At What Altitude Can Stars Be Seen In Daylight?

[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.com/watch?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.com/watch?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.nationalgeographic.com/news/2012/10/121008-joseph-kittinger-felix-baumgartner-skydive-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.com/2014/10/25/science/alan-eustace-jumps-from-stratosphere-breaking-felix-baumgartners-world-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://ascentmagazine.com/articles.aspx%3FarticleID=195&page=read&subpage=past&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.osapublishing.org/josa/abstract.cfm?uri=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?

 

[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.com/watch?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.osapublishing.org/josa/abstract.cfm?uri=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 December 2, 2018 by hazelm

[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.timeanddate.com/astronomy/night/usa/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/tim-peake/2016/03/27/frequently-asked-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.timeanddate.com/astronomy/night/usa/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/tim-peake/2016/03/27/frequently-asked-questions/

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

[spartan45]

The existence of the Hubble Space Telescope is used as proof that stars can be seen in daylight above the atmosphere. The Hubble ST uses 3 spectral ranges, the near-UV (pivoted at 300nm), Visual light (380nm-740nm) and a limited infra-red (800nm-2500nm) capability.   Here’s the thing; can the Hubble ST see stars in daylight using the normal human visual light spectral range (380nm-740nm), or does it have to resort to using the near-ultra violet spectral range ( pivoted at 300nm) to see stars in daylight?

The only other optical space telescope I’m aware of is the Chang’e 3 Lunar-based ultraviolet telescope (LUT). The lander is equipped with a 50 mm (2.0 in) Ritchey–Chrétien telescope that is being used to observe galaxies, active galactic nuclei, variable stars, binaries, novae, quasars and blazars in the near-UV band (245–340 nm), and is capable of detecting objects at a brightness as low as magnitude 13. The thin exosphere and slow rotation of the Moon allow extremely long, uninterrupted observations of a target. The LUT is the first long term lunar-based astronomical observatory, making continuous observations of important celestial bodies to study their light variation and better improve current models.

Ref:  https://en.wikipedia.org/wiki/Chang%27e_3

The  Chang’e 3 Lander, Lunar based telescope, only observes during the 2 week day-light period because the moon rover and lander of China's Chang'e-3 lunar probe mission "sleep" during the 2 week lunar night, enduring extreme low temperatures on the lunar surface.

Ref:  https://earth.esa.int/web/eoportal/satellite-missions/c-missions/chang-e-3#:~:text=26%2C%202013%3A%20The%20moon%20rover,temperatures%20on%20the%20lunar%20surface.

Is it is not only astronauts and visual spectrum cameras that cannot see stars in daylight but space telescopes using the visual spectral range (380nm-740nm) as well, causing them to have to use the near-UV spectral range (245nm-340nm) to observe the stars when not in the shade of a heavenly body.

 

Could this all be linked somehow to the Lunokhod 2’s (16/1/1973 Moon touchdown Soviet ‘Moonwalker’) most interesting discovery using an astrophotometer (an electron telescope without lens) which registered a glow in the lunar sky during the day suggesting that the Lunar sky is surrounded with a swarm of dust particles, with the effect of scattering solar light?

Ref: ‘The Observer’s Book of Unmanned Spaceflight‘ by Reginald Turnill printed 1974, ISBN 0 7232 1522 7. Page 150-151.

[OceanBreeze]

Is this a trick question?

 

Isn't the sun a star?

[spartan45]

Is this a trick question?

 

Isn't the sun a star?

I appreciate the Sun is a star. I must admit the question and wording ‘at what altitude can stars been seen in daylight?’ does seem a bit weird, but then so does the seemingly black void witnessed by astronauts and visual spectrum cameras above the Earth’s atmosphere from spacecraft and the International Space Station when the Sun is not blocked by the Earth. I am now curious how the Hubble Space Telescope overcomes the problem of seeing stars (other than the Sun which it must not look at because it is so bright it would destroy its sensitive instrumentation) in daylight, all I can think of is perhaps Hubble uses its near-UV spectral range capability and/or the tube design shades the lens sufficiently from the Sun’s glare.  Does anyone know?

[spartan45]

Apollo 14 (1971) Astronaut Alan Shepard describes what he sees after disembarking from the ‘Antares’ lunar module “-Look up in the black sky, there’s no reflection no diffusion and seeing another planet; planet Earth.” “It certainly is a stark place here; I think it’s made all the more stark by the sky being completely black.”

REF: The TV documentary ‘Moon Shot’ from the Smithsonian Channel (2020).

Apollo 16 (1972) Mission science experiments included The Far Ultraviolet Camera/Spectrograph which took pictures and spectra of astronomical objects in ultraviolet light. The Far Ultraviolet Camera was deployed in the lunar module's shadow and used a 3-inch telescope to obtain images and spectra at wavelengths between 500 and 1600 Angstroms; (visible light corresponds to wavelengths of 4000-7000 Angstroms).  Stars as faint as magnitude 11, or 100 times fainter than can be seen with the human eye, were recorded. Results were recorded on a film cartridge and returned to Earth for analysis. A total of 178 frames of film were obtained. The telescope was periodically reoriented by the astronauts in order to study various parts of the sky.

