Monday, May 25, 2015

Tonight's Sky for May 25: First Quarter Moon

Today, the Moon, second brightest object in the sky, has reached the First Quarter phase, which means that it is exactly 90 degrees around its orbit of Earth and is one quarter finished with its current orbit..

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth-Sun line, we only see half of the lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward Full in a week.

Friday, May 22, 2015

Tonight's Sky for May 22: The Summer Triangle is Well up by Midnight

Summer may be a month away but don't tell that to the stars as the Summer Triangle, composed of 3 first and brighter magnitude stars, is now well clear of the Eastern horizon by midnight. Want to see it? Go out about midnight and look East, you can't miss it!

Thursday, May 21, 2015

Tonight's Sky for May 21: Moon Splits Venus and Procyon


This evening will feature a cosmic show that features three of the brightest objects in the sky as the Moon will park itself right between the planet Venus, second from the Sun and third brightest object in the sky, and Procyon, alpha star of the winter constellation Canis Minor, the small dog. To see the line-up, simply go out after the sky starts to get reasonably dark and look West to find the Moon. To the right and slightly above Luna is Venus and, about the same distance and slightly down from Luna to the left is Procyon, which serves as another reminder that the winter constellations are quickly diving into the twilight, making it all the more important to get a last look at them now.  

Wednesday, May 20, 2015

Tonight's Sky for May 20: Venus and Jupiter are Separated by 40 Degrees

Tonight, Venus and Jupiter, 3rd and 4th brightest objects in the sky and 2nd and 5th planets from the Sun, respectively, will be separated by about 30 angular degrees. Now, while that's nothing unusual in itself, the planets will continue to converge, coming to within a fifth of a degree of each other by the end of June, which means that it could be fun to observe and photograph (it's easy!) the planets over the course of the next 6 weeks or so. 

Tuesday, May 19, 2015

Tonight's Sky for May 19: Fatter Thin Moon

Yesterday night offered arguably what is the Holy Grail of naked eye astronomy: a true Young Moon under 24 hours old (last night's Moon was 22 hours past New). While tonight's Moon is not a challenge to see at all, it is still nonetheless quite aesthetic in appearance as it is still only 5% lit tonight. To see it, just head out about 30 minutes after sunset and look low in the West.  

Monday, May 18, 2015

Tonight's Sky for May 18: True Young Moon



How thin of a Moon have you seen? How about one that's less than a day old and only 2% illuminated? Well, if you have never seen a Moon this thin, tonight's your chance to do so as such a Moon will be making an appearance in this evening's sky just after sunset.

To see the Moon, you'll need a good Northwestern horizon. How good? One with less than 3 degrees of obstruction. To simulate this, hold a little finger out at arm's length to simulate 1 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, be there at sunset and start scanning the horizon with your binoculars.

Don't see the Moon right away? Don't panic, as the sky dims, the Moon will get easier to see, which means that it will often just suddenly 'pop' out of the darkness. Believe me, when it does, it's an exhilarating experience.  

Sunday, May 17, 2015

Tonight's Sky for May 17: New Moon

Today, the Moon, second brightest object in the sky, has reached the New Moon phase, which means that it is directly between the Sun and Earth, and thus invisible for us Earthlings as of now. 

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon directly between the Earth and Sun, e can't see any of its lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward first quarter.

Friday, May 15, 2015

Tonight's Sky for May 15: Northern Lights of Historic Proportions (2005)


It was 10 years ago today that a historic display of the Northern Lights took place. The best part: thanks to technology, we have day by day accounts of the event.

Everything started a few days before the big light show. At the time, we were on the downward trend for extremely strong sunspot cycle 23, which stands in stark contrast to current cycle 24, one of the weakest ever seen in recorded history. It was on May 13 that sunspot 759 erupted a M8 class solar flare accompanied by a coronal mass ejection (CME) that was hurled into space directly towards Earth. Interestingly enough, while there was an increased chance for geomagnetic activity, no one expected anything unusual because, after all, the flare was only a M8.

Boy, how everyone was wrong!


