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Old 02-07-2020, 01:52 AM
Dart77
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What Star is That Please? (Perth)

Hi There All, my first post and I just joined to see if anyone here could identify an interesting star I often see - from a description. Please excuse my layman's terminology! I'm in Perth and I am not an astronomer and I don't even have any binoculars or a telescope. But I am always out at night and more often than not I have my eyes angled up towards the heavens in wonderment.

I often see this star, I don't think it's a planet as it always seems to follow a similar path. I have looked at Stellarium and tried to see if that would identify it using the approximate time within minutes, the day, setting my location etc. But I can't see anything that resembles this beauty in that position.

I live near Perth Airport and so am used to seeing lots of aircraft in various far positions approaching and leaving. Anyone used to seeing large airliners at night would look at this star for a few seconds and more than likely say it's a distant jet. Because that's how it appears.

Anyway, here is the description:

Last few months, around 8.15 to 8.30pm it is seen low in the SSW sky, quite bright, and by around 1am it has arced up higher to be in the West, right over where the sun sets and more noticeable than earlier. It has a strange squashed shape, longish, which led me to think it might be Sirius, as I read that Sirius is a double star? It gives off a bright white but sometimes slightly bluish light with occasional bright red and other colours such as green seen as well. It is quite mesmerising to watch. And the squashed shape is unusual to my eyes.

Has anyone got an idea of which distant Sun this is? On Stellarium, Sirius was not near the position I see this.

Thanks.
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Old 02-07-2020, 05:12 PM
phomer (Paul)
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Quote:
Originally Posted by Dart77 View Post
Hi There All, my first post and I just joined to see if anyone here could identify an interesting star I often see - from a description. Please excuse my layman's terminology! I'm in Perth and I am not an astronomer and I don't even have any binoculars or a telescope. But I am always out at night and more often than not I have my eyes angled up towards the heavens in wonderment.

I often see this star, I don't think it's a planet as it always seems to follow a similar path. I have looked at Stellarium and tried to see if that would identify it using the approximate time within minutes, the day, setting my location etc. But I can't see anything that resembles this beauty in that position.

I live near Perth Airport and so am used to seeing lots of aircraft in various far positions approaching and leaving. Anyone used to seeing large airliners at night would look at this star for a few seconds and more than likely say it's a distant jet. Because that's how it appears.

Anyway, here is the description:

Last few months, around 8.15 to 8.30pm it is seen low in the SSW sky, quite bright, and by around 1am it has arced up higher to be in the West, right over where the sun sets and more noticeable than earlier. It has a strange squashed shape, longish, which led me to think it might be Sirius, as I read that Sirius is a double star? It gives off a bright white but sometimes slightly bluish light with occasional bright red and other colours such as green seen as well. It is quite mesmerising to watch. And the squashed shape is unusual to my eyes.

Has anyone got an idea of which distant Sun this is? On Stellarium, Sirius was not near the position I see this.

Thanks.

Dart77,


You aren't going to find it in any planetarium program as anything outside the Earth locale is going to set when it is in the West not rise higher as the night progresses, unless it is far south.


Are you sure of your Cardinal directions, as Jupiter is bright in the East and rises? It may be the moons, atmospheric distortion or your eyes that make it appear slightly elongated.



Paul
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Old 02-07-2020, 05:27 PM
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The Mekon (John Briggs)
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Canopus perhaps?
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Old 02-07-2020, 05:46 PM
Wilso (Darren)
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Down load SkySafari app on your phone, it’s a useful tool for identifying objects in the sky. All you have to do is lift your phone up and the camera does the work! Enjoy
Oh and welcome!
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Old 02-07-2020, 06:27 PM
Dart77
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Originally Posted by Wilso View Post
Down load SkySafari app on your phone, it’s a useful tool for identifying objects in the sky. All you have to do is lift your phone up and the camera does the work! Enjoy
Oh and welcome!
Thanks for the reply and welcome, Wilso. I don't have a smart phone and don't intend to get one either but I have seen the program you mean or one like it and yes it is quite an amazing piece of technology.

If there are any Perth astronomers who read the post, they may well know the one I mean from the description, as it is very noticeable.

I will look up Canopus and see what it says about that.
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Old 02-07-2020, 06:34 PM
Dart77
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Originally Posted by phomer View Post
Dart77,


You aren't going to find it in any planetarium program as anything outside the Earth locale is going to set when it is in the West not rise higher as the night progresses, unless it is far south.


