and Sun in a straight line, augmented by a closer than usual Moon, will make tides higher than normal. Also, an annular eclipse of the Sun – not a total eclipse – is not visible here, on the 10th at sunrise in Australia and later in the South Pacific Ocean. While we’re on the subject of things you can’t see, our best meteor shower in May peaks on the 5th. While you might see a few meteors at any time, almost all of the meteors from this shower are visible only south of 40 degrees north latitude.
The crescent Moon makes a nice photo op with Jupiter on the 11th and 12th. The Moon just misses Spica on the 22nd.
Twilight lasts longer as we get closer to the summer solstice on June 21st, more and more earth-orbiting satellites are visible each night, some as late as midnight. The International Space Station is not visible here for the first half of the month; after that, it is seen in the morning sky. In early June, the ISS is visible as often as five times a night, every 96 minutes.
Abrams Planetarium is offering a sky calendar and chart of bright stars in the sky for May at http://www.pa.msu.edu/abrams/. I love their great diagrams of where to find bright objects in the sky. For May, it’s free and you can make copies, this month only! Or you can download a copy, below….
Overexposure can be a problem for photos for a family-friendly web site, but not in this case as Jupiter and the Moon patiently pose together while I fumble with exposures and other camera settings on my wonderful Canon Rebel XS on a sturdy tripod (thanks, kids for that great Christmas present!).
Here’s a 1/2 second exposure, ISO 400, f8 that gives an idea of the scene as seen by the human eye.
Here a close up of the Moon, zooming in with a 250 mm variable lens; f8, 1/80 second, ISO 400, cropped from larger photo…
And the same moon, overexposed (!) to show a lunar mountain as a dot on the left (south) end of the crescent. (Cropped from a larger photo.)
Settings: f8 ISO 400 1/10 second exposure.
Jupiter’s moons are barely visible, even at the 250 mm setting. This is cropped from a larger scene to show the four moons to the lower right of the planet. (Look carefully for the faintest moon, farthest to the right. 1 second exposure at ISO 400.
The ISS (Is Someone Singing?) will be very bright as it passes over the northeastern US on Tuesday evening. The ISS will come from the southwest, passing to the left of Orion, just skimming in front of Jupiter and between the two Dippers.
It will be brighter than Jupiter and easy to see if the clouds stay away.
Here’s a finder chart that may be helpful for the overflight that will last from 8:35 to 8:45 pm give or take five minutes.
If you are observing tonight with us, the Westchester Astronomers (see http://www.westchesterastronomers.org/ ), it’ll be a race to see if the high clouds get there first. But some models hold off the clouds until after midnight, so we are go for viewing tonight, unless the clouds come in ahead of schedule this afternoon.
Here’s a pdf of the star chart for this evening, from Sky and Telescope….
skychartPDF ap 06 2013
Astronomical Twilight ends (Sun 12 degrees below the horizon): 9:05pm
We should be able to get Comet PanSTARRS in our telescopes by 8:30. Bring binoculars for a good view!
PanSTARRS sets just after 10pm. It rises again after 2:30am, in case you want to see it in the morning sky as well
Jupiter will be high up in the sky, visible even as the sky is getting dark. Here’s a chart of where it’s four brightest moons will be as seen in a telescope….
Saturn will rise after 9:10pm. It may look a bit fuzzy, so low in the sky, but this chart shows its moons and rings as they might look in a telescope (at high magnification, to show details)…
The sky chart will be good for a week or so for evening skies from locations near latitude 40 degrees north.
Jupiter’s moons move enough to be noticeable even over several hours, so the chart with Jupiter’s moons is best for this evening and will change, as Saturn’s moons, each night. Sky and Telescope and other web sites have maps of the moons’ positions for other times.
You haven’t seen Comet PanSTARRS yet!? You are not alone. I did finally find it on March 27th, after despairing over cloudy evenings and desperately peering into murky evening twilight on several occasions before that. If you want to see the comet, find someone who has seen it or check out websites that have good instructions for finding it, like AstroBob in Duluth (not related), or SpaceWeather.com. About an hour after sunset, find a location with a clear northwestern horizon, about 30 degrees to the right of where the sun set. Scan the sky near the northwestern horizon, with binoculars. Binoculars give a wide view of the sky and make the search easier. Look for a fuzzy star that looks like it has a faint spray of light to its upper right.
But, easier-to-find objects are available every month and this one is no different. Everyone notices Jupiter, high in the southwest. Find Jupiter and look nearby for the V-shaped Hyades and the tiny dipper-shaped Pleiades. Saturn is waiting its turn to rule the post-twilight skies in April and May. We make our annual closest approach to Saturn late this month, ‘only’ 800 million miles away. It takes a telescope to tell it’s a ringed planet, but people are always amazed that they can see the rings for themselves, despite how tiny the planet may look, even in a telescope.
Venus is in the solar glare most of the month, along with Mars and Uranus. But you can use the SOHO solar observing spacecraft’s cameras to see them. At their web site, click on the C3 camera, which in addition to showing solar coronal mass discharges, shows the dim stars behind the Sun in the sky, allowing you to observe next to the Sun with no threat to your eyesight. Venus and Mars are obvious to see, overwhelming SOHO’s camera. For Uranus, you’ll need a chart with the latest positions of the planet to find it.