Then, on the night of Saturday and into Sunday (the 15th) morning, the skies over the United States erupted with brilliant displays of the Lights as far South as Florida and Arizona. Depending on location and atmospheric composition, the colors included reds, oranges, greens, blues, and even purples. It was on this night that yours truly saw his only display of Aurora. In my neck of the woods in Northeast Ohio, the Lights were a mix of violet and blue overhead, gradually blending into green curtains as they approached the horizon. I remember vividly being a bit dumbfounded as to what the lights were at first, only realizing that these were the Lights after a moment or so. First seeing them at around 4am, I stayed up until dawn, at which the brilliant display was out-shown by the Sun.

Hopefully, such a sight will repeat itself soon, we're long overdue in these parts . . .
 

Thursday, May 14, 2015

Tonight's Sky for May 14: The Teapot Due South at Dawn



As a sign that summer is on the way in about a month and a half, the predawn sky presents Sagittarius due South at dawn. To see the constellation (or more specifically its bright Teapot asterism), look due South just as the sky starts to brighten in the morning.  

Wednesday, May 13, 2015

Tonight's Sky for May 13: Corvus Due South at Dark


A sign that spring is here presents itself as soon as the sky gets dark. Corvus, a small but bright trapezoid of stars that represents a cosmic crow is low and just about due South once the sky gets truly dark, about 1-1½ hours after sunset. For people with a telescope, Corvus features one of the sky's best deep sky objects: the Sombrero Galaxy. Thanks to its low position in the sky, be sure to get out and view Corvus as it won't stick around for too long.  

Tuesday, May 12, 2015

Tonight's Sky for May 12: Venus and Jupiter are Separated by 40 Degrees


Tonight, Venus and Jupiter, 3rd and 4th brightest objects in the sky and 2nd and 5th planets from the Sun, respectively, will be separated by about 40 angular degrees. Now, while that's nothing unusual in itself, the planets will continue to converge, coming to within a fifth of a degree of each other by the end of June, which means that it could be fun to observe and photograph (it's easy!) the planets over the course of the next 7 weeks or so.

Monday, May 11, 2015

Tonight's Sky for May 11: Last Chance to Catch Gemini Under a Dark Sky


The times are a changin' and it shows in the sky. Want proof? Look West just after it gets truly dark and spot the prominent winter constellation Gemini. Mid may presents the last chance to catch Gemini under a dark sky so take a moment to go out and take a look before it begins its annual dive into the solar glare. 

Sunday, May 10, 2015

Tonight's Sky for May 10: Third Quarter Moon

Today, the Moon, second brightest object in the sky, has reached the Third Quarter phase, which means that it is exactly 270 degrees around its orbit of Earth.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth and Sun, we see the Moon as half lit and half dark, leading to the popular, erroneous phrase 'half Moon.'

After today, we will see less and less of the Moon as its lit side turns more away from us and heads toward a new lunar cycle. 

Friday, May 8, 2015

Tonight's Sky for May 8: Mariner 8 Launched (1971)

It was on this date in 1971 that NASA launched its Mariner 8 spacecraft which, along with Mariner 9, made up the Mars 71 Program. Unfortunately, the mission never reached orbit thanks to the rocket spinning out of control scarcely 6 minutes after launch. Instead of entering orbit around Mars, Mariner 8 entered the Atlantic Ocean about 800 miles downrange from its launch pad.


Fortunately, Mariner 9 was a complete success, becoming the first probe to enter orbit around another planet (while beating a pair of Russian probes by just a few days, to boot) and, over the course of its nearly year-long stay, returned over 7,300 pictures, and mapped roughly 85% of the Martian surface despite the first several months of the mission being fruitless thanks to a months-long Martian dust storm.

Thursday, May 7, 2015

Tonight's Sky for May 7: Mercury at its Best, Sets 2 Hours After the Sun


Want to join a small club of people who have seen the planet Mercury? Well, here's your chance as the first planet from the Sun will be making its best appearance of the fall this morning.

Of all the Classical Planets (those known to the Ancient Greeks and Romans), Mercury is by far the hardest to spot because, as seen from Earth, it never gets very far away from the Sun. As a result, Mercury is often obscured from view by the Sun's glare.

As of today, Mercury has reached a point in its orbit called greatest elongation, which is a fancy way of saying that, as seen from Earth, Mercury is as far from the Sun as it will get on this orbit and making its best morning appearance of the year. How good is it? So good that Mercury sets about an hour and a half after the Sun! So good that, even 30 minutes after sunset, Mercury is still about 10 degrees up from the horizon. To simulate, hold your fist vertically at arm's length. While that may not seem overly high, for elusive Mercury, that's quite good.


