7 replies to this topic

[spartan45]

What is the lowest altitude you can see stars in daylight is a question I have wondered about because of the well documented black starless daytime sky seen at high altitude. I can’t find any written reference to seeing stars in daylight from high altitude aircraft, balloons or near Earth orbiting craft such as the International Space Station (ISS). One reason I have seen put forward as to why it is difficult to see stars from the ISS in daylight is the glare of the Sun  blots out the stars just like a full moon does when viewing the sky from the Earth at night. It seems a waste that adjustable shades couldn’t be fitted to the upper window(s) of the ISS to deal with this glare. Another reason is the bright lighting inside the ISS, but could I suggest a blackout curtain around the window or local light switch? The only written example of seeing stars in daylight I found is from cislunar space (the space between Earth and Moon). I would like to know if anyone has found an example of seeing stars in daylight at an altitude below this. My findings are below.

Google: Professor Brian Cox English Electric Lightning flight

Professor Brian Cox reaches 60,000ft (18km) demonstrating the deep dark blue sky at this altitude. This was filmed in 2009.

https://www.youtube....h?v=qwgfU228clE

Google: James May on the edge of space

James May finally reaches 70,000ft, where he looks down at the curvature of the earth, and upwards into the black infinity of space. This was filmed in 2009.

https://www.youtube....h?v=jIJRoj2qwsc

Google: Kittinger for National Geographic magazine

Extract: By Capt. Joseph W. Kittinger, Jr., USAF, for National Geographic magazine:

Overhead my onion-shaped balloon spread its 200-foot [61-meter] diameter against a black daytime sky. More than 18 1/2 miles [30 km] below lay the cloud-hidden New Mexico desert to which I shortly would parachute.

 It was about 0700 local the Excelsior 3 was launched with Capt. Joeseph W. kittinger, Jr. USAF on board , lifted by a helium balloon to 102,800ft, (31.3km), (19.45 statute miles), on 16 Aug 1960, above New Mexico.

https://news.nationa...kydive-science/

Google: alan eustace ny times

Extract of NY Times article:

By Alan Eustace, 57, a senior vice president of Google:

“It was beautiful. You could see the darkness of space and you could see the layers of atmosphere, which I had never seen before.”

 It was dawn Oct. 24, 2014 when Alan Eustace was lifted from an abandoned runway at Roswell airport, New Mexico by a balloon filled with 35,000 cubic feet of helium.

Mr Eustace’s maximum altitude was initially reported as 135,908 feet but based on information from two data loggers, the final number submitted to the World Air Sports Federation was 135,890 feet, (41.42km), (25.74 statute miles).

The previous altitude record was set by the Austrian daredevil Felix Baumgartner, who jumped from 128,100 feet (39.05km), (24.26 statute miles), on Oct. 14, 2012, New Mexico.

https://www.nytimes....rld-record.html

Google: An interview with Apollo 14 astronaut

Extract from: an interview with Apollo 14 astronaut Dr. Edgar Mitchell
by Sarah E. Truman (Editor of Ascent magazine)

Sarah E. Truman (editor of ascent magazine):  In 1971, as you pulled away from the Moon and made your way back to Earth, what did it feel like to be in the space between worlds?
Dr. Edgar Mitchell :  I’ll have to set up the story for you just a little bit. The spacecraft was oriented perpendicular to the plane that contains the Earth, the Moon and the Sun. Not flying perpendicular to that plane – but moving through it back to Earth. The spacecraft was rotating to maintain the thermal balance of the Sun. What that caused to happen was that every two minutes, with every rotation, we saw the Earth, the Moon and the Sun as they passed by the window. The 360-degree panorama of the heavens was awesome and the stars are ten times as bright and, therefore, ten times as numerous than you could ever see on a high mountaintop on a clear night. It was overwhelmingly magnificent.

http://ascentmagazin...issueID=30.html
 

[spartan45]

A mystery for me about seeing stars at altitude in daylight is the lack of data on the subject. 

If you Google: At what altitude can you see stars in daylight? The top result is an abstract of an article titled ‘The Visibility of Stars at High Altitude in Daylight’ by Koomen, M. J. printed in the Journal of The Optical Society of America 49(6) pages 626-629 published in 1959. https://www.osapubli...i=josa-49-6-626

Here is an extract of the abstract:

The daylight visibility of stars has been investigated for an observer altitude of 100 000 ft., using published visual threshold data and calculated sky luminance. Venus, Jupiter, and Sirius, plus Mars at its brighter phases, can be detected with the naked eye. The daytime sky will not exhibit nighttime luminance until an altitude of roughly 100 km has been reached, assuming no contribution from airglow.

