APOD: A Double Eclipse of the Sun (2015 Mar 22)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4038
Joined: Fri Dec 04, 2009 3:27 am

APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by APOD Robot » Sun Mar 22, 2015 4:06 am

Image A Double Eclipse of the Sun

Explanation: Can the Sun be eclipsed twice at the same time? Last Friday was noteworthy because part of the Earth was treated to a rare total eclipse of the Sun. But also on Friday, from a part of the Earth that only saw part of the Sun eclipsed, a second object appeared simultaneously in front of the Sun: the Earth-orbiting International Space Station. Although space station eclipses are very quick -- in this case only 0.6 seconds, they are not so rare. Capturing this composite image took a lot of planning and a little luck, as the photographer had to dodge a series of third objects that kept, annoyingly, also lining up in front of the Sun: clouds. The above superposed time-lapse sequence was taken from Fregenal de la Sierra in southern Spain. The dark disk of the Moon dominates the lower right, while the Sun's textured surface shows several filaments and, over an edge, a prominence.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

User avatar
Nitpicker
Inverse Square
Posts: 2690
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Nitpicker » Sun Mar 22, 2015 4:20 am

Mister Legault has produced a number of amazing ISS transit images over the years. This is another. Makes me wonder if the people aboard the ISS had a chance to view the eclipse at all, however briefly? Do they even have windows pointing away from the Earth?

User avatar
bystander
Apathetic Retiree
Posts: 20252
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by bystander » Sun Mar 22, 2015 4:59 am

Nitpicker wrote:
Mister Legault has produced a number of amazing ISS transit images over the years. This is another. Makes me wonder if the people aboard the ISS had a chance to view the eclipse at all, however briefly? Do they even have windows pointing away from the Earth?

Solar Eclipse From the International Space Station

Expedition 43 Flight Engineer Samantha Cristoforetti took a series of photographs of the March 20, 2015 solar eclipse from the International Space Station. Cristoforetti wrote, "Orbital sunrise and the #SolarEclipse... could it go any better?" ...
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
Nitpicker
Inverse Square
Posts: 2690
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Nitpicker » Sun Mar 22, 2015 6:21 am

Thanks bystander.

Guest

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Guest » Sun Mar 22, 2015 7:25 am

I'm having a difficult time proving this alignment happened. Where was ISS Mar 20 2015 9:20 UT?

Boomer12k
:---[===] *
Posts: 2691
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Boomer12k » Sun Mar 22, 2015 8:52 am

I don't call a transit an eclipse.... When Venus transits the Sun, we don't say eclipse.....

I would say a transit, and eclipse.... Eclipse is a more vast blocking of the object..... Occultation, would also be an eclipse.... But it is the total blockage from view....and we don't say, eclipse...

Still a great and interesting photo...
:---[===] *

eaglekepr
Ensign
Posts: 13
Joined: Thu Jan 06, 2011 11:32 pm

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by eaglekepr » Sun Mar 22, 2015 9:21 am

Guest wrote:I'm having a difficult time proving this alignment happened. Where was ISS Mar 20 2015 9:20 UT?
Somewhere other than this photo. Using Stellarium and the location given, these photos were taken at 09:06:13/14 UTC. All three objects were aligned to match Mr. Legault's result.

Image

User avatar
Nitpicker
Inverse Square
Posts: 2690
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Nitpicker » Sun Mar 22, 2015 11:06 am

Guest wrote:I'm having a difficult time proving this alignment happened. Where was ISS Mar 20 2015 9:20 UT?
The ISS is directly above the Earth (and the Sun and the Moon) at all times. :wink:

According to Mr Legault's page (available from the APOD caption) -- http://www.astrophoto.fr/eclipse-iss-20150320.html -- the transit happened at 09:05:04 UT. The timing can be quite sensitive to observation location on Earth (and also the ISS boost schedule, see: https://www.heavens-above.com/IssHeight.aspx).

