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You are thinking of Vanguard 1 the third satellite ever put into orbit. Its small and its in a 3,840 x 657 km orbit, so its going to be up there for centuries.

Its upper stage booster is still up there too.

https://www.heavens-above.com/...

Someone who doesn't know the difference could certainly mistake the two, but Iridium flares are MUCH slower. They last on the order of (5s-20s), and the brightness profile is a smooth fade-in, peak, fade-out rather than a meteor's quick rise and slower fade.

This site will give you a prediction for your location of when you can see them.

Apparently these five art are part the next generation of Iridium satellites and they are not expected to create the same predictable flares as the previous generation did when their solar panels caught the sun at the right angle. As a result, another batch of the older Iridium satellites will be either moved to parking orbits that are not so tightly controlled with less predictable flares where they can act as backups, or possibly even de-orbited outright. Predictable Iridium Flares are currently expected to cease altogether by the end of the year, so last call, I guess...

heavens-above.com shows it as about 5 to 8 mag over my location for the next set of passes (see 9 Mar - 19 Mar) http://heavens-above.com/PassS... Which is hardly "the brightest thing in the sky other than the Sun" and not even naked eye visible at all even at 5.0 mag if you're at a light polluted area. It's possible the heavens-above estimate is low for the magnitude? Your plain old LEO satellites will beat these magnitudes all the time, I've seen many from the dark skys of Nebraska when I was there in an astronomy club. But you had to look right at dusk when the sky was just getting dark but so the Sun was still hitting the satellite. The Humanity Star will go dark just like any other LEO sat because it goes into shadow so quickly due to the low orbit.

No idea why anyone is upset. Sure, if you start putting dozens of disco balls in orbit there might be an issue, but this one you can't even see! When they say "bright" they mean that once every quite a few days it might pass above you in just the right orientation and angle from the sun so that one of its mirrors hit you directly during the night with sunlight at a maximum brightness of... magnitude 4.2... If you don't know what that means, it is about as bright as the stars in the middle of the little dipper "handle", the ones you can't see from the city. So cities are out, rural areas can see it, but still it is nowhere as bright as other satellites, ISS etc.
In any case best data for when/how bright: heavens above.

X37-B does have cross-range capability, but not enough to evade people tracking it from the ground. http://www.heavens-above.com/ will show its location and orbit shortly after launch.

After launch, go to http://www.heavens-above.com/ to see exactly when the X-37B will be overhead and visible.

I've seen it too., thanks to Heavens Above. http://www.heavens-above.com/

There is still atmospheric drag at the ISS's altitude. You have to boost it regularly to keep it in orbit.

Here's a graph of the altitude of the ISS. You can see the boosts, followed by a slow decay until the next boost.

The ISS gets regular orbital boosts to stay in orbit. So yes, the whole assembled station is designed to handle acceleration.

Here's the mean altitude of the ISS: http://www.heavens-above.com/I...

The large vertical jumps are when a resupply ship thrusted it to a higher altitude. (I don't know what's up with the data point in January)

While we're talking Iridium, they produce the brightest satellite flares, which can be rather striking. The website Heavens Above even has a helpful page where you can see when and where they are visible.

This comet is moving at 46 km/s:
http://www.heavens-above.com/c...
Earth is moving at 30 km/s, so that is a difference of 16 km/s, or approximately 36k miles/h. Good luck making anything that can survive that kind of impact.

At 200km the air pressure is about 100 million times less than what it is over here. That is enough to have a reasonable decay rate of weeks/months/years. "skylab" came down after a few decades, right?

Depending on the satellite's drag and ballistic coefficient, below around 200km you're talking hours to days, at 300km - days to weeks at the outside. Unboosted, anything between (roughly) 300 to 350km is essentially gone within a year. That's why Skylab was and ISS is, higher still - in the 400km range.