This Far Ultraviolet Camera science mission I’d overlooked is interesting, as it shows very faint stars could be seen and captured on film from the Moon in daylight, albeit using far ultraviolet light. It raises the question: why does it seem so difficult to do the same using the visual spectrum? I have never heard of any stars being seen or captured on film even in the shade of a lunar module. I’m still curious if using light beyond the visual spectrum is how the Hubble Space Telescope overcomes the problem of seeing stars in space - when the Sun is not shaded by the Earth - in daylight.

REF https://www.lpi.usra.edu/lunar/missions/apollo/apollo_16/experiments/f_ultra/

Here is another account of the Apollo 16 science experiment:

Astronauts Charles M. Duke Jr., the lunar module pilot, and John W. Young, the commander, spent a little under three days on the Moon in April 1972. Thanks to them, for the very first time, a telescope explored the vastness of space from the surface of another planetary body. Young took the telescope out of its plastic bag and planted it on a tripod in the shadow of the lunar module, so that the instrument would get no direct sunlight. The astronauts re-oriented the telescope several times during their stay so that they could see different parts of the sky. 

REF https://www.nasa.gov/feature/remembering-the-first-moon-based-telescope

The reference below shows pictures taken by the Apollo 16 Moon Telescope

REF https://forum.nasaspaceflight.com/index.php?topic=43699.0

 

[spartan45]

I found a video clip recently posted on Utube interesting as it highlights the subject of the blackness of daytime space:- Astronaut Tim Peake’s ‘UFO Sighting’ in Space   The Graham Norton Show :

Astronaut Tim Peake “In the daytime in space, the space is black, the blackest black you could ever imagine and if see a light it’s another spacecraft coming towards you and we do when cargo vehicles arrive or crew hand-over to come over, you see these lights. On this one day I was looking out and I saw these 3 lights coming over flying in formation and I thought we’re not due a visiting spacecraft today. I called over Jeff Williams my NASA crew mate and hey what do you make of that and he was equally perplexed and then a fourth light joined them in formation and then suddenly we realised that we thought it was lights that were far away, it was actually small droplets of light that were very close and what was happening a liquid was leaking out of the Russian Progress vehicle and it was crystallising instantly and then reflecting in the light. It turned out to be Russian urine that was leaking out”.

Ref: https://www.youtube.com/watch?v=47ahpZWKHF0

The blackness of daytime space is strange. I have no answer as to how the Hubble Space Telescope overcomes the problem of seeing stars using the visual spectrum in the daytime. If you look back to my post showing how a hand-held video camera captured a bright ½ Moon with the star Aldebaran, (brightest star in Taurus (14th brightest of all stars at Mag 1.1)), just below and to the right, here on Earth during night time then you could imagine it must be even easier to do the same at night time in space. Now let’s consider the same circumstances, but during the daytime. On Earth you can still see and video capture the ½ moon because it is so big and bright, but Aldebaran is now blotted out by the light-scattering properties of Earth’s atmosphere. In Space, nothing should have changed, we still can see and video capture the bright ½ Moon - But wait – where did Aldebaran go? there is no light-scattering atmosphere to blot it out in Space, yet all we see is the black of daytime space surrounding the Moon. Just like the scientists of the 1960’s, I’m baffled.

[spartan45]

The reference below seems to promote the idea that stars can be seen while in space during daylight. This is an interesting contradiction, as most evidence seems to point to the day-time view while in space looking away from Earth simply black with no stars (except the Sun) being visible.

#StarTalk #NeildeGrasseTyson Neil deGrasse Tyson Explains The Billionaire Space Race (20 Jul 2021)

https://www.youtube.com/watch?v=ulTQcLFNiTs

 

At 4m42s-5m15s ‘What happens at 100km; you ascend high enough so that there are so few air molecules that there is nothing there to scatter sunlight – and the blue sky – sky blue is scattered sunlight – if you remove the atmosphere cause you’re so high up then there is no blue sky because there is no sky and then the night-time universe reveals itself while the Sun is also in the sky at the same time, so they classify that as space’.

At 7m36s-8m16s ‘Do you need to go up to 62miles, 100km, to see the night sky; no, you can just wait until the Sun sets’. ‘So to say I can now see the night sky I’m in space - after sunset you’re seeing exactly the same night sky’.

A baffling contradiction.

[SylviaSwanson]

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 if the observer knows where to look for them in the sky.

[spartan45]

5 hours ago, SashaM said:

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 if the observer knows where to look for them in the sky.

Why bother going to an altitude of 100,000 ft to see Venus (apparent magnitude of - 4.5), Jupiter (apparent magnitude - 2.94), Mars (maximum apparent magnitude - 2.94), and exceptionally, (see reference), Sirius (apparent magnitude - 1.45) when it is just possible under ideal circumstances to see them from the ground in daylight.  https://skyandtelescope.org/observing/how-to-see-sirius-in-the-daytime/

Of the four above I’ve only ever seen Venus from the ground during daylight, but it seems others have found it possible to see them. That said the evidence remains that with very few exceptions, the black void of daytime space mysteriously hides the heavens from astronauts and their visual spectrum cameras.

[bangstrom]

Arthur Eddington famously photographed stars appearing near the sun from the surface of the Earth during a total solar eclipse in 1919.