Tuesday, June 30, 2015

Tonight's Sky for June 30: Venus and Jupiter Are at Their Closest, 1/5th Degree Separation

Well, this is it: Venus and Jupiter, 2nd and 5th planets from the Sun and 3rd and 4th brightest objects in the sky, respectively, are only about 1/5th of an angular degree apart from each other. Needless to say, all but the most eagle-eyed observers will need some optical aid to be able to see the gap between the two. The good news: even a weak, 5x power pair of binoculars will easily to the trick. Also, for people who have a long zoom camera, be sure to take a picture as this is a planetary conjunction of historical significance

Monday, June 29, 2015

Tonight's Sky for June 29: Mercury at its Best

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. 

Saturday, June 27, 2015

Tonight's Sky for June 27: Venus and Jupiter Are Within a Degree of Each Other

Tonight, Venus and Jupiter, third and fourth brightest objects in the sky, are separated by about a single degree. For the record, they were about 5 angular degrees apart just about a week ago. As if 1 degree wasn't close enough, they'll get even closer, coming to within about 1/5th degree of each other. For more fun, take a picture if you have a long-zoom camera, it isn't hard to do! 

Friday, June 26, 2015

Tonight's Sky for June 26: The Latest Sunsets

While the solstice (and shortest nights) was almost a week ago week, the latest sunsets occur now. Why is this? Short answer: celestial mechanics. As for why the Sun doesn't have its extreme rise/set dates on the day of the solstice, it all has to do with solar noon, the point in time wherein the Sun reaches its highest point in the sky, which is the basis for the timing of the solstice. Problem: the Sun doesn't always reach its highest point in the sky as seen from Earth at noon. In addition, at the time of the solstice, the lay is actually longer than 24 hours. Result: solar noon doesn't always sync up with measured noon, hence why extreme sunrises and sets do not occur on the Solstices.  

Wednesday, June 24, 2015

Tonight's Sky for June 24: Mercury and Aldebaran

Just before sunrise, there will be a challenging cosmic sight that will require a good horizon and a pair of binoculars for all but the most eagle-eyed observers. Today just before dawn, speedy planet Mercury will be meeting Aldebaran, alpha Taurus, which is just reemerging from the Sun's glare after a period of invisibility. Top see the show, look just above the horizon in the East-Northeast sky. Mercury, the brighter object will be easier to see and will appear as white-yellow in color. Aldebaran, about 2 degrees below and right of the planet, will be harder to see and orange in color. If you see both bodies, be sure to congratulate yourself. 

Tuesday, June 23, 2015

Tonight's Sky for June 23: 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..

Monday, June 22, 2015

Tonight's Sky for June 22: Venus and Jupiter Separated by 5 Degrees

Tonight, Venus and Jupiter, third and fourth brightest objects in the sky, are separated by about 5 angular degrees, which is about half the distance they were from each other only about a week ago. Come month's end, they'll be within a degree of each other so, with a nice even number tonight, it may be a good time to begin the conjunction approach watch if you haven't already done so. For more fun, take a picture, it isn't hard to do! 

Sunday, June 21, 2015

Tonight's Sky for June 21: Summer Solstice

Today is the longest day of the year for us living in the Northern Hemisphere. With the summer solstice comes the longest day of the year and the official start of the summer season.
So, why do we have seasons, anyway?

It's all about Earth's tilt. If the Earth were spinning on its axis with no tilt at all, everyone would be treated to days of identical length every day of the year, with latitudes nearer the equator having longer days than those nearer the poles. However, with the tilt, the angle of the Earth relative to the Sun changes as or planet moves about its orbit. On the Winter Solstice (shortest day of the year) the Northern Hemisphere is tilted up and away from the Sun. On the Summer Solstice (today), the Northern Hemisphere will be tilted down toward the Sun. On the equinoxes, the tilt is half way between the solstices. To see this effect, go out and observe the path the Sun takes through the sky for the course of day of winter).

Saturday, June 20, 2015

Tonight's Sky for June 20: Venus, Jupiter, and the Moon at Dusk

Tonight just after dusk, the Moon, Venus, and Jupiter, 2nd, 3rd, and 4th brightest objects in the sky, respectively, will all be within 10 degrees of each other. To simulate the angular gap, just hold your clenched fist out at arm's length. While not the closest of conjunctions possible, this still makes for a pretty neat, easy to see grouping. Also of note, notice how Venus and Jupiter are getting ever closer . . .

Friday, June 19, 2015

Tonight's Sky for June 19: The Moon is Directly Below Venus

Tonight just after dusk is a celestial meet-up that couldn't have been drawn better as the Moon will be directly, and I mean directly, below Venus, second planet from the Sun and 3rd brightest object in the sky behind the Sun and Moon. 

Thursday, June 18, 2015

Tonight's Sky for June 18: Jupiter Sets 4 Hours After the Sun

Tonight, Jupiter, fifth planet from the Sun and largest planet in the solar system will be setting four hours after the Sun. To see Jupiter this evening, go out just after the sky starts to dim in the evening and look West-Southwest. If it is clear, you will see a bright yellow 'star' that, is in fact, the planet. Oh, yes, Venus is nearby, too, which means that Jupiter is the second brightest star.