Are you sure of your Cardinal directions, as Jupiter is bright in the East and rises? It may be the moons, atmospheric distortion or your eyes that make it appear slightly elongated.



Paul
Thanks for reply Paul, yes I double checked the directions and at that time I said in the OP it is in between S and SW and is higher in the West around midnight. Could be atmospheric distortions I suppose, but it's the only star that is that shape in that area or in many other areas as well. Every time I see it it is the same.

Last edited by Dart77; 02-07-2020 at 06:35 PM. Reason: typo
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Old 02-07-2020, 07:34 PM
Hemi
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Hi Dart,

Welcome, as Paul has said, any celestial object west of south is on its way down, so a star almost at the horizon at 8pm won’t be higher in the west at 1am.

It can’t be Sirius, from your location description and essentially rises and sets in the daytime this time of year. It looks like a pin point star in most telescopes, so won’t appear squashed to the naked eye because of its tiny companion.

It can’t be Canopus, as it has set by 9pm, it’s interesting though as you can see it again same night, as it rises at 3am but in the SE. again wrong time and location from your description.

Are you continually observing from 8pm to 1am? If not then I suspect you maybe looking at two different objects that you think are the same. It’s very easy to do, if your not familiar with the night sky and how it works. If the sky is not great for seeing, then the stars will twinkle away in all manner of shapes and colours.

Pity about the smart phone, as it will answer your question, maybe you could borrow one. You could try to print out a star chart from the internet.

Happy investigating.
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Old 03-07-2020, 03:00 PM
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The_bluester (Paul)
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Another option would be to install Stellarium on your PC, you can then set your location in it's settings, adjust the observation date and time to match when you saw whatever it was, and have a look at what might have been visible at that time. As others have said, anything low in the SSW at 8:30PM will not be higher in the west at 1AM. If it is close enough to the pole that it does not set, it will rotate around the to be more toward the SSE as the night goes on. It might be two different objects.

I can't comment on anything visually elongated, individual stars are really pinpoints visually, even in a telescope.
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Old 04-07-2020, 12:33 AM
Dart77
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Originally Posted by The_bluester View Post
Another option would be to install Stellarium on your PC, you can then set your location in it's settings, adjust the observation date and time to match when you saw whatever it was, and have a look at what might have been visible at that time. As others have said, anything low in the SSW at 8:30PM will not be higher in the west at 1AM. If it is close enough to the pole that it does not set, it will rotate around the to be more toward the SSE as the night goes on. It might be two different objects.

I can't comment on anything visually elongated, individual stars are really pinpoints visually, even in a telescope.
Thanks Paul, yes I did that as you suggested with Stellarium but could not see anything similar. Due to my inexperience it could be two different objects yes, but the size and uniqueness of shape and colours that I have not seen in that part of the sky suggested to me that it is the same thing. Interesting though about the rules of rising in relation to the position etc.
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Old 04-07-2020, 12:50 AM
Dart77
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Hi Dart,

Welcome, as Paul has said, any celestial object west of south is on its way down, so a star almost at the horizon at 8pm won’t be higher in the west at 1am.

It can’t be Sirius, from your location description and essentially rises and sets in the daytime this time of year. It looks like a pin point star in most telescopes, so won’t appear squashed to the naked eye because of its tiny companion.

It can’t be Canopus, as it has set by 9pm, it’s interesting though as you can see it again same night, as it rises at 3am but in the SE. again wrong time and location from your description.

Are you continually observing from 8pm to 1am? If not then I suspect you maybe looking at two different objects that you think are the same. It’s very easy to do, if your not familiar with the night sky and how it works. If the sky is not great for seeing, then the stars will twinkle away in all manner of shapes and colours.

Pity about the smart phone, as it will answer your question, maybe you could borrow one. You could try to print out a star chart from the internet.

Happy investigating.
Appreciate the comprehensive answer Hemi; very interesting about the other stars mentioned as well as what you and Bluester said about that it could not rise if it was in that start position. I will just have to keep looking and keep making a note of times and positions etc. I have only really observed it about four times (not all in a row) so I suppose in this type of scientific field, that's not enough to make definite conclusions. So it is possible it could even be a planet. Tonight was a almost a full moon so too much light to view it as before.

Yes I only see the night sky in that time range.

