# Debunked: Earth is moving too slowly as seen from STEREO Ahead

#### Astro

##### Senior Member
STEREO is a NASA mission consisting of two satellites, one ahead of the Earth's orbit, and one behind. They both have a variety of instruments, including five cameras, two of which are specifically for photographing the Sun's corona, COR1 and COR2

Earth has been visible on STEREO Ahead in the COR2 imager since December 18th. Since that time it has moved very slowly across the image, moving only about half a degree in the course of a month. This caused ThorNews on YouTube to claim that Earth "stood still" for a month and that this was highly unusual.

In fact it's perfectly normal. I created a spreadsheet to calculate where Earth should be in the COR2 images relative to the sun. The images from STEREO Ahead are currently all beacon quality (256x256 native resolution) due to bandwidth limitations imposed by the side-lobe operations of its antenna as it orbits to the opposite side of the sun (heating of the feed horn required off-pointing the antenna to lower the temperature since it has to increasingly point towards the sun to also point towards the earth). I calculated the sun-earth separation as seen by STEREO Ahead's position in orbit around the sun and then converted this to a pixel value based on astrometry of an old COR2 image ( http://nova.astrometry.net/user_images/566023#annotated ) accounting for the 8 fold decrease in current resolution.
http://dropcanvas.com/nhcs7
The spreadsheet correctly predicts the location of Earth relative to the sun in the COR2 images and proves that the motion is normal and expected given the orbits of earth and STEREO:

This makes intuitive sense when you realize that STEREO Ahead is in a very earth-like orbit. It originated from earth and it only has a slightly smaller semi-major axis than earth. It therefore orbits the sun nearly at the same speed as earth, only slightly faster. Earth will therefore exhibit a very slow motion relative to the sun as seen from STEREO Ahead. You can double check the functionality of the spreadsheet by substituting the orbital elements of other planets farther from the sun than STEREO Ahead (earth falls into the category of an "outer planet" to STEREO Ahead ever so slightly) into the place of earth's orbital elements in the spreadsheet. I was able to correct predict the entry of Jupiter into the COR2 field of view using the spreadsheet. Jupiter will proceed quickly across COR2's field of view, passing the earth, because it is in a vastly different orbit with a much larger semi-major axis, therefore STEREO orbits the sun much faster than Jupiter.

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I liked this post because....well....I have this 'opinion' that often....TOO often....some peoples' perceptions of how space actually is can be unfairly influenced by certain 'Science-Fiction' depictions, over the years (not 'calling out' any particular media source....YOU "know" who you are!! And, I kid of course....not about my content, but about the 'calling out' bit. THAT was a joke, aimed solely at those who WRITE bad Science Fiction, for the mass-media consumption audience).

Trying to peel myself out of the pit I just dug ... yes, it is important to understand how orbits actually work.

'IF' anyone is interested in further "research"? Might I suggest a down-load (It's FREE!!) of stellarium?

EDIT again.....I just checked...."Stellarium" (already ON my hard-drive, and safe as can be) seems to not be accessible on-line, any more.....I am so sad...

Follow-on....looked up on Wiki:

http://en.wikipedia.org/wiki/Stellarium_(computer_program)

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I've added an explanatory opening paragraph to that, as not everyone is familiar with the STEREO mission

EDIT again.....I just checked...."Stellarium" (already ON my hard-drive, and safe as can be) seems to not be accessible on-line, any more.....I am so sad...

Stellarium is still downloadable in a variety of flavors: http://www.stellarium.org/

OK!! GOOD NEWS, EVERYONE!! (Sorry, had to "quote" the "professor" from the fictional cartoon show "Futurama".)

Adding? A chagrined emotie...hmmm....which one to choose?...

I think pretty much ALL Science fiction depictions with the possible exception of Arthur c Clarke give people a skewed idea of what space is like.
What's worse is that because we are so used to these tropes now we will get confused if we see something a more realistic approach.
these tropes include space being like an Ocean where (Star Trek TOS is a good example here) spacecraft always approach each other in the same orientation so a derelict ship can be shown "listing" by just showing it at a different angle to anyone else.
People just jump into a ship like it's a car and off they go.
space Dogfights happen like atmospheric dogfights. lopping and rolling round each other etc, cos it looks cool. In Real life, if we had 2 armed shuttles and you were coming behind shooting me (we aren't going to ask what with at this point) I could simply do a couple of retro rocket burns and spin my craft round to face you without changing its direction of travel to shoot back. I would like to see that in a film, even speeded up to normal action film speeds.

I think the Space Odyssey ones are better where they do have to loop round a planet to slow down or speed up significantly and if they cock it up even slightly they are dead.

And then there;s the stars going past the spaceship to give an impression of movement etc.

Actually grasping the 3 dimensional movement of objects relative to each other is pretty hard, but some people really are looking far too hard for "anomalies" without learning what they SHOULD see first.

And then there;s the stars going past the spaceship to give an impression of movement etc.

Yeah.....as a self-proclaimed "Star Trek apologist"? I chalk that up to 'Hollywood-ism' (another term that I just made up).

I've always maintained that the "stars going past" out the portholes, or "windows" of a "Star Trek" era starship were "representations" that were displayed IN those windows (or portholes) so that the crew had a sense of what the ship was doing....in other words, if a crewmember woke up and was to begin his/her/its duty roster? He/She/It could immediately look at the porthole and know if the ship was at Warp....or sub-light.

