49 votes

Why does the sky of Mars appear blue in this video of pictures sent back by the Chinese rover?

Despite my comments about the sky not always being red, I think there is a simpler explanation. This video was made by a "content" company on a monetized YouTube channel. The screenshot is ...
uhoh's user avatar
  • 149k
37 votes

Is there any way that real stars would move like they do in the classic Windows 3.x screensaver if traveling through space at extreme speed?

I do disagree with the other answers, not on the result, but on the reason. You don't need to go faster than the speed of light to pass through multiple stars in a few seconds. Putting aside the ...
lvella's user avatar
  • 471
29 votes
Accepted

Is this plot of deep space trajectories correct? Did most launch retrograde from Earth? Why do some change direction between planets?

The diagram you show is the digital version of a drawing by someone with an Etch-a-Sketch: completely inaccurate. The diagram below is accurate, showing Pioneer 10 & 11 and Voyager 1 & 2 ...
Tom Spilker's user avatar
  • 18.3k
22 votes

Why are we not seeing probability curves for space junk collision prediction?

...so couldn't there be a tool? Actually there are such tools. Users just drop in the inputs and a number pops out? It is maybe not such easy but it comes near. relating to [...] position ... ...
CallMeTom's user avatar
  • 3,308
18 votes
Accepted

Which 3D space simulation/visualization software (free or commercial) can I use as a post processor of data calculated with Fortran?

One option is SPICE-Enhanced Cosmographia. You could convert your output text files to SPICE SPK (.bsp extension) kernels or more simply a text file with structured data (see the InterpolatedStates ...
Alfonso Gonzalez's user avatar
9 votes
Accepted

What is the extra moving and disappearing line in the animation in the BulgariaSat-1 webcast?

The blue line represents the part of the satellite's trajectory after it traveled once around the earth, so it's basically the continuation of the 2nd stage track (except that the payload will have ...
Floern's user avatar
  • 1,479
9 votes

Would Jupiter look big?

No, you won't be able to tell immediately, and yes, it will look big. First, I think it's extremely unlikely that a spacecraft could travel to Jupiter without knowing Jupiter's size. However, maybe a ...
Innovine's user avatar
  • 4,605
8 votes

Earth’s Orbit speed and apparent motion question

Firstly, it's going to take a big rocket to do this (larger than any rocket we have built so far btw). We're travelling together with the Earth, so our speed relative to the Earth is 0. Thus, this isn'...
SE - stop firing the good guys's user avatar
8 votes
Accepted

Is GMAT still available? Where? How? (NASA's General Mission Analysis Tool)

If you go beyond the expired certificate, you get a page telling you it is now supported on an off-NASA site:
Brian Tompsett - 汤莱恩's user avatar
8 votes
Accepted

Why does Earth not appear to be at the focus of TESS' elliptical orbit in this video?

I believe it is an effect of the used 3d->2d projection and relative angles of the camera and the shown orbit. I replicated similar Earth center shift using Online Space Orbit Simulator site and ...
jkavalik's user avatar
  • 5,118
7 votes
Accepted

Trying to understand the two "holes" in this alt/az plot of the ISS

Let's try with pictures... First, the frame of reference: Earth. Frame bound to Earth center, spinning with Earth spin. This is the frame of reference which is "immobile" for you and me as we stand ...
SF.'s user avatar
  • 55k
5 votes
Accepted

Why would Mars' sky appear blue at dawn and dusk, but red during the middle of the day (reverse of Earth)?

The picture thumbnailed below from here, originally from NASA, does indeed show a reversed effect from what we see on Earth. Note that the hue of the Sun is not reversed; instead of the orange or red ...
Oscar Lanzi's user avatar
  • 8,495
5 votes
Accepted

Relation between GOCE gravity model and Earth shape

The bumps in a depiction of the geoid aren't just exaggerated. They are vastly exaggerated. The Earth is very close to spherical, with the largest deviation from spherical being the Earth's ...
David Hammen's user avatar
  • 73.8k
4 votes

Why does Earth not appear to be at the focus of TESS' elliptical orbit in this video?

@jkavalik's answer seems to have nailed it, I'll add my own perspective (no pun intended, seriously!) as background. When I looked at the problem I first considered and then rejected distortion due ...
uhoh's user avatar
  • 149k
4 votes

Why does Earth not appear to be at the focus of TESS' elliptical orbit in this video?

