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Sky notes for July 2012
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03-07-2012 2:13pm#1hi all,
sorry about the delay on these ... things got a bit manic the last while! I also missed posting the June notes as I was in the US for the May 20th annular eclipse (great view of the event from near Mt. Shasta, in northern California) and caught the transit of Venus too --it was the evening of June 5th from my location at 32,000 feet in an aircraft that had departed Atlanta airport a half hour earlier
All times are given in Summer Time
Skylight for July 2012
This month's highlight requires an early rise on the morning of July 15th to spy Jupiter extremely close to the northern limb of the waning crescent Moon. The sight will be spectacular as the planet skims just above the pockmarked lunar surface. The pair will be closest around 3am when they are just over two arc-minutes apart and easily fit in a low-power eyepiece field of view.
Jupiter will be grazed by the Moon from mid- to southern England (where the planet's disk is partly hidden by the Moon) and completely occulted from the southeast part of the UK and
Europe. It's just a near-miss from Ireland but still no less spectacular.
Observers with cameras or web cams hooked up to their telescope (or even a good telephoto lens) should try capture a number of images taken at equal intervals that can then be combined into a sequence showing the event.
Even binoculars will suffice to glimpse the four largest Jovian moons arrayed either side of their parent planet as our Moon glides by. Add the fact Jupiter sits between the beautiful Hyades and Pleiades star clusters this month -- with the nearby presence of Venus also complementing the scene -- then the sight before dawn mid-month should be breathtaking.
Oh, and it all takes place on a Sunday morning so there's no excuse not to be up! It will make that long lie-in after a successful observing session all that bit more rewarding.
Finally, a rare opportunity to see the Chinese space station Tiangong-1 from our latitude also falls on the morning of July 15th. This is the only pass in our skies at the moment and I know of no sighting so far from Ireland. The station's orbit carries it only 10 degrees above the horizon from here so do try adding a sighting of this new celestial outpost to your observing log. Check http://www.heavens-above.com for predictions for your location.
The Sun
There was a dearth of large sunspot groups over the past month or so but this is not any cause for suspecting something is wrong with our Sun -- solar maximum is still predicted to be in early 2013, albeit a much less active one than that previous. You can check the latest prediction summary at http://solarscience.msfc.nasa.gov/predict.shtml
Earth is at aphelion, or furthest from the Sun, on July 5th at 5am when we are 3.4% more distant from our parent star than in early January. The Earth's slightly elliptical orbit isn't the cause of our seasons, but our planet's axial tilt.
The Moon
Full Moon is on July 3rd, Last Quarter Moon on the 11th, New Moon on the 19th, and First Quarter on the 26th. Ramadan commences on July 20th but is generally determined by the first sighting of the lunar crescent after New Moon.
July's Full Moon is commonly called the Buck Moon by some Native American Indian tribes. This is because July is the month the new antlers of buck deer start to grow. I was reminded of this when in Glendalough recently and on our stroll we came across a beautiful young deer peacefully grazing. It stood not 5 metres from where we stopped and was oblivious to our presence. I often think amateur astronomy makes us more tuned to many other wonders around us and lifts the soul on encountering such unexpected and delightful sights.
The Planets
Mercury is at greatest eastern elongation on July 1st but is quite low in the evening twilight so the only real chance of spotting it are the first few days of the month, if at all. Observation will be a tad more difficult as the planet will only be magnitude +0.6 around this time. Carefully scan above the west-northwest skyline with binoculars after sunset to see if you can spot the planet's spark. Mercury then slides back into the solar glare after the first week of July and passes through inferior conjunction on the 28th.
Mars and Saturn can both be found above the southwest horizon in Virgo as the evening twilight deepens. Mars is moving eastward and closes in but does not quite catch Saturn during the month. Both Mars and Saturn will set just before midnight by July 31st. The Moon lies near the two on the evenings of July 24th and 25th.
The Red Planet crosses the celestial equator from north to south on July 5th and declines in brightness from magnitude +0.9 to +1.1 during the month as the distance from Earth grows. The disk of Mars is quite small now and appears just 6 arc-seconds across. Some general detail will be made out in larger telescopes.
The northern aspect of Saturn’s ring system is tipped 13 degrees towards us during July. On the 15th the planet is at quadrature, or 90 degrees east of the Sun. This is a wonderful opportunity to see the shadow of the globe projected onto the rings, giving a nice 3-D effect to the view in a telescope. Contrast the yellowish tint of Saturn with the bluish light of Spica, brightest star in Virgo, on the morning of July 1st when the pair are 5 degrees apart and of similar brightness.
Venus and Jupiter are morning sky objects in the constellation Taurus rising ahead of the Sun. Venus is brightest on July 10th (magnitude -4.5) but reaches its greatest illuminated extent on the 12th -- this is where the illuminated fraction of the planet's disk covers the greatest area of sky. A more detailed explanation of the term can be found at http://earthsky.org (look for the section on tonight’s sky and skip to July 12th’s notes).
Venus starts the month quite low before dawn but gains in altitude over the period. It will rise more than two and a half hours before the sun by the end of the month. The planet shows a slender crescent in a small telescope at the beginning of July that is 17% sunlit with the phase changing to be 44% lit by the 31st. Look for Venus within 1 degree of the red star Aldebaran on the morning of July 9th or an even more dramatic sight on the 11th when Venus, Aldebaran, and Jupiter all fit within a 6 degree circle.