Skylab's second stage (seperated after the station was in it's final orbit) re-entered after only two years, while the station itself was reboosted on several occasions by docked Apollo spacecraft. Skylab's post occupation lifetime was extended by giving it a larger than normal reboost before the final manned mission departed, and subsequently by carefully maintaining it in a low drag orientation.

The ISS requires regular reboosts to maintain altitude.

Create an account at Heavens-Above to get time and direction to see space objects. http://www.heavens-above.com/ It's a great resource.

When I first heard about this (or a similar project), I hoped it would be something like this: iridium flare tracker, i.e. that it would point to the object of interest with a nice green laser pointer, nut just quietly blink in a corner. Nowadays, a RasPi, a GPS module and two servo motors should be enough to implement this, and it should be within the 150$ budget. Add a few $ for a display and possibley buttons / joysticks to pick anything heavens above deems interesting, or identify things.

Anyone who has ever looked at the night sky might goto H-A and create an account.The site has much info. I saw the Shuttle chasing the ISS in orbit over my home, many satts like TRMM and China's Tiangong !, spy satts like the Lacrosse series passing by. Most of what can be seen is space junk, rocket bodies and such, some have been in orbit for twenty years. The X37B, seen that too. I was at work and saw Shuttle Columbia on it's fateful re-entry.... RIP brave souls. http://www.heavens-above.com/m... http://www.space.com/25275-x37...

The New Scientist article indicated the difference was between 0.005% and 0.008%, which means the effect is fairly small. At the ISS approximate orbital speed of 17,150 mph, this would be a difference of 0.4 to 0.7 mph. At geosynchronous distance, it's more like 0.025 to 0.04 mph (out of ~1000 mph). Satellites in orbit already have to deal with Earth's non-spherical gravitational field, and anything in LEO loses speed due to atmospheric drag. The ISS has to boost its orbit periodically to stay at the proper altitude.

Furthermore, the anomalies that led to the theory were occasional changes in velocity not explained by these other known factors. Some things like relativity and Sun+Moon weren't factored in but aren't considered likely to completely account for the observed discrepancies.

I like the idea of a cloaked fleet of spaceships. Keep your towel handy.

The info's out there, just not in these articles. For the northern hemisphere it'll be above the horizon in the east before dawn and (as December progresses) in the west after sunset. You won't get text alerts for a comet (time-insensitive, unpredictable) but Heavens Above, my preferred satellite-flare web site, will give you simple "where-to-look" instructions for ISON. You're better served by getting one of the many excellent astronomy smartphone apps; I use Star Walk but Distant Suns is also very popular. They're expensive as apps go but they're totally worth it.

Happy hunting!

The info's out there, just not in these articles. For the northern hemisphere it'll be above the horizon in the east before dawn and (as December progresses) in the west after sunset. You won't get text alerts for a comet (time-insensitive, unpredictable) but Heavens Above, my preferred satellite-flare web site, will give you simple "where-to-look" instructions for ISON. You're better served by getting one of the many excellent astronomy smartphone apps; I use Star Walk but Distant Suns is also very popular. They're expensive as apps go but they're totally worth it.

Happy hunting!

Let's also not forget that North Korea successfully launched a satellite into a stable polar orbit (higher than the ISS). That first payload was a bit of a dud, but they have a proven ability to send a package over any part of the Earth's surface.

It's not really the position, it's the signal strength. In low Earth orbit the orbit can be (and routinely is) determined from radar and optical observations without any cooperation from the spacecraft at all. The dish at Perth is 15 meters. At 10 cm wavelength, it has a beamwidth of order 7 milliradian, so at 300 km range they need about 2 km orbital accuracy for pointing, which should be easily achievable.

Note, from the same ESA press release :

In the past few days, ESA's 15 m-diameter Perth dish was modified by the addition of a 'feedhorn' antenna at the side of the main dish so as to transmit very low-power signals over a wide angle in the hopes of triggering a response from the satellite.