BUT? To get back to topic....the claims that the Stereo-Ahead satellites show that Earth is moving too slowly are inaccurate because? THOSE satellites are orbiting in their own manner....IT is ALL about perspective.

(This is a difficult concept to convey to people, sometimes....it is about "orbital mechanics" --- a term I highly recommend people should "Google" --- it is extremely complex).

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I've always maintained that the "stars going past" out the portholes, or "windows" of a "Star Trek" era starship were "representations" that were displayed IN those windows (or portholes) so that the crew had a sense of what the ship was doing....in other words, if a crewmember woke up and was to begin his/her/its duty roster? He/She/It could immediately look at the porthole and know if the ship was at Warp....or sub-light.
In Star Trek, those aren't stars, they're particles caught in the navigational deflector field. Which is why they regularly pass between the ship and camera in close up shots.

This animation illustrates it perfectly. Like midnight on a carousel ride...

In Star Trek, those aren't stars, they're particles caught in the navigational deflector field. Which is why they regularly pass between the ship and camera in close up shots.
I don;t think they made up that explanation until after everyone complained.
They could have just said "look, we need to show movement somehow, just grow up and stop being so petty" but they didn't.

This is why people shouldn't take as gospel the supposedly scientific things that are talked about or shown in science fiction. Even great science fiction is prone to be inaccurate in some way, shape, or form, in order to serve the purposes of the story or the expectations of the majority of consumers (who are not scientists).

To me, its not so much the stories' collective fault, as it is people sometimes not understanding the line between fiction and reality. Of course it can have the adverse effect of convincing people that things like this satellite's images are somehow unusual because of what they have supposedly "learned" whilst watching or reading these works of fiction. But I have yet to see a good science fiction story that claims itself to be 100% accurate to the realities of the universe without taking any liberties, and I'm more prone to fault the people for taking too seriously what a fictional story is showing or telling them.

This is why people shouldn't take as gospel the supposedly scientific things that are talked about or shown in science fiction. Even great science fiction is prone to be inaccurate in some way, shape, or form, in order to serve the purposes of the story or the expectations of the majority of consumers (who are not scientists).

To me, its not so much the stories' collective fault, as it is people sometimes not understanding the line between fiction and reality. Of course it can have the adverse effect of convincing people that things like this satellite's images are somehow unusual because of what they have supposedly "learned" whilst watching or reading these works of fiction. But I have yet to see a good science fiction story that claims itself to be 100% accurate to the realities of the universe without taking any liberties, and I'm more prone to fault the people for taking too seriously what a fictional story is showing or telling them.

Part of the issue is so much of science fiction has become science fact in one way or another.. Nuclear powered subs via 20k Leagues, PADDs from TNG becoming iPads and tablets, TOS communicators becoming cell phones, view screens becoming video chat via Skype and laptops (TNG.. look on the desks). Like weed said.. it all muddles together after a while.

Yeah, it can muddle together because of sci-fi's penchant for accurate predictions of the future. Star Trek is a great example of that. But there's several major things in Star Trek you can call out for containing a bit of the fantastical in their portrayals too, e.g. the Holodeck and the warp core.

I think it comes down to understanding how predictive science fiction can be, without losing sight of those fictional story elements. Can be difficult to do when it muddles together through some basis in real tech or an accurate prediction of future tech, but still.

This animation illustrates it perfectly.

Yes. Yes, indeed. Related possibly to the thread topic is the refutation of "geo-centrism"....in a series of brilliantly produced YouTube videos. I will link only the first (the ones that follow this are easily found): Testing Geocentrism - Part 1.

They are quite an enjoyable and entertaining watch....

(NOTE please, that the author and producer of the videos can be "impolite" at times, in his narration and references...which I think is understandable, given the topic).......

Correct me if I'm wrong, but an easy way of debunking this is by saying that if we were moving too slow, we would currently be falling into the sun, which we obviously aren't.

As much as I love Star Trek, it's important to remember the writers aren't/weren't astrophysicists and while there certainly are some sciencey things about it, the show is simply for entertainment.

if we were moving too slow, we would currently be falling into the sun

Yes! THAT is the correct answer.

"IF" (by some 'magical' means) the velocity OF Earth in its orbit were slowed....then the orbital trajectory would change...."slower" means usually...closer to the main governing gravitational mass....(which would be our Sun).

I will ADD another educational video to describe orbital mechanics...(I hope it's relevant?) Optional to view, IT is VERY deep....takes many viewings to absorb.....but one that I tend to use for myself, in order to learn:
Space Flight: The Application of Orbital Mechanics

I think this NASA video was used to help orient non-pilots who were assigned to Space Shuttle missions. (This is "my" take on the video....I have nothing to back up that belief).

STILL?? The video is excellent in explaining the physics of orbits.

ALSO to add? In space....things might be inclined to "orbit" one another...BUT ONLY if there was some initial force to instigate the motion....The commonly used "forces" involve factors that FAR exceed Human lifetimes....so, must be 'intuited'...THESE types of forces and reactions take millions....or even BILLIONS of what "we" (here on THIS planet) define as a "YEAR".

OTHER planets that orbit OTHER stars?

"THEY" will (obviously) have a different sort of "Time Reference".....it's so obvious ("Star Trek" and other "TV" Science Fiction aside!!...)

"WHEN" (or "if") we ever encounter non-Earth species?? WHO happen to travel FROM their planet, to HERE??

I think the first and foremost issue will be...."communication".....

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