User avatar
Nitpicker
Inverse Square
Posts: 2690
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Nitpicker » Sun Mar 22, 2015 1:29 pm

Boomer12k wrote:I don't call a transit an eclipse.... When Venus transits the Sun, we don't say eclipse.....

I would say a transit, and eclipse.... Eclipse is a more vast blocking of the object..... Occultation, would also be an eclipse.... But it is the total blockage from view....and we don't say, eclipse...

Still a great and interesting photo...
:---[===] *
Maybe a transit and two eclipses? The ISS transits across the face of the partially visible Sun, but is also eclipsed as it passes through the Moon's shadow.

songwriterz
Ensign
Posts: 17
Joined: Fri Nov 04, 2005 1:18 pm

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by songwriterz » Sun Mar 22, 2015 1:35 pm

Looks more like the TIE fighter vanguard of an Imperial invasion to me.

Tszabeau

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Tszabeau » Sun Mar 22, 2015 2:28 pm

Ssshhhh... the Moon is catching some zzzzzzzzzs.

jalfano

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by jalfano » Sun Mar 22, 2015 4:21 pm

Thank you to the writers for the link to the word "clouds" - the Joni Mitchell video (Both Sides Now, live 1970) was extremely nice.

ta152h0
Schooled
Posts: 1373
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by ta152h0 » Sun Mar 22, 2015 6:05 pm

there is an equally powerful " advice " in the form of music , by Phil Collins, " Both Sides of the Story "
Wolf Kotenberg

Guest

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Guest » Sun Mar 22, 2015 10:22 pm

Why do the ISS images not line up?

User avatar
Nitpicker
Inverse Square
Posts: 2690
Joined: Fri Sep 20, 2013 2:39 am
Location: S27 E153

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Nitpicker » Sun Mar 22, 2015 11:21 pm

Guest wrote:Why do the ISS images not line up?
Line up with what?

User avatar
Chris Peterson
Abominable Snowman
Posts: 15248
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Chris Peterson » Mon Mar 23, 2015 12:30 am

Guest wrote:Why do the ISS images not line up?
Are you suggesting that the path of the ISS isn't straight? If so, you're probably seeing some kind of optical illusion based on all the different shapes. When I load the image in Photoshop and draw a ruler line along the path, no ISS image deviates from that line by more than a pixel or two, which is easily explained by typical daytime seeing distortion.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Ludo

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Ludo » Mon Mar 23, 2015 6:42 pm

More interestingly for me, I'd like to see more photos from the ISS looking at Earth during the eclipse..

ta152h0
Schooled
Posts: 1373
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by ta152h0 » Mon Mar 23, 2015 6:47 pm

and comets
Wolf Kotenberg

User avatar
geckzilla
Ocular Digitator
Posts: 9101
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by geckzilla » Mon Mar 23, 2015 7:02 pm

Ludo wrote:More interestingly for me, I'd like to see more photos from the ISS looking at Earth during the eclipse..
Astro Samantha posted quite a few of them, including one of the umbra.

Image
I think this is it: the umbra. by AstroSamantha, on Flickr

Image
20 March solar eclipse at sunrise by AstroSamantha, on Flickr

Image
20 March solar eclipse by AstroSamantha, on Flickr
Just call me "geck" because "zilla" is like a last name.

Ludo

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Ludo » Mon Mar 23, 2015 11:20 pm

Thanks Geck for the swift reply. I've seen those but I sort of expected more from different angles given their large field of view. That one penumbra shot also intrigues me since the skies were clear over Norway where the eclipse was total. Although.. thinking a bit more about it I guess the umbra's "trail" could've passed through the arctic where the shot would've been more plausible.

Any clues on where that umbra was exactly?