This wasn't about pointing the antenna, it was about lowering the signal power. The omni-directional antenna on the spacecraft is intended for use in deep space and was probably being saturated by full power blasts from regular tracking stations. It needed to be "tickled" by something weaker.

Kudos to ESA for doing this. You can bet this was a major effort at the ground station. The feedhorn receiver was probably jury-rigged from spare parts, and probably took days of round the clock work to install and get operational.
 

The probe was never lost. It is a large object in low Earth orbit; its trajectory is known perfectly well. (Right now it appears to be over Tahiti, for example.)

What it was was uncommunicative. A spacecraft that says nothing is essentially hopeless, unless you want to send someone up there to grab it. Now that it is talking, there may be a chance to save the mission.

Another news story totally lacking facts.. Why can't any news organization list the ground track of any of these? Knowing if it geosynchronous, geostationary, Polar, or other orbit can list the maximum latitudes this craft will reach. They make me do the research myself. The ground track is listed here;
http://www.heavens-above.com/orbit.aspx?satid=20638&lat=50.733&lng=7.100&loc=Bonn&alt=57&tz=CET

Northern Siberia, parts of Alaska, Greenland and Antarctica can't be hit by this. Saying it can come down anywhere is FALSE.

http://www.heavens-above.com/
Enter your coordinates (requires a login, otherwise it's 0 degrees N / 0 degrees E) and look for the X-37B link under "Satellites".

Be sure to check out Space Weather's Flybys page or Heavens Above to see if the ISS and Discovery are viewable overhead in your neighborhood. I tried a few zip codes and it looks like the NYC area will get to see a very bright ISS and Discovery pair on March 5th. This will be the day that Discovery undocks so you may get to see two bright dots moving across the sky from that area. I had the opportunity to see the ISS with Atlantis recently undocked on STS-129 and it was an impressive sight.

The rate of orbital decay is highly dependent on the surface area to mass ratio of the object. Typical debris has little mass and a lot of surface area, so it decays very rapidly when compared to a satellite or other massive object. This PDF explains it well, and you can look at TLE files to get a feel for actual decay terms.

The EGRS-3 Sat launched in 1965 is still orbiting in an 894 x 927 km orbit. TIROS-1 was launched into a 693 km x 750 km orbit in 1960, and is still merrily orbiting away 51 years later at 638 x 672 km.

The oldest sat still in orbit is Vanguard-1. It was launched into a rather elliptical orbit with the perigee near 650 km, but only massed 1kg!

The rate of orbital decay is highly dependent on the surface area to mass ratio of the object. Typical debris has little mass and a lot of surface area, so it decays very rapidly when compared to a satellite or other massive object. This PDF explains it well, and you can look at TLE files to get a feel for actual decay terms.

The EGRS-3 Sat launched in 1965 is still orbiting in an 894 x 927 km orbit. TIROS-1 was launched into a 693 km x 750 km orbit in 1960, and is still merrily orbiting away 51 years later at 638 x 672 km.

The oldest sat still in orbit is Vanguard-1. It was launched into a rather elliptical orbit with the perigee near 650 km, but only massed 1kg!

I've never taken a serious interest in astronomy but on a few drunken star-gazing nights I've seen a few fast moving lights. I'd always put them down to "shooting stars" without giving it much more thought. While they were UFOs to me in the sense I couldn't identify them I recently discovered the site http://www.heavens-above.com/ that has excellent satellite pass predictions.

I set up a tripod a few weeks ago and took a photo of the ISS as it passed over at a good azimuth and altitude. It really suprised me how bright it was both in the image and to the naked eye. Now I often look at the site and wander out the back for a look at appropriate times. Depending on the background terrain and path it's taking I can see how a lot of man-made satellites could be mistaken for something extraterrestrial.

While NZ of course have an airforce I'd doubt there's a lot of cutting-edge new tech being developed there, but their clear skies and southern location would make it a good location for viewing those sort of passes. Much like here in Tasmania that's only a little further north.