Here’s a set of photos I downloaded from the SOHO gallery page with the planets back on March 22nd. First, here’s a map of where the planets are from the Cartes du Ciel planetarium program:
Here’s the photo from SOHO C3:
The position of the Sun is marked by the center white circle. To the lower right of the Sun is Venus, overpowering the detector. To the left is Mars. When this photo was taken, Uranus was in conjunction with Mars – it’s the tiny dot next to Mars in these magnified sections of two SOHO C3 photos taken 11 hours apart on March 22nd. Mars passes by more distant Uranus between these two photos.
Back to the rest of the sky…..
Mercury is low in the morning sky, a hard to find binocular object. Surprisingly, it’s the closest planet to Earth, and has been since the beginning of the year and will be through late August.
On the 24th, the Moon is right next to the first magnitude star Spica, drowning it in a puddle of Moonlight. But other Moon scenes can be photogenic. Can you get your camera to take photos of the sky? Most times, the Moon overwhelms the fainter star clusters nearby, but on the 13th and 14th, the Moon’s thinner crescent phase allows the clusters to shine through, and with bright Jupiter nearby, it’s a good time to see if you camera can catch a sky scene. A fuller, brighter Moon makes a dot at the bottom of the backwards question mark of the lion’s head in Leo on the 20th.
The International Space Station passes through the dawn sky through the 6th and during dusk from 6th through the 26th. Tiangong 1 is an evening flyer from the 4th through 17th. Can you find times when the ISS and the Chinese space station will be in the sky at the same time? See websites like heavens-above.com for updated times when you can see them.
You can copy this Heads UP! for your use, and if you publish it elsewhere, give credit to Bob Kelly at bkellysky.wordpress.com
Wednesday evening, about 8:10pm, about one hour after sunset, I came upon a small, fuzzy star, with a faint fan-shaped glow extending to its upper right. Attached are some photos, but it was better in my 8×25 Canon Image Stabilized binoculars. The comet set behind our high school building about 8:40pm. I tried a number of different lenses and exposures and here’s the best I got…..
Cropped from larger photo (the next photo, below) F5.6, 5 seconds exposure, 55mm zoom lens, ISO-800. The fuzzy dot on the right is the comet. It had a longer fan-like tail in binoculars.
I tried a zoomed in view with a longer lens, but here’s the blurry result, as the comet started lowering below the roof of the school.
250mm lens, f5.6 15 seconds (the stars and comet have trailed because of the long exposure with the long lens) ISO-800.
Bonus photo of the full moon with the 250mm zoom lens – cropped from an original which was a much shorter exposure for the sooooooo much brighter moon.
Original was 1/1000 second exposure at ISO-800 f 5.6.
The latest winter storm to intrude on our transition to Spring has started with a burst of snow in Washington, DC, now moving through Baltimore and may reach as far north as central New Jersey.
We are awaiting the formation of a secondary storm off the Maryland/Delaware coast. Indications are that the storm will stay just far enough off the east to limit accumulating snow in the NYC/Long Island/New England area to the coastal areas, with little accumulations inland. Even at the coast most of the snow will just stick to grassy surfaces.
Roads should be mostly clear, but watch out when you drive over overpasses and bridges that may be slick as the falling snow chills the overpasses.
Check your NWS local forecast for details and updates!
After the storm, high temperatures go to the mid-40s, and 50′s by the weekend, warmer than the last few weeks, but still cooler than normal.
Tech details from the NYC forecast discussion:
THE NAM MAINTAINS A RATHER SHARP GRADIENT KEEPING
MOST OF THE PRECIPITATION OFF THE COAST. WHILE THE GFS AND ECMWF
BRING HIGHER QPF [precipitation] ACROSS LONG ISLAND AND THE CITY. STILL EXPECT
AROUND A HALF INCH LIQUID WITH 2 TO 3 INCHES OF WET SNOW. WILL KEEP
THE ADVISORY IN PLACE FOR TODAY AND TONIGHT. LESS CONFIDENT THAT
NORTHWESTERN PORTIONS OF THE ADVISORY…IE..WESTERN NEW
JERSEY…WILL SEE ADVISORY LEVEL SNOWFALL [2 inches or more].
BEST FORCING WILL BE
ACROSS NEW YORK CITY AND LONG ISLAND…WITH LITTLE FARTHER TO THE
NORTH. INLAND AREAS MAY SEE LESS THAN AN INCH OF SNOW…SO WILL NOT
EXPAND THE ADVISORY FROM CURRENT AREAS.
WILL BECOME WINDY AS THE LOW NEARS THE AREA LATE THIS
MORNING…HOWEVER WINDS WILL LIKELY REMAIN BELOW ADVISORY LEVELS
WITH THE HIGHEST WINDS RIGHT ALONG THE SOUTH SHORE OF LONG ISLAND
AND INTO NEW YORK CITY WITH MAX GUSTS 40 TO 45 MPH.