So, take a moment or two, go out just before dawn, and try to spot Mercury. If you are successful in spotting the speedy planet, you are accomplishing something that the great astronomer Nicolaus Copernicus (who rediscovered the idea of a sun-centered solar system) supposedly never did.

To boot, the tiny planet is setting 2 hours after the Sun, which doesn't happen that often. 

Tuesday, May 5, 2015

Tonight's Sky for May 5-6:Delta Aquarid Meteor Shower Peaks


Tonight will mark the peak of the Eta Aquarid Meteor shower for 2015, thus marking the climax for the 2-week event. Every April and into May, Earth passes through the stretch of space junk shed by Comet Halley, reaching the deepest concentration of debris tonight. According to some estimates, under ideal conditions (dark country skies), one can expect to see 10-15 meteors per hour. The reason the meteors are called Eta Aquarids is because the meteors seem to radiate from the constellation Aquarius, namely the region of its eta star. The best time to view the shower is predawn, as Aquarius is at its highest (though still rather low in the Southern sky) then.

To improve odds of seeing meteors, travel out of the city and to the country if you can. In the suburbs, just going from the front to back yard can make a dramatic difference as this will eliminate glare from those pesky street/house lights to a large extent.

Unfortunately, this year's Eta Aquarid peak coincides with the Full Moon. The good news: even the Moon won't be able to drown-out the brightest meteors.

Sunday, May 3, 2015

Tonight's Sky for May 3: Full Moon

Tonight, the Moon will reach its full phase, which means that, as seen from Earth, it is directly opposite the Sun in the sky as seen from Earth and is at the half way point in its current orbit.


As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, when the Moon is opposite the Sun and on the far side of Earth, we can see all of its lit side, which is why it appears to be “full.” In the coming nights, we will start to see less of the Moon as its lit side starts to turn away from us as seen from Earth and heads toward Third Quarter. 

Saturday, May 2, 2015

Tonight's Sky for May 2: Venus Sets at Midnight


Venus is known as the 'Evening (or Morning) Star' for a reason: it is the brightest thing in the sky just after sunset or before sunrise. That explained, one can now appreciate how good of a show that Venus is putting on right now. Proof? Venus is now setting after midnight, which doesn't occur that often. So, with so much time visible after dark, make it a point to get out and view our nearest planetary neighbor.

Friday, May 1, 2015

The May Sky

With the arrival of May, the news is of a very mixed nature for astronomers in much of the USA. First, the bad. While the lengthening of the days will slow but that is little consolation for astronomers as, by this time of year, staying up for a dark sky often comes at the cost of being groggy for work in the morning. However, the good news is threefold. First, the rate of cloudiness will drop as it did last month. Second, May will finally bring consistently warm nights where bundling up is no longer a must. Third, at least at the start of the month, the bugs shouldn't be much of an issue, either.

Cool Constellations
By the time May arrives, most of the winter constellations are a memory. Still hanging around low in the West are Auriga and Gemini, but they won't last much longer. Also, barely circumpolar Cassiopeia is now just scraping the Northeastern horizon, too. By the time May comes around, there is no better time than now to use the handy Big Dipper signpost. Starting at the Dipper, follow the arc of the Dipper to bright orange Arcturus, alpha Bootes, and the brightest star in the spring sky. To the left of the kite-shaped Bootes, look for the arc of stars that is Corona, the crown. Next, speed onto blue Spica, alpha Virgo, and one of the brightest spring stars. Next, continue the curve to trapezoidal constellation Corvus, the crow. Finally, conclude in dim Crater the cup. Moving higher in the sky and looking in the South-Southwest, zodiac constellations Cancer and Leo are still well-placed, but this will be ending come next month. Speaking of Cancer, look just below the cosmic crab for a distinct ring of stars, the head of Hydra, the sky's biggest constellation, which snakes (sorry) through over 120 degrees of sky. For those who like to stay up later, there's mythological strongman Hercules and the Summer Triangle high overhead and, to the South, Ophiuchus, Serpens, Libra, and Scorpius are all starting to rise at a somewhat reasonable hour. By the time the sky starts to brighten, Vega is at Zenith, Sagittarius is due South, and the Great Square has reemerged in the East.

