The Sky This Week : June 17 – 24, 2014 !

The Sky This Week, 2014 June 17 – 24

Celestial sights for the shortest nights.
The summer Milky Way from Cassiopeia to Sagittarius
imaged from Morattico, Virginia

The Moon spends the week wandering through the star-poor constellations in the early morning sky.  Last Quarter occurs on the 19th at 2:39 pm Eastern Daylight Time.  Luna won’t encounter any bright objects until the pre-dawn hours of the 24th, when her waning crescent will be just over two degrees to the south of bright Venus in the gathering morning twilight.

This week we experience the shortest nights of the year as we mark the summer solstice at 6:51 am EDT on the 21st.  At this time the center of Old Sol’s disc stands directly above the Tropic of Cancer over the border between Libya and Chad on the African continent.  Here in Washington we will experience 14 hours 54 minutes of daylight for most of the week before the length of day begins to slowly recede.  Thanks to our planet’s elliptical orbit our latest sunset won’t occur until the 28th.

You’ll have to stay up pretty late in order to take advantage of the Moonless skies around the time of the solstice.  Even though the Sun sets at around 8:37 pm the end of evening astronomical twilight doesn’t occur until two hours later.  However, it’s worth your while to wait for darkness if you happen to be in a good dark location well away from city lights.  Summer is the season to enjoy the panoply of the brightest stretches of the Milky Way, our home galaxy, which arches across the sky during the darkest hours.  By 1:00 am the densest part of the galaxy straddles the southern horizon as we peer toward its core some 30,000 light-years away in the direction of the constellation of Sagittarius.  The galactic center itself is hidden from our direct view by dense clouds of stars and associated star-stuff.  While they cloak the Milky Way’s core with mystery, they are wonderful targets for binoculars and small telescopes.  I have spent many hours in a beach chair poking around these star-filled regions with a simple pair of binoculars marveling at the vast numbers of faint stars that form the galaxy’s soft glow along with the bright knots of star clusters and faintly glowing gas clouds known as “nebulae”.  On very clear nights it is also interesting to look at the spaces where the stars appear absent.  These “dark nebulae” are actually cold clouds of gas and dust that contain the building blocks of new stars, planets, and even life forms.  Exploring the Milky Way is always a highlight of my summer vacation.

The early summer evenings are still dominated by the glimmer of three bright planets, but one of them is rapidly leaving us.  Giant Jupiter, which has dominated the night sky since the beginning of the year, is now just weeks away from conjunction with the Sun.  Old Jove still shines brightly in the west as twilight deepens, but he now sets just after 10:00 pm.  He still shines at a bright -1.8 magnitude, and he seems to be bidding me farewell when I set my telescope up in the front yard, shining through a gap between the houses across the street.  About all I can see of him now is his undulating disc and the fuzzy blobs of his four bright Galilean moons.

Mars is also a bright object that’s hard to miss.  You’ll find the red planet in the southwestern sky as twilight deepens and ends, betrayed by his distinctive ruddy hue.  Mars is picking up speed as he wends his way eastward along the ecliptic and closes in on the bright blue star Spica.  Once he passes the star in another couple of weeks he will begin a rapid dash along the ecliptic in a race with the encroaching Sun.  He’ll pay a call on many of the bright stars of summer as he lingers in the southwest for the rest of the year.

Saturn is now the planet of choice for the small telescope owner.  He transits the meridian just after 10:00 pm, so he’s well-placed for viewing during “prime-time”.  Saturn’s rings are now generously tipped toward our line of sight, and a telescope of four inches or more aperture will show the dark gap known as Cassini’s Division that separates the outermost ring from the brighter inner one.  This division is an actual gap that’s about as wide as the diameter of Mars; it is caused by a gravitational resonance with the innermost of Saturn’s larger moons.  Any telescope should show the planet’s brightest moon Titan, but you’ll need six or more inches to spy many of the smaller ones.

Venus gets a visit from the thin crescent Moon by the week’s end.  For the next couple of month she will rise at the beginning of morning twilight, so you will have to seek her in a brightening sky.  Fortunately she stands out quite well under these conditions, so you shouldn’t have any trouble spotting her other than waking up before sunrise!


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