I was wondering the same, as well as if they would be a predictive as the current ones. My 6 YO enjoys seeing them so we check the schedule at heavens-above.com regularly for bright ones at "reasonable" times.

Indeed right now all the planets (in our Solar System) are on this side of Saturn. Of course, only two of these can ever be on the far side of it from us. That's right, I'm not counting Pluto as a planet.

No, the business plan worked as designed. Motorola conceived Iridium as a way to sell a lot of equipment, for which they made a huge profit, while at the same time they had very little financial stake in Iridium actually succeeding.

That's utterly incorrect. Motorola lost about three $billion on Iridium: http://www.heavens-above.com/iridiumdemise.asp

I am a graduate student in astronomy and I am very active in astronomy education and outreach. There are a lot of things you can do with students with a very small set of tools. In addition to your telescope I would either bring or encourage students to bring: 1. Binoculars 2. Flashlight (red led OR take a regular flashlight and cover in several layers of red cellophane) 3. an open mind If you then bring the Astronomical Almanac and a planisphere (star chart) you can find many of the great objects in the sky. Looking at bright stars that have different colors is a great way to start talking about what's in the sky. Betelgeuse and Rigel are great for this and they are up at the right time of night in the spring. Another great binary star is Alberio in Cygnus. It is a double star that is a K spectral type and a B spectral type (orange and blue in color). You can see them through binoculars so it should not be hard to point the telescope at it. Almost all of the Messier catalog objects should be visible with a 4-inch telescope even if they are not magnificent. This may be a way of talking to students about how a telescope works and why astronomers want better cameras and bigger mirrors. If you have students learning some of the objects in the night sky and able to point to them with and without a telescope I think you will be doing well. http://www.heavens-above.com/ is a great website that will tell you about all fly overs of the space station, Hubble, and any iridium flashes. Some of these flashes are quite spectacular. While you cannot see these in the telescope they are fun. As for planets, no matter what telescope you use none of them are truly spectacular. As the aperture grows the amount of detail you "can" see will go up because you are collecting more light but the atmosphere will blur the images more as well. So it is a toss up at some level. I love looking at solar system objects just to see what I can see. The moon is fascinating and you can make good use of the night/day boundary to teach about mountains, shadows, and how Galileo proved the moon is a flawed object. But really my advice is to try it and look up with your students. Best of luck!

• Satellite watching
• heavens-above for local ephemerids
• Iridium flares
• Rocket Boys
• Sputnik

Download a starmap application or I guess there are some online so you know what's up there and when.

Go to the Heavens Above site http://www.heavens-above.com/ and do the free registration. It will let you set and save your location for subsequent use. Then you can display current star maps so you can see what's in sight whenever you want.

The home page is a bit jumbled, so you'll have to look for the Register and subsequent Login links, but it's worth it.

One thing I'd suggest is to have the kids register so they can use it i the future. It has links that will let you generate tables of visible satellite passes, including the International Space Station and shuttle passes. I've only watched a couple myself, but it's really impressive to watch an ISS pass at night. The speed with which it moves across the sky is surprising the first time you see it.

I haven't yet caught one, but the flares off of Iridium satellites would also be worth looking for. By registering, interested kids will be able to look for these things on their own long after your class unit is done. I think that would make for a much more satisfying experience (for those ready for it) as an ongoing resource for their own exploration, as compared to the one-time experience your necessarily limited schedule would allow.

I'd also encourage the kids to look frequently at NASA's Astronomy Picture of the Day (APOD) http://antwrp.gsfc.nasa.gov/apod/astropix.html -- truly astounding and gorgeous pictures daily and likely to pique a deeper interest in the subject.

Best of luck on this worthwhile project.

