Two starry questions

Hi everybody,
While walking home, just now, I got a good view of a very starry sky.
As I'm out in the country with no street lights, I could see an object in the sky racing across at enormous speed.
If it was stationary it would look like a normal distant star.It was very dim and just a spec.
What was this?
Secondly to the East/south east, there was about a third of the way up from the horizon a Very bright object which looked like a very lit up cross, but so tiny obviously as to barely make out that shape, what was that?
Sorry, if these sound like dim questions, I'm just curious.
mm

Saruman

The first was obviously either a Satellite or maybe it was the ISS. I have never seen the ISS, no wait.. i think i have.,. A Satellite would look like a small star moving. The ISS would blaze across the sky and be very bright.

As for the other one... It might have been Mars.. sounds like the right direction and if it was half way up in the sky it might have been after midnight and i think thats about the right place.. Its very bright right now as its on its way to its clossest pass in 60,000 years

Sev

Well, as Saruman said, youre first observation was most likely a satellite. As far as im concerned, the ISS is a satellite. If it was the ISS, youd be seeing something traverse the sky at roughly the speed of a distant overhead airliner, and it would be about as bright as the brightest star visible in the sky at that time. Most other naked eye satellites that aren't ISS and weren't mir, would look the same, just much dimmer.

There are satellites up there all the time, constantly crossing our heads, with a pair of binoculars and the right information, you could probably spot one every minute. However its only the ISS these days (or the space shuttles when theyre on missions) that are any way bright enough to stand out to the casual observer who just happens to take a quick glimpse of the sky.

If youre any way more interested, there is good software you can download to track and plot satellite crossings. But if you're lazy like me, visit this site : http://www.heavens-above.com/

It's really really good, just set it up with your longitude/latitude (it has most cites/towns on file anyway) And youre only a few clicks away from getting a list of most naked eye observable (mag +4.5) satellites going by each night.

But the real eye openers are what are called 'iridium flares'. These are a special case of an ordinarily dim fleet of satellites in which one of their radar antenae directly glints back the light of the sun and they appear to 'flare' up momentarily getting very bright indeed. Of course how bright they get depends on how coincidentally perfect your location is for the event. There's at least one of these a night these days, but you get a near perfect line-up only about once a week which produces a very bright magnitude -7 or -8 (or sometimes -9) flare.

If youre in and around dublin theres two bright ones coming up in the next day.

05 Aug 04:38:23 -8 61° 272° (W ) 0.9 km (E) -8 Iridium 68
05 Aug 21:33:24 -7 29° 345° (NNW) 2.3 km (E) -7 Iridium 29

First one's a bit early tho Second one might be worth taking a look for. A third the way up in the sky, roughly north.

What I love about it tho, is that if you accurately set your watch, to an international standard, like the USNO atomic clock (you can do it off the web) you can time these events down to the nearest second. I've always awaited the occasion that I could be walking in town with a few people, point up at the sky, count down from 10 to 1, and have a flare appear exactly as it should. It's interesting stuff. Anyhow thats the end of my rant, if anyone's anyway interested after all that, you'll find this time of year is best for satellite observers.

Sev

As for you're second query. I'd probably go with mars too, of course it should just appear as a normal every day star, except for the fact its very bright. It's orangy-reddish colour however is very apparent, and could explain the 'burning'. As for a cross? Could be just your eyesight producing that effect on a star that is brighter than normal. Or maybe because it is warped and scintillating because its low on the horizon? If it was Mars it fits in with it being 2 am in the morning, it would have been about 25 degrees off the horizon, and due south.

Thanks for that Guy's.
There was actually a plane in the sky aswell travelling west which appeared to be going only a fraction of the speed of the dim star like object.
The star like object was following the curve of the Sky from south to North and was as dim as any of the rest of the stars.
From what you are saying then, this object could have been travelling at the same speed as the plane, but just appeared to be going much, much faster because of it's height?
I was kind of merry at the time and did wonder ( only for a second now...) was someone finally coming to collect me:D

From what you both are saying, the extremely Bright object must have been Mars, as what I would have associated with being East SouthEast normally would have been at that time the Southern Sky?
mm

wolfman

Originally posted by Sev
Anyhow thats the end of my rant, if anyone's anyway interested after all that, you'll find this time of year is best for satellite observers.

Sev

Just wondering? Why is this time of the year best for satellite observers

Sev

Well, I could be wrong about this actually, that was said from my own experience. But from just calculating my own satellite passes on computer, I seem to find a lot more viewable satellite passes in the Summer season than I do in the winter. And I'll give you my own reasoning for it.

Well, the reason you can see the satellite passes in the first place, is because while were on the ground in the shadow of the planet, and in darkness, the satellite from its position high above the earth is still being bathed in sunlight. Therefore, most satellite passes should be visible not long after sunset while the potential visible satellites havnt entered shadow right? I figure that in the summer time, having shorter nights, is going to increase that window of time to observe satellites, extending it right through midnight and to morning. Whereas in the winter, satellites would only be visible at a specific time in the evening and in the morning, when the angular position of the earth in relation to the sun is such to accomodate the viewing of overhead satellites. But correct me if im wrong.

wolfman

Sounds good to me!

wolfman

Just went outside to view one of these about 15 minutes ago. Not a thing!

I DID see the ISS a lot a couple of weeks ago. Very easy to spot.

Should I be able to see the Iridium Flares with the naked eye?

I presume so, going on what Sev posted earlier. Any help appreciated

Sev

Yeah, the iridium flares get brighter than any other satellite in the sky. Provided your watch is set right, the sky is clear, and the orbital elements from which you calculated the pass are accurate, then you should see them. I called a few friends out of a poker game the other night to see one at 01:15am. They were more impressed with the fact I could do a countdown from 10 to the event than the event itself (It was only -3 magnitude).

It's important you know where in the sky to look. I usually find the times for the flares from the heavens-above.com website (its convenient and trustworthy) and plot the path then of the satellite with 'satspy', the satellite software I use. I then mark off the time of the flare on the path of the satellite to get an idea of what constellation or star its passing when it flares. Although if you have a compass and a good sense of angular distance, you should do ok. Although, the annoying thing is that the flares only last at most 10 seconds, they get brighter and brighter, reach maximum brightness, then dim down again just as quick. So if youre looking in the wrong area of the sky, it can be easy to miss.