User avatar
Chris Peterson
Abominable Snowman
Posts: 15248
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Chris Peterson » Mon Mar 23, 2015 11:45 pm

Ludo wrote:Thanks Geck for the swift reply. I've seen those but I sort of expected more from different angles given their large field of view.
Their field isn't as large as you might think. The horizon is only a couple thousand kilometers away, and you can only see reasonable detail for probably six or seven hundred kilometers. They could easily have missed the eclipse completely.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
alter-ego
Serendipitous Sleuthhound
Posts: 877
Joined: Mon Apr 21, 2008 4:51 am
Location: Redmond, WA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by alter-ego » Mon Mar 30, 2015 4:45 am

Chris Peterson wrote:
Ludo wrote:Thanks Geck for the swift reply. I've seen those but I sort of expected more from different angles given their large field of view.
Their field isn't as large as you might think. The horizon is only a couple thousand kilometers away, and you can only see reasonable detail for probably six or seven hundred kilometers. They could easily have missed the eclipse completely.
Yes, throughout the entire 4-picture sequence (From ISS and the transit), the umbra was not yet visible. However, if the ISS ran 15 minutes later, it would crossed the terminator right on the edge of the emerging umbra. I made a composite in Google Earth showing the ISS orbital positions for each of the four pictures. Even on the 2nd pass, ISS totally missed the penumbra. Commenting on the Earth picture taken at 9:01, the umbra would not have been visible for about another 10 minutes. The visible shadow must be some shadow gradient nearing inner penumbral edge.
Google Earth, ISS Orbit and Solar Eclipse.JPG
Nitpicker wrote:
Guest wrote:I'm having a difficult time proving this alignment happened. Where was ISS Mar 20 2015 9:20 UT?
The ISS is directly above the Earth (and the Sun and the Moon) at all times. :wink:

According to Mr Legault's page (available from the APOD caption) -- http://www.astrophoto.fr/eclipse-iss-20150320.html -- the transit happened at 09:05:04 UT. The timing can be quite sensitive to observation location on Earth (and also the ISS boost schedule, see: https://www.heavens-above.com/IssHeight.aspx).
I found the timing of 9:05:04 is indeed duplicated by Stellarium when the correct TLE set (and maybe Stellarium version?) is used.
You do not have the required permissions to view the files attached to this post.
Last edited by alter-ego on Tue Mar 31, 2015 3:30 am, edited 1 time in total.
A pessimist is nothing more than an experienced optimist

User avatar
geckzilla
Ocular Digitator
Posts: 9101
Joined: Wed Sep 12, 2007 12:42 pm
Location: Modesto, CA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by geckzilla » Mon Mar 30, 2015 6:08 am

Cool graphic, alter-ego. I've tried doing something similar with Google Earth before and found it is not as easy as it looks. It's fun to try to place the camera at ISS altitude and see how close it is to Earth. People imagine that you can see the whole planet from up there but the orbit is actually close enough that is impossible.
Just call me "geck" because "zilla" is like a last name.

User avatar
alter-ego
Serendipitous Sleuthhound
Posts: 877
Joined: Mon Apr 21, 2008 4:51 am
Location: Redmond, WA

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by alter-ego » Mon Mar 30, 2015 6:22 am

geckzilla wrote:Cool graphic, alter-ego. I've tried doing something similar with Google Earth before and found it is not as easy as it looks. It's fun to try to place the camera at ISS altitude and see how close it is to Earth. People imagine that you can see the whole planet from up there but the orbit is actually close enough that is impossible.
Thank you, geck.
You're absolutely right. As has been pointed out before, ISS horizon is around 1400 miles (radius). The CalSky picture shows the ISS position when the penumbral picture was taken (9:01UT). The deformed egg-shape (cyan) surrounding the ISS is the nominal visible horizon.
ISS Horizon Relative to Earth.JPG
You do not have the required permissions to view the files attached to this post.
A pessimist is nothing more than an experienced optimist

Roberto Capacci
Ensign
Posts: 14
Joined: Fri Apr 10, 2015 7:09 am
Location: Arezzo (Italy)

Re: APOD: A Double Eclipse of the Sun (2015 Mar 22)

Post by Roberto Capacci » Fri Apr 10, 2015 7:49 am

Amazing! :)