Planetary Perceptions
Like April, May is looking to be another 5 for 5 planet month, albeit with a couple of catches. The real treat for May, 2015 will be Mercury, which will be putting on its best evening show of the year this month, peaking in elevation around the 8th. Unfortunately, as is the norm with good appearances, once the little planet starts to drop, it will in short order disappear from the sky by 2 weeks after greatest elongation. Additionally, Mars, which has been hanging around low in the Southwest for the past several months, will finally drop out of visibility in May. On the other hand, Venus will continue to climb out of the dusk twilight all month long. Moving later into the night, Jupiter is well-placed for prime-time viewing as it rides high and due South at true nightfall. Additionally, Saturn continues to re-emerge from the Sun's glare in the predawn sky. By month's end, the ringed wonder will be in the Southwest at dawn.

Young Moon Season
Want to find the Holy Grail of naked-eye astronomy? Well, you're in luck as spring is Young Moon season, which runs through June and features wire-thin, barely there crescents just after sunset. The funny thing: many people who call Full Moons light pollution will plan young Moon hunts weeks in advance. So, why the change in attitude?

Young Moons are, besides quite aesthetic, rare, very rare. To sight a Young Moon under 24 hours old (and even one under 30 hours old), all the conditions need to line up just right. If everything goes perfectly, on the day after New Moon, or even on the same day sometimes, just past sunset, a wire-thin crescent will pop out low on the horizon among the Sun's last rays. Needless to say, when dealing with a Moon less than 2% illuminated, binoculars are a must.
So here is why the Young Moon is so difficult to spot:

1. Timing. If New Moon is timed too close to sunset, it will be lost in the Sun's glare on the day of New Moon and will be way past a day old come the next night. A 36 hour Moon is no challenge, pure and simple.

2. Clouds. If it's cloudy, there's no seeing the Moon.

3. Light. Young Moon hunters are forced to fight twilight. With the Moon only 1-2% lit, just the act of spotting the Moon low on the horizon in such light conditions is a challenge because that is where the Sun is. A saving grace can be (and was for me both times) a nearby planet, Mercury and Venus, respectively. If you can use a bright planet as a marker, it is a lot easier to estimate where the Moon will appear once the sky gets dark enough.

4. Haze. Even more so than during the day, haze makes its presence known at dusk, looking similar to wispy clouds on the horizon. While the biggest problem during the summer, haze can even appear in winter, too. Even a crystal-clear day can produce haze on the horizon at dusk. While the haze will quickly dissipate come dark, that's too late for the Young Moon.

These difficulties compounded with horizon issues showcase why Young Moons are the Holy Grail of Lunar observers. Now for the good news: spring is Young Moon season. Because of the near vertical ecliptic at sunset, the Young Moon will hang higher in the sky now than any other time of year, which is good. For Young Moon Hunters, March through May (even June depending on time of month) is an ideal time to look. By the time July rolls around, the ecliptic is undeniably flattening too much to make observing the Young Moon really feasible.
Get out while you can!

Future thin crescents:
May 18: 22 hour Moon
June 17: 36 hour Moon

The Big Dipper: Signpost to the Stars
Late spring and early summer presents the Big Dipper at its best just as the sky is getting dark. While many people not familiar with astronomy have heard of the Dipper, many people familiar with astronomy do not realize that it makes for a handy guide to the late spring/early summer sky. Starting at the Dipper, follow the arc of its handle to bright orange Arcturus, alpha Bootes and brightest star of the spring sky. From Arcturus and following the same line, speed on to Spica, Virgo's not quite as bright blue alpha star. From there, continue to Corvus, a small, though rather conspicuous trapezoid-like constellation low in the Southern sky and, from there, conclude in Crater, the dimmer, neighboring constellation to Corvus. Moving back to the Dipper, follow the imaginary line created by the stars representing the end of the bowl to Polaris, the North Star. Continuing that line about the same distance through the celestial pole will bring you to 'W'-shaped Cassiopeia, which is just scraping above the Northern horizon this time of year for us at mid-Northern latitudes. Besides aesthetic, the Dipper's pretty practical, isn't it?



Tonight's Sky for May 1: May (and Cross-Quarter) Day
Today is May Day and also a cross-quarter day. What is a cross-quarter day? It's the mid way point of any season and was, like the solstices and equinoxes, an important time for early civilizations as these days served as another natural way to divide up the year into periods of time, which became a matter of life and death with the advent of large scale agriculture around 5000BC.