Explanation: As its June 6 2012 transit begins Earth's sister planet crosses the edge of the Sun in this stunning view from the Hinode spacecraft. The timing of limb crossings during the rare transits was used historically to triangulate the distance to Venus and determine a value for the Earth-Sun distance called the astronomical unit. Still, modern space-based views like this one show the event against an evocative backdrop of the turbulent solar surface with prominences lofted above the Sun's edge by twisting magnetic fields. Remarkably, the thin ring of light seen surrounding the planet's dark silhouette is sunlight refracted by Venus' thick atmosphere.
This is a very interesting image. It gives Venus the appearance of nearly touching the sun. Even though I know it's much farther away, I can't seem to dispel the illusion. Then again, I can't get my craters to depress most of the time, either. The details in Venus's atmosphere are surprising.
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sat Jun 09, 2012 9:10 am
by rr_carroll
The thin ring of light seems several pixels across. Has anyone estimated the thickness which appears lit? I would guess it to be much less than the full depth of the atmosphere. In other words, we see a light band only above a certain altitude. Could this affect the spectrum in the band, presumably from different gases at high altitude?
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sat Jun 09, 2012 10:22 am
by Byork
truly fascinating
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sat Jun 09, 2012 11:49 am
by orin stepanek
Interesting story about Captain Cook and his crew and their fascination with the natives!
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sat Jun 09, 2012 12:25 pm
by Case
When I play with the brightness levels on this image, it seems like some atmospheric features are showing. Are these real, or am I imagining patterns in noise?
On my screen, the circle of Venus measures 108 mm high and 109 mm wide. Is the planet orb really that much flattened, or is it just an artifact of the image and/or rendering?
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sat Jun 09, 2012 9:00 pm
by Case
ecdowney wrote:On my screen, the circle of Venus measures 108 mm high and 109 mm wide. Is the planet orb really that much flattened, or is it just an artifact of the image and/or rendering?
I'd question your screen and your measuring method before anything else. My measurement is 546x546 px (quite a perfect circle) for Venus in todays picture.
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sun Jun 10, 2012 5:28 pm
by DavidLeodis
It is an exciting photo. Shame therefore that there is (well at least to me!) confusion as to when it was acquired. The explanation starts "As its June 6 2012 transit begins..." but in information brought up through links the photo is mostly stated to have been taken on June 5 (though to add to my confusion some also state June 6 as well as June 5 in information in the same link, such as through a link to the Hinode section in Flickr). From my understanding of the transit I would have said the photo was taken on June 5 under Universal Time but I'm now unsure.
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sun Jun 10, 2012 5:55 pm
by Chris Peterson
DavidLeodis wrote:It is an exciting photo. Shame therefore that there is (well at least to me!) confusion as to when it was acquired. The explanation starts "As its June 6 2012 transit begins..." but in information brought up through links the photo is mostly stated to have been taken on June 5 (though to add to my confusion some also state June 6 as well as June 5 in information in the same link, such as through a link to the Hinode section in Flickr). From my understanding of the transit I would have said the photo was taken on June 5 under Universal Time but I'm now unsure. :?
I'm sure you're correct. By Universal Time, the transit began on 5 June and ended on 6 June, with the majority occurring on 6 June. The position of the Hinode spacecraft only alters the apparent timing with respect ground-based observations by a few minutes. So this image had to have been made around UT 22:30 on 5 June, give or take a half-hour or so.
Re: APOD: Venus at the Edge (2012 Jun 09)
Posted: Sun Jun 10, 2012 6:57 pm
by DavidLeodis
Chris Peterson wrote:
DavidLeodis wrote:It is an exciting photo. Shame therefore that there is (well at least to me!) confusion as to when it was acquired. The explanation starts "As its June 6 2012 transit begins..." but in information brought up through links the photo is mostly stated to have been taken on June 5 (though to add to my confusion some also state June 6 as well as June 5 in information in the same link, such as through a link to the Hinode section in Flickr). From my understanding of the transit I would have said the photo was taken on June 5 under Universal Time but I'm now unsure.
I'm sure you're correct. By Universal Time, the transit began on 5 June and ended on 6 June, with the majority occurring on 6 June. The position of the Hinode spacecraft only alters the apparent timing with respect ground-based observations by a few minutes. So this image had to have been made around UT 22:30 on 5 June, give or take a half-hour or so.
Venus at the Edge