To aid in one's planet hunting, a pair of binoculars is a good idea as, while the planets are rather bright, you will be fighting the brightening sky, which can make finding them difficult.

Wednesday, June 17, 2015

Tonight's Sky for June 17: Young Moon

How thin of a Moon have you seen? How about one that's less than 2 days 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 Western horizon. How good? One with less than 10 degrees of obstruction. To simulate this, hold a fist vertically at arm's length to simulate 10 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, head there about 45 minutes after 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.  

Tuesday, June 9, 2015

Tonight's Sky for June 9: Last Chance for Gemini

There are many harbingers of the seasons: first flower, falling leaves, first snow, and more holidays and events than one can probably even think of. Well, here's another one: Gemini standing up straight relative to the horizon at dusk in early June, which means that summer's on the way and school's about to be (or already is) out for the season.

Sunday, June 7, 2015

Tonight's Sky for June 6: Can You See Capella Yet?

Yesterday's feature was jumping forward a few weeks to summer. Today's is jumping forward a several months to winter. Just before sunrise, look low in the Northeast for a 0-magnitude, yellow star that is Capella, alpha Auriga, and the first visible star of the Winter Hexagon.

Friday, June 5, 2015

Tonight's Sky for June 5: The Summer Triangle Now Up Within Hour of Sunset

Summer may technically a few weeks in the future but don't tell that to the stars. Within an hour of the Sun setting in the West, the Summer Triangle, an asterism of 0 and +1 magnitude stars from three different constellations that also happen to be among the brightest of any season, will be up above the horizon. 

Thursday, June 4, 2015

Tonight's Sky for June 4: Venus and Jupiter Separated by 20 Degrees

Tonight, Venus and Jupiter, third and fourth brightest objects in the sky, are separated by about 20 angular degrees. Come month's end, they'll be within a degree of each other so, with a nice even number tonight, it may be a good time to begin the conjunction approach watch. For more fun, take a picture, it isn't hard to do

Wednesday, June 3, 2015

Tonight's Sky for June 3: Venus Lines Up With Castor and Pollux

Tonight at dusk, Venus, Castor, and Pollux will form an almost perfect straight line in the Western sky at dusk. To see the show, head out after the sky starts to dim and look West. Venus, third brightest object in the sky only behind the Sun and Moon, will be impossible to miss. As for Pollux and Castor, they're a pair of bright stars and as well as alpha and beta stars of the zodiac constellation Gemini. If the fact that the line is just about straight weren't unique enough, The stars and planets are all separated by about the same angular measurement, too. 

Tuesday, June 2, 2015

Tonight's Sky for June 2: 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.

Monday, June 1, 2015

The June Sky

The arrival of June also heralds the first day of summer and thus, the Summer Solstice, the longest day of the year. Since the length of day/night varies with latitude (the more North you go, the more extreme the lighting), not all people will be having equal length nights on the longest day of the year. For us in the United States, we will have about 8-9 hours from sunset to sunrise. When considering the fact that the transition to true dark consumes about 1 ½ hours on each end of the night, when all is said and done, people living in the Northern Continental U.S. may only have about 5 hours of dark sky observing in June (it never gets truly dark in much of Alaska this time of year). Now the good news: the summer sky is a cosmic picture book.

Cool Constellations
By the time June arrives, some of the Spring constellations are already taking their annual dives out of view. Among these are Corvus, Crater, Hydra, Cancer, and, to a lesser extent, Leo. By the arrival of June, the Big Dipper signpost is starting to become obsolete. As the Dipper begins its annual dive, on the other end of the arc,Corvus and Crater are already disappearing but Bootes and Virgo are coming into their best placements of the year. By the time July comes, you'll only be able to speed on to Spica.
Besides the already mentioned herdsman and virgin, Corona, Hercules, the Summer Triangle (made up of constellations Lyra, Cygnus, and Aquila), Ophiuchus, and Serpens are all flying high at this time of year, too. For those who like to stay up later, Libra and Scorpius are also on the rise, as is deep sky treasure trove Sagittarius along with the ghostly arch across the sky that is the Milky Way. By the time the sky starts to brighten, a fall preview in the form of Pegasus, Andromeda, Aries, Capricorn, Aquarius, and even Pisces Australis is on tap, too.

Planetary Perceptions
Unlike the past few months, June is looking to be a pretty rotten month for watching planets as Mercury and Mars are really non-issues with the former making a quick, anything but impressive appearance in the morning sky come late month and the latter being lost in the Sun's glare all month long. More bad news: June also presents the last real chance to catch Jupiter under a truly dark sky as twilight begins to catch up to the planetary king by months end. That said, the The real treats for June will be Venus and Saturn. Making the origin of its nickname of 'the Evening Star' very evident, Venus shines brightly just after sunset in the Western sky before it too begins to plunge starting mid month. As an item of note, there will be a very close conjunction of Venus and Jupiter on the 30th. At minimal separation, the planets are only separated by about 1/5th angular degree. Moving into the night, Saturn, is well-placed for prime-time (though 'prime-time' is now rather late) observing as it is just about due South at the onset of true night.

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 June 1: Venus Sets 3 ½ Hours After the Sun
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 about 3 ½ after the Sun which, this time of year, puts its set time past 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.