Now, no disrespect to this interesting article, but here we are in 2018 and apparently no further forward on the subject. Also, although many people find the high altitude black starless daylight sky difficult to accept, other than the 1959 article, very little information on this subject seems available to explain it, no wonder this topic is poorly understood. Would anyone else agree?

[spartan45]

To anyone interested in true story space adventure, I recommend ‘Secret space escapes’ (2015).The part of this series relevant to this post is ‘shipwrecked P2’at 12m26s through to 13m where astronaut Mike Foale mentions ‘you can’t see the stars during the day’ when describing how the stars were used as reference points for stabilizing the Mir space station’s tumbling spin. Not really surprising because of the Sun’s glare, but reinforces that even at an altitude of about 270 miles, stars cannot be seen in daylight. 

[spartan45]

To capture stars using a still camera it is usual to employ a 15sec exposure but a camcorder records at either 30 (NSTC ) or 25 (PAL) frames per second so a camcorder is better suited than a normal still camera to use from a moving spacecraft. In this post I’ll show that even with a little light pollution, thin low clouds and a high half Moon at night here on Earth, stars that can be seen easily with the naked eye can also be captured using a camcorder like the Sony DCR-DVD handycam. The Sony has ’NightShot’, super ’SteadyShot’, 20x optical zoom (other models have more) and the ability to disable auto for manual infinity focus. I used it (no tripod, simply hand held) on 23/24^th February 2018 to first capture Aldebaran, (brightest star in Taurus (14^th brightest of all stars at Mag 1.1)), just below and to the right of a bright half Moon. Then I selected the Gemini twins, from left to right: Pollux (17^th brightest, Mag 1.2) and Castor (24^th Mag 1.6). Finally, the three stars of Orion’s belt, from left to right: Alnitak (33^rd Mag 2.0), Alnilam (29^th Mag 1.8 Mintaka (67^th? Mag 2.5, the dimmest of all captured). All the above were near and below the bright half Moon. The pictures posted are individual frames at between zero 0x and twenty 20x magnification from the video footage.  Now to ask the question: if shielded from the glare of the Sun by the bulk of the Soyuz/space station etc., could stars be seen by the naked eye or captured by the likes of the Sony handycam camcorder in daylight?

 

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[spartan45]

Here is an interesting 1965 documentary   ‘BBC Horizon, 1965 Man in Space’

The space race was about the halfway point. Interest in space exploration was intense and yet it appears no answer was found to what altitude can stars be seen in daylight because at about two minutes into the ‘BBC Horizon, 1965 Man in Space’ documentary Frank Borman states ‘During the daytime we were unable to see the stars, this confounds the scientist, but perhaps it was due to light scattering on our windows or perhaps it was due to the Earthlight reflection. We were unable to see the stars in the daytime.’  The interviewer states ‘But when you get to the Moon you will be able to see the stars’ Frank Borman replies ‘We hope so. The reason we hope so of course is our navigation depends on seeing the stars.'

Frank Borman was commander, (Jim Lovell co-pilot), on Gemini 7 It was their first space flight. Gemini 7 completed 206 circular orbits at 300km (162nm) altitude. 

Launch date: Dec 4 1965, return date:  Dec 18 1965.

This documentary is evidence that anyone wondering at what altitude stars can be seen in daylight is in good company with the scientists of 1965.

Ref:

https://www.youtube....h?v=YqlrV_l25uw

[hazelm]

A mystery for me about seeing stars at altitude in daylight is the lack of data on the subject. 

If you Google: At what altitude can you see stars in daylight? The top result is an abstract of an article titled ‘The Visibility of Stars at High Altitude in Daylight’ by Koomen, M. J. printed in the Journal of The Optical Society of America 49(6) pages 626-629 published in 1959. https://www.osapubli...i=josa-49-6-626

Here is an extract of the abstract:

The daylight visibility of stars has been investigated for an observer altitude of 100 000 ft., using published visual threshold data and calculated sky luminance. Venus, Jupiter, and Sirius, plus Mars at its brighter phases, can be detected with the naked eye. The daytime sky will not exhibit nighttime luminance until an altitude of roughly 100 km has been reached, assuming no contribution from airglow.

Now, no disrespect to this interesting article, but here we are in 2018 and apparently no further forward on the subject. Also, although many people find the high altitude black starless daylight sky difficult to accept, other than the 1959 article, very little information on this subject seems available to explain it, no wonder this topic is poorly understood. Would anyone else agree?