Jupiter sits between the Pleiades and Hyades star clusters this month (being closer to the latter) and this month’s highlight covers the near-miss between the Moon and Jupiter on the 15th.
Comets
No bright comets are visible this month.
Meteors
The Southern Delta Aquarids peak with a ZHR of 16 or so meteors around the 29th. The radiant, or point of origin of the meteors, rises at around 02h. There is a waxing gibbous moon around but it will set at the same time the radiant appears above the horizon, allowing for a couple of hours of observing before dawn.
Details of additional minor meteor showers during July can be found at http://meteorshowersonline.com/calendar.html or http://www.imo.net/calendar/2012
* ZHR, or Zenithal Hourly Rate, is a theoretical value. It is based on the assumption the radiant source is overhead, you are observing from a dark site under a completely clear sky with no Moonlight interference, and no meteors are missed by the observer. The actual number of meteors seen is always much lower.
Asteroids
Taurus seems to be a major solar system crossroads this month as the paths of Ceres and Vesta also wind their way through the constellation along with those of Venus, Jupiter and the Moon. Both asteroids are not at their potential brightest but can be spotted with some patience. Venus shines at magnitude +8.4 while Ceres is a little fainter at magnitude +9.1 -- later in July might be the best time to hunt for the pair as they will then be in a darker sky before dawn. You can get finder charts at http://www.rasnz.org.nz/Asteroids2012.htm but you will need to turn them round to suit your view as they are orientated for southern hemisphere observers.
Spaceflight
The next ISS Expedition crew is scheduled to launch on July 14th or 15th on a Soyuz rocket from Baikonur Cosmodrome in Kazakhstan.
The third unmanned H-2 Transfer Vehicle (HTV) is scheduled to launch around July 20th. This is the Japanese ISS resupply spacecraft which is capable of carrying 6 tonnes of payload into orbit. The HTV does not automatically dock with the ISS but instead manoeuvres close to the station before being grabbed by the robotic arm Canadarm-2 and berthed to the Harmony module.
See http://en.wikipedia.org/wiki/2012_in_spaceflight and also the Planetary Society blog at http://www.planetary.org/blogs/emily-lakdawalla/ after the start of each month for updates on the status of unmanned missions across the solar system.
Out and about
Dublin is the 2012 European City of Science and http://www.dublinscience2012.ie/ lists details of numerous events around the City during July to celebrate the occasion.
See http://www.science.ie for details of other activities which are happening countrywide
July 4th: Knocklyon native Fergal Mullally, who is Science Officer at the NASA Ames Research Center in California, will give a presentation in the Science Gallery at TCD on NASA's ground-breaking Kepler mission. He will talk a little about the Kepler spacecraft, how we find extrasolar planets, and present some of recent exciting planet discoveries. You can book for this free talk at http://sciencegallery.com/event
July 5th (to 14th): The inaugural UCD Imagine Science Film Festival will take place in Dublin from Thursday 5 July – Saturday 14 July. This innovative project was developed by UCD in collaboration with the Imagine Science Film Festival New York. Throughout the festival Dublin will host some of the world’s most celebrated scientists, filmmakers and critical thinkers. See http://www.ucdimaginescience.ie/ for more details.
July 12th: Brian Greene is a professor of physics and mathematics at Columbia University, and is recognised for a number of groundbreaking discoveries in his field of superstring theory. As part of the Science Foundation Ireland speaker series, Professor Greene will give a talk at TCD's Science Gallery in Pearse Street. See http://sciencegallery.com/events
July 11th to 15th: Dublin will host the Euroscience Open Forum (ESOF) from the 11-15 July, 2012 in the National Conference Centre. ESOF is an interdisciplinary, pan-European meeting, held under the auspices of Euroscience, which aims to present the latest developments in science and technology, foster a dialogue on the role of science and technology in society and public policy, and stimulate public awareness of, and interest in, science and technology.
July 15th: The first Robert Boyle Summer School will take place in Lismore, Co. Waterford this July. It is a celebration of the life, works and legacy of Robert Boyle, the “Father of Modern Chemistry” and native of Lismore. The school will start on 15 July with an evening BBQ and continues over four days with talks, walks and discussions. This year is particularly significant as it’s the 350th anniversary of “Boyle’s Law”. See http://www.robertboyle.ie/ for more information.
Exploring further
The following web sites are also a great resource for information about what’s on view in our skies during the month;
http://www.skymaps.com — superb charts you can download
http://www.jb.man.ac.uk/astronomy/nightsky/
http://www.guardian.co.uk/science/series/starwatch
http://www.telegraph.co.uk/news/newstopics/nightsky/
http://www.heavens-above.com — space station predictions
http://dcford.org.uk/index.php -- the Digital Astrolabe
http://earthsky.org/astronomy-essentials -- absolutely essential reading for what's up
http://www.jodcast.net — monthly night sky tour for MP3 players
http://www.spaceweather.com – details of transitory events during the month as well as aurora alerts
http://spaceflightnow.com — mission launches and other news (click “Launch Schedule” too)
http://www.skymania.com – astronomy and space news
http://www.universetoday.com – more astronomy and space news
http://www.nightskyobserver.com/the-sky-this-month.php -- Gary Nugent’s astronomy and space news
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Just to clarify it is on the 12th and not the 14th like you said yeah?
Many thanks for pointing out the error shizz ... I was typing up some of the material after midnight so sleep was beckoning at that stage
I have the correct date of the 12th added above now. Must book a place myself for the talk.
John0
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