STEREO [Solar Terrestrial Relations Observatory] is a pair of telescopes parked in the L4 and L5 solar Lagrange points. These are along Earth orbit about 93 million miles ahead and behind us.
STEREO-A's Heliospheric Imager captured Comet ISON tracking left to right as it heads toward its close encounter of the hot kind: it will graze the sun on Thursday.
The video covers
Nov. 20 to Nov. 22, 2013.
The smaller moving body seen in the middle ground is Comet Encke. The sun is off-stage right. The instrument visualizes the solar wind, which is also kool.
BTW, Mercury is not farther from the Sun than Earth. It's the perspective. Here is the position of the two STEREO satelites as of 27 Nov 2013. Put yourself at A (the one Ahead of the Earth and look back toward the Earth and you will see why Mercury looks farther from the Sun.
The OFloinn's random thoughts on science fiction, philosophy, statistical analysis, sundry miscellany, and the Untergang des Abendlandes
Reviews
A beautifully told story with colorful characters out of epic tradition, a tight and complex plot, and solid pacing. -- Booklist, starred review of On the Razor's Edge
Great writing, vivid scenarios, and thoughtful commentary ... the stories will linger after the last page is turned. -- Publisher's Weekly, on Captive Dreams
Great writing, vivid scenarios, and thoughtful commentary ... the stories will linger after the last page is turned. -- Publisher's Weekly, on Captive Dreams
Tuesday, November 26, 2013
Subscribe to:
Post Comments (Atom)
Whoa, What's This?
adam
amateur theology
anthropology
aphorisms
Aquinas
argument from motion
Aristotelianism
art
atheism
autumn of the modern ages
books
brains
breaking news
captive dreams
cartoon
charts
chieftain
clannafhloinn
comix
commentary
counterattack
crusades
culcha
dogheads
easton stuff
economics
eifelheim
evolution
factoids on parade
fake news
fallen angels
Feeders
fir trees in lungs
firestar
flicks
floods
flynncestry
flynnstuff
forecasts
forest of time
fun facts
gandersauce
gimlet eye
global warming
glvwg
headlines
henchmen
high frontier
history
home front
how to lie with statistics
humor
Hunters Moon
hush-hush
hypatia
in the house of submission
irish
Iron Shirts
irrationalism
january dancer
jihad
journeyman
kabuki
kool
letter
lion's mouth
lunacon
maps
mayerling
medieval
metrology
miscellany
modern mythology
moose zombies
music
new years
nexus
odds
odds and ends
paleofuture
passing of the modern age
philosophy
philosophy math
poetry
politics
potpourri
psyched out!
public service
quality
quiet sun
quote of the day
razor's edge
redefinition of marriage
religio
reviews
river of stars
scandal
science
science marches on
scientism
scrivening
shipwrecks of time
shroud
skiffy
skiffy in the news
skools
slipping masks
some people will believe anything
stats
stories
stranger things
the auld curmudgeon
the madness continues
the new fascism
the russians are coming
the spiral arm
the writing life
thomism
thought for the day
thread o' years
tofspot
topology
untergang des abendlandes
untergang des morgenlandes
up jim river
video clips
vignettes
war on science
we get letters
we're all gonna die
whimsy
words at play
wuv
xmas
you can't make this stuff up
Thanks for this TOF. I was unaware that we had placed sattelites of any kind along our orbit, so far from Earth itself.
ReplyDeleteIf the Earth is 93 million miles from the Sun, then from the image STEREO would have to be much further from Earth than that.
This comment has been removed by the author.
DeleteThis comment has been removed by the author.
DeleteTOF, these satellites are not parked in L4 and L5 Lagrange points. They are actually orbiting the Sun roughly along Earth's orbit. You can see this by changing the dates on the "STEREO Orbit Tool" page at http://stereo-ssc.nascom.nasa.gov/cgi-bin/make_where_gif
DeleteYou can see, for example, that the two objects will pass each other around 20 March 2015.
There are Lagrange points in gravitational system: the original ones are the leading and trailing Trojans in Jupiter orbit, as a result of the Sun-Jupiter balancing points. The one's you are thinking of are the Earth-Moon Lagrangian points. But there are also the Sun-Earth Lagrangians.
DeleteThe STEREO satellites are not on anything's Lagrange points.
DeleteThe Sun-Earth Lagrange points are "fixed" relative to the Earth; the L4 and L5 Lagrange points stay roughly 93 million miles ahead of and behind the Earth.
The STEREO satellites, however, are moving relative to each other and to the Earth. They will pass each other 20 March 2015 (something Lagrange points cannot do), and they will eventually pass close to the Earth as well.
I looked into this further, and found an early planning document for the STEREO effort dated Dec 1 1997. It is a PDF of a photocopy, so you cannot search the text in it. But it is a worthy read. (I saved a copy to disc, because this kind of stuff can disappear into the digital dark age abyss, like comments have done at First Things!)
ReplyDeletehttp://stereo-ssc.nascom.nasa.gov/publications/stdt.pdf
Page 36 of the PDF (p. 28 of the report) has this:
"We recommend that the STEREO mission consist of two identically instrumented Sun-pointed spacecraft at 1 AU. The spacecraft should slowly drift away from Earth, so that after 2 years, STEREO #1 will lead Earth by 45° and STEREO #2 will lag by 60°."
Page 39 of the PDF (31) has this:
"Phase4: Global Solar Evolution and Space Weather (after day 1100, α > 180°) When the separation of each STEREO spacecraft from the Sun-Earth line becomes greater than 90°, events on the far side of the sun that launch particles toward Earth will be visible for the first time."
I also read something in there about "adopting a heliocentric orbit", but I cannot find that now.
So it seems from this that the plan was not to use Lagrange points originally. This doesn't of course mean that they didn't decide to adopt Lagrange points. It does look from the orbit movies that they started them out close to L4 and L5. But from the position calculator at the NASA site, they have long since moved away from them, which was the plan according to the doc. I cant help wondering now whether L4 and L5 are "reserved regions"... a big spherical barb wire fence with laser guns LOL... a stable bit of real estate (unreal estate?) like that could be very valuable. Maybe they were told "um no, you WONT be setting up residence in Lagrange 4 or 5".
It is great finally to find where YOS writes. It is a surprise to me to find that you write SF, but I am going to have to check it out now (I think it has been 35 years since I read anything SF).