Only problem I foresee is that with a 4" telescope, unless there's some kind of tracking mechanism, regardless of what you're looking at, cycling through a bunch of kids will be difficult as the object/detail in question will have moved and the telescope will need to be constantly re-pointed. THAT will be the toughest part in my opinion. You can reduce the problem by paying close attention to the pivoting mechanisms on the telescope (possibly with some dry runs without the kids) so that the one axis points to celestial north and the other along the celestial plane. If you're tracking the moon or Jupiter, then a turn of only one of the knobs (this thing does have a tracking mechanism, right?) will keep it in the scope.

Cue the piling on as I'm sure my description is un-artful and /. is an unforgiving crowd.

As well as all the previously mentioned objects (moon/planents/etc.) you could consider man made stuff as well including ISS, satelite 'flashes', radio beacons from satelites.

There's a real time 'calculator' here:
http://www.heavens-above.com./

These would help you students understand orbits.... even just a simple GPS reciver which shows which satellites are above you would be cool.
Mungewell.

Show her the star whose distance in light years is approximately equal to her age. The photons reaching our eyes left that star the year she was born. This revelation is always followed by a moment of silence, misty eyes, or a quiet "wow". After tickling her brain, hugs & kisses come easily...

Here's a cheat sheet to help you select the right star: http://en.wikipedia.org/wiki/List_of_nearest_bright_stars and here's a site to help you locate the chosen star: http://www.heavens-above.com/ (use the constellations page & the whole sky chart).

Next year, she'll be a year older, and it will be a different star. We sometimes do this on her birthday.

Off the top, I'd tend to recommend it for kids that are a bit older than the seven- to nine-year-olds in the original question. Much of astronomy requires a certain amount of patience - waiting for your eyes to get dark adapted, learning the locations of stars and constellations, finding objects to look at, using Heavens Above, etc.

I'll echo what some others have already pointed out -- a cheap plastic Wal-Mart MAGNIFIES STARS TWO THOUSAND TIMES!!! special is a recipe for frustration and heartache. What matters is aperture (diameter of the main lens or mirrors - the amount of light you collect goes up with the square of the diameter) and quality optics. A crappy mount or tripod means images that jiggle and difficult pointing.

Another point to bear in mind is that (in much of the northern hemisphere mid-latitudes, at least) you're going to be in the dead of winter. It's going to be cold, overcast, and wet or snowy for much of the next few months. Consider the challenges of manipulating telescope components and assembling tripods while wearing gloves. If you do give a telescope to a loved one, do be considerate of their personal comfort. Freeze the kids once and you may snuff out any further interest in astronomical observation.

Finally, consider that a telescope may not need to be the first thing on the list. A smaller spotting scope, monocular, or pair of binoculars can introduce a lot of astronomical sights, and often offer good-quality optics and rugged construction at much more reasonable prices. The surface of the moon is fascinating even with a low-powered scope, and any good pair of binoculars will reveal the Galilean moons of Jupiter. Binoculars and small spotting scopes can often be mounted on a conventional camera tripod or even be hand-held; this makes it much easier to pick them up and go outside on a whim. They're also useful for watching everything from wildlife to baseball games -- meaning that even if you don't manage to kindle interest in astronomy, the gift still can still be put to good use. ~~~~

The ISS is usually only visible for a few minutes, between 5 and 10 if you are lucky. But for anyone interested in trying: http://www.heavens-above.com/ Don't forget to give it your location.

It's been mentioned here in the past, but what would combine the awe and excitement of a 'stunt', along with the progress of science, would be to establish a manned space station/city. It can be fairly near the Earth at first...

you're in luck! We got one. In orbit now. You can see it yourself

(That was, of course, Wehrner von Braun's view, too)

As Eternauta3k said, but this is the exact link:
heavens-above.com

Here's the link http://www.heavens-above.com/ Basically you put in where you live and it tells you the times for the next few days. Plus it even generates a map of the stars at that point in time and shows where to look for the ISS.

Just use Heavens above.

