* Astronomy

Blobrana · L

RE: Transit of Venus 2012

Blobrana · L

Blobrana · L

Gestatten: die Venus, 9 Stunden vor dem Transit

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Ed ~ Incredible image capture (I tried two days ago and failed)

Blobrana · L

Title: Solar diameter with 2012 Venus transit: history and opportunities
Authors: Costantino Sigismondi

The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides. Fruitful observations can be obtained also by amateur astronomers, by following the instructions in this paper. All ground-based observations designed to achieve this goal are warmly welcome to be analysed by the author, presently visiting the Huairou Solar Station of National Observatories of China for observing that transit. Finally a minimal observational schedule is suggested.

Read more (155kb, PDF)

Blobrana · L

Venus transit: A last-minute guide

We've had dozens of stories about Venus' day in the sun over the past few weeks, but for those of you who are just tuning in, here are the top 10 things to keep in mind about today's transit, whether your skies are sunny or completely socked in: Read more

Ed ~ To find out what you can see when, use the U.S. Naval Observatory's transit computer.

eg Aberdeen

                 Location:  W  2°10'00.0", N57°15'00.0",     0m                  
                    (Longitude referred to Greenwich meridian)                     
     
                                                   Sun's          Position   Angular
                                UT1         Altitude   Azimuth     Angle    Separation
                            d  h  m   s         °          °          °          '
Sunrise                     6 03:16           ----       42.7      -----       ----
Egress Interior Contact     6 04:36:59.7       7.6       59.3      291.1       15.3
Transit Ends                6 04:54:31.3       9.7       62.8      288.7       16.2
     
                 Duration:    1h 38m 07.0s
       Solar Semidiameter:   15' 45.7"
    Semidiameter of Venus:    0' 28.9"

Blobrana · L

The transit of Venus begins at 22:02:25 UT, 5th June, 2012.

The Transit of Venus ends at 04:56:39 UT, 6th June, 2012.

Blobrana · L

June 2012 Transit of Venus

At sunrise on the 6th of June 2012 in the UK, the planet Venus will be seen in transit across the disk of the Sun. The transit can be observed with the naked eye but you must wear proper eye-protection - either so-called 'eclipse glasses' or dense welding goggles. Do not be tempted to view the sun through thin cloud either with the naked eye or any form of optical aid.

Please note: contrary to much published advice, we do not recommend the eyepiece projection method of viewing the sun as a great many modern instruments employ plastics extensively in their construction and the heat from the focused solar image will destroy parts of these telescopes - only use the projection method if you are confident that your telescope is of all-metal construction. (in the USA the transit is visible late in the afternoon of the 5th of June 2012). Presented by Robert J Dalby FRAS

Blobrana · L

Transit of Venus - Last in a Lifetime

06 June 2012, 04:20 - 05:45
Venue: University Library, Aberdeen
Speaker: James Reid / Ken Skeldon

In Aberdeen, we're lucky to just be able to see the transit, as it happens so close to dawn. For approximately an hour, just after sunrise at 4.30am, Venus will be seen moving across the Sun's disc showing itself as a slowly moving dark spot about a 1/30th the diameter of the rising sun.
Aberdeen Astronomical Society will be viewing the Transit from various locations and taking photographs and measurements.
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Blobrana · L

ISS Transit of Venus

High above Earth, astronaut Don Pettit is about to become the first human to witness and photograph a transit of Venus from space. His images and commentary will be streamed to Earth during the crossing.

Blobrana · L

Transit of Venus: What is it and why is it so rare?

The transit of Venus, where the planet Venus passes directly between the Earth and the Sun, will begin at 2204GMT on Tuesday 5 June and will end at 0455GMT.
Here, science presenter Liz Bonnin explains how the transit works and why it is such a rare event - the next one will not happen until 2117.
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