3D to 2D is not primary cause. Primary cause is RAAN of two orbits is different. So when you project 3D to 2D, ellipse is slightly rotated. Infact I claim that the angle by which it looks tilted w.r.t ...
zephyr0110's user avatar
  • 2,921
4 votes
Accepted

3D modelling of satellites around the earth

Maybe Systems Tool Kit could be helpful: https://www.agi.com/products/engineering-tools It's a powerful tool, and there is also the possibility to have a free license, although it does not include ...
paolom's user avatar
  • 156
4 votes

Why would Mars' sky appear blue at dawn and dusk, but red during the middle of the day (reverse of Earth)?

I came to this interesting question while discussing a related one: Do the gases in the Earth's atmosphere affect the color of a lunar eclipse?. After thinking on the possible cause for this,"...
Alchimista's user avatar
4 votes

Are there Starlink train-finding websites?

Heavens Above has both "Starlink passes for all objects from a launch" and "Starlink Dynamic 3D Orbit Display" pages that I've used to show Starlink trains to a distant, not-space-...
Erin Anne's user avatar
  • 10.8k
4 votes

Is there any way that real stars would move like they do in the classic Windows 3.x screensaver if traveling through space at extreme speed?

It helps to suppose that you're flying your ship somewhere closer to a galactic nucleus than we are. Sure, the nearest star to us (after the Sun) is several light years away, but if you get within a ...
hobbs's user avatar
  • 927
4 votes
Accepted

Is this JWST Halo orbit plot fouled up somehow?

No, plot is not screwed up. after discussion here and other locations and I now realize that the plots are sound and correct with the only 'problem' being that the +Z label on plot C) is in the wrong ...
BradV's user avatar
  • 3,162
4 votes

Which 3D space simulation/visualization software (free or commercial) can I use as a post processor of data calculated with Fortran?

I would recommend checking out FreeFlyer (although GMAT and STK may be interchangeable in your use case). NASA's Johnson Space Center uses FreeFlyer for space mission design and operations as it ...
Angel Rocha's user avatar
3 votes

Is there a name for views of orbital paths that ignore some motions versus those that don't?

I would like to post a comment, but as I do not have enough "reputation" score to do so, here is my complement to @asdflex's comment. As you probably know, motion is always defined relative ...
Ng Ph's user avatar
  • 2,724
3 votes

What is the extra moving and disappearing line in the animation in the BulgariaSat-1 webcast?

That should be the projected future path on the second orbit. It looks like it is drawn relative to Earth surface (otherwise it would connect directly to current position of the second stage) and that ...
jkavalik's user avatar
  • 5,118
2 votes
Accepted

Why doesn't a full/gibbous moon high in the sky ever seem to look orange? Shouldn't it?

I am surprised this has not already been answered. It makes me feel like I'm missing something, but here goes... But the full or gibbous moon when high in the sky doesn't look orange to me at ...
Aaron's user avatar
  • 256
2 votes

3D modelling of satellites around the earth

SaVi runs under Windows. It can be run under the Windows Linux Subsystem, under Cygwin, or under VirtualBox. And how to get it running is fully documented. See https://savi.sourceforge.io/install/ ...
SaVi's user avatar
  • 21
2 votes

Is the night sky on Earth different from the night sky on the moon or Mars?

According to @RobJeffries' answer: Even in favourable conditions, the optical depth of the Martian atmosphere is usally somewhere between 0.5 and 1 per airmass. (Petrova et al. 2012; Lemmon et al. ...
uhoh's user avatar
  • 149k
2 votes

Is the night sky on Earth different from the night sky on the moon or Mars?

First of all, the distances in the solar system are absolutely tiny compared to the distances between stars. To the casual observer, the celestial sphere (by which I mean everything in the sky except ...
Ingolifs's user avatar
  • 6,428
2 votes

Is there any way that real stars would move like they do in the classic Windows 3.x screensaver if traveling through space at extreme speed?

Yes, via a light-speed U-turn When traveling at speeds close to the speed of light, stars appear to conglomerate into a single blurb in front of a spacecraft (artistic example). When slowing down, ...
Please stop being evil's user avatar
2 votes

Is there a name for views of orbital paths that ignore some motions versus those that don't?

You have to be careful because of the way gravity works. Everything attracts everything, there are no pure Keplerian orbits. But if we ignore that and pretend say that the Sun is fixed, the Earth ...
uhoh's user avatar
  • 149k

Only top scored, non community-wiki answers of a minimum length are eligible