Slow moving object..very curious what it was...

[Pablo3uk]

Kind of new to this, but was looking at Venus through my ES 24mm 82 eyepiece tonight in South East London and at 8:48pm saw a very slow moving object moving below it through my whole field of view for about 60 seconds without moving my scope....I've only ever seen what looks like satelites that move through very quickly, so am very curious what this object may be...any ideas? Do asteroids move like this?

[Mr Spock]

It will be a satellite, probably a distant one. 

[Leo S]

On 02/04/2023 at 21:14, Pablo3uk said:

Do asteroids move like this?

Short answer is, yes, they can do, but as Michael says, more likely you caught a satellite (or perhaps even something else).

Most asteroids are very very dim, and only become very dim as they approach Earth (in their last few hours before a close approach/impact), so they are quite hard to spot in comparison with relatively brighter objects like satellites. The pros and dedicated amateurs are starting to find small asteroids a few hours before impact now. There have been 8 asteroids so far that were found prior to impact, and the last was just a couple of months back, with an atmospheric entry that was over The Channel/French coast and visible from the UK (if you were lucky enough to have been in one of the few places that was not totally clouded out).

Regarding how fast they move, keep in mind that the closer they are, the faster they will appear to move, and in their last 10's of seconds (assuming impact) they can travel at quite a pace. Here are two examples my cameras caught last night for example - one two.

Also keep in mind that perspective plays a large part in how fast an object appears to travel across the sky. For example, asteroids typically enter the atmosphere at relative velocities of between 10 to ~50 km/s. At the higher end, an asteroid entering the atmosphere at 50 km/s, at a very low angle of entry (we call these "earthgrazers" because they graze the atmosphere at low angles and usually don't penetrate deeply), might cross the entire sky, horizon to horizon, in perhaps 12 or 14 seconds.

On the other hand, if the same object had hit the atmosphere at a high angle instead, and lets say you are observing from just the right spot on Earth, so that it's heading directly towards you. In that case, you would observe what would appear to be a stationary star quickly brighten, then become extremely bright before hopefully disappearing without vaporizing you. No apparent movement, because you can not see it from that particular perspective. The technical term for it would be a "point-fireball".

The other thing I would add is that other objects could potentially appear similar in behavior (aircraft, etc) so it's not always a given. My standard advice is to always try to record the sky, so if you observe something you can't easily identify initially, you record should help you work out what it is. Position, direction of travel and accurate timing are always useful to help identify an object, and these would all (except perhaps "timing", depending how you are recording) be recorded for you. The other plus, if you do this regularly, is that you may catch the occasional slightly larger asteroid entering our atmosphere, or something else unusual!

 

[Grogfish]

According to SkySafari, satellite Starlink-2044 passed through your field of view at that time. Direction of travel would have been from the horizon upwards towards zenith fairly close to vertical.

Starlinks do zip past pretty quick though. Not sure what scope you used, but I think 15s sounds more likely.

You don’t say what direction of travel of the object was but if it was pretty horizontal then I wouldn’t immediately rule out a distance plane or helicopter; it may not have been its lights you saw (too distant to its see red/green flashing lights) but just sun reflection which is why it looked like a space object.

<I’ve edited this bit as a realise I was out 180degrees first time around!!!>
From South London, there will be lots of flights going into Heathrow. Because they’re actually heading towards you they’ll appear to move relatively slowly horizontally in your field of view. Though guessing you’d be used to these. If you are really properly South then there was a flight from Vigo to Stanstead that was at 18’000ft over Cobham- which would have been going South-> North/ left-> right in a correct view scope This said you’re in some of the busiest airspace in the world and there were many flights going on.
 

… just shows how busy the skies are…

Edited April 9, 2023 by Grogfish

[Stu]

I suspect this may have been a geostationary satellite. Whereabouts in the sky were you looking?