This is the website where you find the latest sighting opportunities for your location.

http://spaceflight.nasa.gov/

Go to +REALTIME DATA / Sighting Opportunities then, choose your country and the rest should be self explanatory, at least for the United States which is all I have used this website for :)

I prefer this site, which has an Iridium Flare calculator as well:
http://www.heavens-above.com/

I live in Israel. Will I still "have at least a few opportunities to see the biggest spaceship ever built"? Actually, yes, but not because of the US flyovers:
http://www.heavens-above.com/PassSummary.aspx?satid=25544&Session=kebgfgfichcdapnnagjfnaip

Here's a good resource for ISS, Iridium flares, etc predictions: http://www.heavens-above.com/

Set you location in the configuration section and it will give you the time, date, altitude, and azimuth for Iridium flares. The ISS coordinates are a little more vague, but it tends to be visible a little longer.

Another source for flyby times for the ISS and more. Plus, no java required. http://www.heavens-above.com/

Hubble and Herschel's orbits are not even comparable to each other.

As pointed out earlier in a separated thread, Hubble is in a low, circular orbit about 560 km above the Earth. It has has a low inclination -- about 28 degrees with respect to the equator. You can actually see the orbital details and where it is in the sky on Heavens Above. The low Earth orbit was chosen so that the space shuttles could service it as they can't reach very far orbits basically due to limitation i how much fuel they can carry (bear in mind that at launch the shuttle engines are powered by the huge orange tank attached to it). It would have to be double checked but I think that the low orbital inclination was decided because it's was easier to launch -- Hubble is one of the most massive payloads ever carried by a space shuttle -- since you benefit from the fact that the Earth rotates so it effectively adds up to your velocity whereas for a polar orbit the contribution is basically null.

On the other hand, Herschel is orbiting 1.5 million km away from the Earth at the L2 point, in a direction opposite to the Sun -- the Sun - Earth - Herschel system forms a straight line. To give you an idea of the scale, the Earth-Moon distance is about 385 000 km so Herschel is located 3.9 times further. Therefore it's easy to understand why the mission is a one-hit wonder because there is no way someone is gonna go there fix it. To be more precise, Herschel is actually "orbiting" about the L2 point (see this diagram on Wikipedia) otherwise its orbit around the Sun-Earth-Moon system would be too unstable. The main reason for sending Herschel so far away from Earth is to optimize its infrared performances. Herschel observe at very long infrared wavelengths compared to, say, the the infrared camera of Hubble and near the Earth, even though you are in space, there is still a lot of thermal radiation coming from the Earth as well as the radiation belts that add up on top of what you want to detect. By being further away, passive cooling helps you and the liquid helium that keeps you cryostat cold heats up slower so your instrument has a longer life time. Also, "temperature" fluctuations are much smaller out there whereas they can be quite large near the Earth depending if your in the Earth shadow, crossing a radiation belt, etc. More stable environment means smaller systematics, which, in turns, imply better telescope sensitivity.

Finally, note that Hubble's successor, JWST will also hang out around L2 for similar reasons.

Well, you're right there. I didn't have any sutures, but I do see halos around very bright objects. I'm not sure that's a result of the surgery or something that was always there but out of focus.

One of my hobbies is observing satellite passes, and I don't think my dark-adapted vision has suffered, but I hadn't thought about it until you mentioned it.

PS - If you're interested in observing satellites, http://www.heavens-above.com/ is a great site.

The furthest traveled object (Voyager 1) has gone for over 30 years with very high speed and has not even left the planetary system yet (it is around the distance of Eris, ~110AU), not to mention Heliopause [1,2].

Here is your flight map though: http://en.wikipedia.org/wiki/File:Solarmap.png (note: logarithmic)

Can we ever overtake this? Good luck getting a object faster than Voyager 1.

[1] http://en.wikipedia.org/wiki/File:Voyager_1_entering_heliosheath_region.jpg
[2] http://heavens-above.com/solar-escape.asp?/