 

Maybe I am missing something in your post  but two things:  (1)  Venus, Jupiter and Mars are not stars.  Did you mean to limit to stars?  (2)  Venus can be seen in early daylight when it  rises just before sunup and that is at whatever altitude Missouri is at.  You never see Venus at any other time - not even at midnight - but only just before sunrise and just after sundown.  But, as I said, Venus us not a star.  As for Jupiter and Mars - also not stars - I'll leave it to those who have climbed higher. I don't think I have ever seen either in daylight.  Sirius?  Now you are looking for a star in daylight.

 

All that said, your question is interesting.  How high would you have to go before you would see stars in daylight?  I'm not sure you ever would.  And if you use artificial shades, etc., haven't you created darkness?  You would then be talking about time, not light.  12:00 noon - daylight time.  Block out the sun and moon, it's still daylight time but it's not day light.  I think some eclipses can make it that dark. Then you might see stars in day light time.

 

Sorry if I am nitpicking and not making sense.  But your very good question had my brain in turmoil.  Other than Venus or a very dark eclipse?  Start climbing.  Good luck.

Edited by hazelm, 02 December 2018 - 11:28 AM.

[spartan45]

Maybe I am missing something in your post  but two things:  (1)  Venus, Jupiter and Mars are not stars.  Did you mean to limit to stars?  (2)  Venus can be seen in early daylight when it  rises just before sunup and that is at whatever altitude Missouri is at.  You never see Venus at any other time - not even at midnight - but only just before sunrise and just after sundown.  But, as I said, Venus us not a star.  As for Jupiter and Mars - also not stars - I'll leave it to those who have climbed higher. I don't think I have ever seen either in daylight.  Sirius?  Now you are looking for a star in daylight.

 

All that said, your question is interesting.  How high would you have to go before you would see stars in daylight?  I'm not sure you ever would.  And if you use artificial shades, etc., haven't you created darkness?  You would then be talking about time, not light.  12:00 noon - daylight time.  Block out the sun and moon, it's still daylight time but it's not day light.  I think some eclipses can make it that dark. Then you might see stars in day light time.

 

Sorry if I am nitpicking and not making sense.  But your very good question had my brain in turmoil.  Other than Venus or a very dark eclipse?  Start climbing.  Good luck.

(1) No, I simply wanted to keep the question short.

(2) Venus has an apparent magnitude of about -4.8, brighter than the estimated -2.2 of the sky as seen from the ground in daylight, so may be visible then.  Jupiter is too close to the Sun and too dim at -1.74. Sirius -1.47, not present during daylight and too dim anyway, Mars 0.05, too dim. Except for the estimated -2.2 of the sky from ground level, apparent magnitude and relative position of the planets and star listed will vary with time and location so only valid 5^th Dec 2018.

Ref:  https://www.timeandd.../jefferson-city

The shades around the windows to stop glare would only need to be similar to a driver’s pull down sun visor, but on the outside of the window and manipulated from the inside.

 See below how the black space in daylight surprises even a modern day astronaut:

Astronaut Tim Peake, 15 Dec 2015 launched to the International Space Station (ISS), returned 18 Jun 2016. Extract of: New answers 6 Jun 2016, Q24 Tim Peake replied ‘The thing that most surprised me was how black space appears during the day. You know that stars are out there, but because your eyes adjust for brighter objects, space looks so incredibly dark’. For the complete Q&A see Ref below.

Ref: http://blogs.esa.int...sked-questions/

[hazelm]

(1) No, I simply wanted to keep the question short.

(2) Venus has an apparent magnitude of about -4.8, brighter than the estimated -2.2 of the sky as seen from the ground in daylight, so may be visible then.  Jupiter is too close to the Sun and too dim at -1.74. Sirius -1.47, not present during daylight and too dim anyway, Mars 0.05, too dim. Except for the estimated -2.2 of the sky from ground level, apparent magnitude and relative position of the planets and star listed will vary with time and location so only valid 5^th Dec 2018.

Ref:  https://www.timeandd.../jefferson-city

The shades around the windows to stop glare would only need to be similar to a driver’s pull down sun visor, but on the outside of the window and manipulated from the inside.

 See below how the black space in daylight surprises even a modern day astronaut:

Astronaut Tim Peake, 15 Dec 2015 launched to the International Space Station (ISS), returned 18 Jun 2016. Extract of: New answers 6 Jun 2016, Q24 Tim Peake replied ‘The thing that most surprised me was how black space appears during the day. You know that stars are out there, but because your eyes adjust for brighter objects, space looks so incredibly dark’. For the complete Q&A see Ref below.

Ref: http://blogs.esa.int...sked-questions/

Surprises me, also.  You are drawing a picture that I cannot even imagine but  I keep thinking about it.