When you want to see the stars, find someplace dark
Tomorrow morning, July 8th, Venus will pass less than 1° from Aldebaran. The Eye of the Bull may be one of the brightest stars in the sky at 0.9 magnitude, but it is no match for Venus at -4.4 magnitude.
On the morning of the 8th the planet will be 59′ from the star, just an iota under 1°. On the morning of the 9th the distance will be slightly closer at 55′. The pair will rise about 03:18, to be well up in the sky before sunrise.
Today Mercury reaches maximum elongation, the furthest point it will reach from the Sun in the sky and the highest it will be above the sunset this apparition. The planet is easily visible as a bright, starlike object about 15° above the setting Sun as the sky grows dark. Over the next couple weeks Mercury will slide back into the sunset, heading for inferior conjunction on Jul 28.
Saturn, the Moon and Spica will form a trio high in the sky at sunset tonight. The three will be within 7° of each other. The gibbous Moon will be 62% illuminated. Saturn will be shining at 0.4 magnitude while Spica is very close to 1.0 magnitude. Look for the planet Mars 25° west of Saturn at about the same brightness.
A very thin Moon will rendezvous with Mercury this evening. The pair will separated by about 8° and at the same elevation, over 20° at sunset. The Moon will be a very thin crescent, only 7% illuminated. A little over 5° north of Mercury will be Pollux, with Castor a bit further north, both stars about a magnitude dimmer than the planet which is currently about zero magnitude.
As Venus approaches maximum elongation it will pass through the Hyades star cluster. Because Venus reaches it maximum western excursion on July 1st the planet will sweep out an arc that runs just inside the V-shape of the cluster. Thus the planet will remain within the main body of the cluster for the next 20 days.
Today the planet is only 26′ from εTau at one corner of the V-shaped cluster. On July 8th the planet will pass about 1° from Aldebaran as it exits the cluster at the other corner of the V.
A nice trio will grace the dawn tomorrow, the morning of June 17th. Three bright objects will be visible just before sunrise. A brilliant Venus will be 14° above the horizon at sunrise. Above Venus will be a very thin crescent Moon, only 4% illuminated, will be 4° above Venus. About 8° above Venus will be Jupiter, shining brightly at -2.0 magnitude. Thus Jupiter will be the first to rise, at 04:02HST. Sunrise will occur about 05:43, leaving plenty of time to enjoy this bright conjunction.
This week Venus will appear in the dawn sky. Today the planet will be over 10° from the Sun at dawn. This will increase over a degree each day as Venus climbs higher into the dawn sky. Maximum elongation will occur on August 14th.
A few nice conjunctions will occur with both Jupiter and the Moon over the coming weeks. Stay tuned to Darker View for postings that will keep you up to date.
Black drop effect? Bah! I observed a beautiful aureole effect in the minutes leading up to second contact.
The famous black drop effect is seen when atmospheric distortion of the image is quite bad. The effect plagued the early observers attempting to do transit timings. The effect is not seen when the atmosphere allows sharp views of the transit.
Instead, if the seeing is truly good, it is possible to see something far more rare, the aureole of Venus. This is a faint ring of light that has been refracted and scattered through the atmosphere of the planet.
I had not expected to see this, the appearance of the arc of light a complete surprise. But there it was… Very thin, quite faint, a sharp arc of light completing the disk of Venus. The view was steady, with nearly perfect seeing the arc was visible continuously.
Analyzing the observation afterwards I realize it was two elements that allowed me to see the aureole, the excellent seeing offered by the summit of Mauna Kea and good equipment. I was looking through my TeleVue 76mm telescope, using an 8mm Radian eyepiece and a Baader solar film filter. Very good equipment indeed, the optical performance of the system was not going to be a problem.
In the confusion and effort of running the Keck Observatory web stream, I was so glad I managed to free up the few minutes necessary to properly observe second contact. The sight was one of the most beautiful and sublime of any I have witnessed through an eyepiece in my many years of looking through a telescope.
I have been through my photos, nothing captured the faint arc of the aureole, no matter how I stretch the exposure. The best I can do is to record a few drawings in my observing notebook, a poor substitute for the beauty of the real thing…
Transit is over, an exhausting and exhilarating day! I am headed to bed, but still totally jazzed with the experience. Keeping the webcast going for seven hours was a huge effort. Given the comments from our viewers it was worth it. I will have to more fully write up the experience for a later post.
The best visual for the day was the few minutes just before second contact… A beautiful, razor thin arc of light coming through the Venusian atmosphere, connecting the two horns of the occluded Sun. It was delicate and sublime, one of the most memorable sights I have ever seen through a telescope. With the excellent seeing of Mauna Kea, and the wonderful optics of my TV-76 telescope, the sight was clear and steady. I have yet to find a photograph that captures what I saw through the eyepiece.
I will post a quickly processed version of one of the frames from the second camera…
We will be webcasting the transit live from the Keck telescopes at the summit of Mauna Kea. Tune in for images of the transit, and a lot of information about the transit. Larry O’Hanlon and I will be talking about the transit, the science, the history, and just generally enjoying the experience. You are invited to join us. Expect the broadcast to start about 11:45HST, or about 25 minutes before first contact.
Want to see for yourself? There are multiple locations around the island where you will find solar telescopes and volunteer guides to answer your questions about this event. Not on the Big Island? Check you local paper or look up your local astronomy club to find public events. Science museums, colleges, astronomy clubs and other astronomy organizations are organizing public events wherever the transit can be seen.
| Location Name | External Sun Ingress Alt h m s ° |
Internal Sun Ingress Alt h m s ° |
Greatest Sun Transit Alt h m s ° |
Internal Sun Egress Alt h m s ° |
External Sun Egress Alt h m s ° |
| Anchorage, AK | 14:06:30 51 | 14:24:04 51 | 17:26:53 38 | 20:30:46 16 | 20:48:32 14 |
| Honolulu, HI | 12:10:07 85 | 12:27:46 89 | 15:26:20 49 | 18:26:38 9 | 18:44:38 5 |
| Kona, HI | 12:10:09 86 | 12:27:48 87 | 15:26:16 47 | 18:26:33 7 | 18:44:33 3 |
| Los Angeles, CA | 15:06:26 58 | 15:24:02 55 | 18:25:33 18 | — – | — – |
| Phoenix, AZ | 15:06:03 54 | 15:23:40 50 | 18:25:32 13 | — – | — – |
| Portland, OR | 15:06:05 57 | 15:23:40 54 | 18:25:53 23 | — – | — – |
| San Francisco, CA | 15:06:29 61 | 15:24:04 57 | 18:25:39 22 | — – | — – |
| Seattle, WA | 15:05:58 56 | 15:23:32 53 | 18:25:57 23 | — – | — – |
All times local. The data is taken from Fred Espenak’s NASA Eclipse Website. I extracted the cities that are of most interest to my Hawaiian readers. For the full list of US cities you can go here.
Please exercise caution when viewing the Sun! Use appropriate eye protection or indirect observing techniques to project an image of the Sun. The link at the start of this paragraph leads to a great discussion on viewing the Sun safely. As always the single best source on the web (or anywhere) for eclipse and transit information is Fred Espenak’s eclipse website at NASA. Stop by whenever you have a question on upcoming events as well as viewing and photography tips.