by Joe Stieber » Wed Jan 05, 2011 5:00 pm
Redstone wrote:I am looking at that picture, and I'm thinking y smart people of the APOTD can be making a mistake this grossly bad!
This does not to me look like the ISS crosing the disk of the sun. it looks like Hubble that is in transit! Yes?
it' far too small and not complex enough for ISS, yet the profile matches Hubble perfectly!
Having seen the ISS transit the sun and the moon visually through a telescope a number of times, as well as having seen the ISS visually through a telescope in the open sky a number of times, I can also add that today's APOD does indeed show the ISS, not the HST.
The profile does
not match the HST, which has relatively small solar panels compared to the body of the spacecraft, as shown here:
http://en.wikipedia.org/wiki/Hubble_Space_Telescope
In contrast, the ISS has relatively large banks of solar panels as shown here:
http://en.wikipedia.org/wiki/Internatio ... ce_Station
The apparent size of the ISS can vary considerably since it is currently about 350 km away when it crosses the zenith, but over 2,000 km away near the horizon. It was around 45 degrees altitude when the image was captured. Regardless, based on the 109 m length of the truss from Wikipedia and the 510 km distance reported on Legault's web page, the ISS should subtend about 0.74 arc-minutes in the picture. Measuring the image on my computer screen, it was about 4.5 mm along the truss of the ISS and 190 mm across the sun. Using a solar diameter of 32.5 arc-minutes for January 4th (from USNO software), my crude screen measurements yield a similar 0.77 arc-minutes for the ISS.
Joe Stieber
[quote="Redstone"]I am looking at that picture, and I'm thinking y smart people of the APOTD can be making a mistake this grossly bad!
This does not to me look like the ISS crosing the disk of the sun. it looks like Hubble that is in transit! Yes?
it' far too small and not complex enough for ISS, yet the profile matches Hubble perfectly![/quote]
Having seen the ISS transit the sun and the moon visually through a telescope a number of times, as well as having seen the ISS visually through a telescope in the open sky a number of times, I can also add that today's APOD does indeed show the ISS, not the HST.
The profile does [b][i]not[/i][/b] match the HST, which has relatively small solar panels compared to the body of the spacecraft, as shown here:
http://en.wikipedia.org/wiki/Hubble_Space_Telescope
In contrast, the ISS has relatively large banks of solar panels as shown here:
http://en.wikipedia.org/wiki/International_Space_Station
The apparent size of the ISS can vary considerably since it is currently about 350 km away when it crosses the zenith, but over 2,000 km away near the horizon. It was around 45 degrees altitude when the image was captured. Regardless, based on the 109 m length of the truss from Wikipedia and the 510 km distance reported on Legault's web page, the ISS should subtend about 0.74 arc-minutes in the picture. Measuring the image on my computer screen, it was about 4.5 mm along the truss of the ISS and 190 mm across the sun. Using a solar diameter of 32.5 arc-minutes for January 4th (from USNO software), my crude screen measurements yield a similar 0.77 arc-minutes for the ISS.
Joe Stieber