To my amateur eyes, it is so distinctive in its shape and colours and brightness that I am pretty sure if I had an astronomer from Perth standing next to me and I pointed it out, he (or she) would say, "oh, that's such & such!"

Just seeing the bright points of red and green coming from it occasionally is quite amazing.

I will keep watching and noting!

Thanks.

Last edited by Dart77; 04-07-2020 at 12:53 AM. Reason: add
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Old 09-07-2020, 11:30 AM
Dart77
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Hi again, I won't write anymore posts until I can contact Perth Observatory as I'm sure someone there would know which one I'm referring to, as it may be most easily seen from my direction and locale. I saw it again last night, exactly the same position, still quite large and a squashed sort of shape but this time the light was more yellow and orange and amazing bright green more predominant as well as bright red points and occasional blue. I can only imagine the beauty of it through a telescope
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Old 09-07-2020, 04:50 PM
astro744
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You mention in your OP that you have Stellarium. Please check location set in the program matches your locale.

I just set mine to Perth and 8:30pm on 2 July, 2020. At SSW I can see Canopus at 20 deg altitude. On 9 July, 2020 at he same time it is about 16 deg altitude slightly further S. Canopus can only get as far as SW (no further west) and this at 40 deg altitude. (Time this occurs depends on date).

There is no way Canopus can be W at 1am (or any other time) so you are likely seeing another star. At 1am there is Spica at 46 deg altitude in the W and Arcturus at 19 deg in the NW. These positions on 2 July, now slightly lower on 9 July.

I believe you witnessed Canopus in the evening and Arcturus in the very early morning, (Arcturus will set closer to WNW around 2am tomorrow morning, 30min later a week ago)

The colour shifting you describe is classics atmospheric refraction and dispersion. When you look toward the horizon you are looking through the edge and thickest part of the atmosphere. Any starlight seen through this layer of air will bend in all directions and different colours will bend different amounts. Light will be stretched horizontally similar to an elliptical setting Sun although it is not a point source. Depending on the thickness of the air and the altitude of the star will determine the amount of refraction and twinkling and dispersion of colour.

May I suggest you get yourself a Planisphere and then you will be able to see what is up and where all year round.

See https://www.bintel.com.au/?post_type...v=322b26af01d5

Make sure you get one for the southern hemisphere at approx your latitude (most sold for 35 South). If you buy from OS direct you may end up with a northern hemisphere version which will be useless.
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Old 09-07-2020, 07:51 PM
Dart77
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Originally Posted by astro744 View Post
You mention in your OP that you have Stellarium. Please check location set in the program matches your locale... I just set [... ] northern hemisphere version which will be useless.
Thanks very much for that great reply astro, and I will read it a few more times after this. That certainly is an extraordinary effect caused by the atmosphere then. If you say that Canopus is not that far west at that time then yes it probably is another star. I know pretty well where the sun sets so I was using that as a guide. Amazing that they seem so similar in appearance. However the one in the middle of the night was quite high (amateur layman's guess at around 40 to 45 degrees) so Spica would fit that. I will look again tonight, if not too cold outside at that time and look at the Planisphere you mention as well. Thanks.

Also out of interest, I sent in a reworded version of the OP to Perth Observatory and this is the disappointing, hurriedly written reply I got:

"Hi Steven

Thanks for your email, from you description it definitely sounds like the light is of terrestrial in nature so I’d be guessing in regards from your location and the direction it’s in, it might have something to do with the Airport

(name) Tour Administrator"


So it seems that it could also be a weather balloon that looks like a star....mmm. (mildly sarcastic comment from someone who has been interested in UFOs since he was 13)

As I mentioned in the OP, a casual look for a couple of seconds might lead a person to think it was a large far-away aircraft approaching the airport. But I thought I made it fairly clear in the email to them that I had observed it for long periods and on many nights.

Last edited by Dart77; 09-07-2020 at 07:52 PM. Reason: typo
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Old 10-07-2020, 01:15 AM
astro744
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No worries, hope you solve your mystery. The cardboard or plastic Planisphere wheel and a red torch are are great tool every budding astronomer should keep in their kit. The iPad version is the electronic equivalent.

I use Stellarium on an iPad rather than PC but I also use Sky Safari. I really like the way Stellarium handles time on the iPad as it allows you to simply drag forward or backward in time with your thumb. When you let go time reverts to 1x speed. On the PC version you need to click on the fast forward or backward arrows multiple times to change the rate from 1x to 10x, 100x etc. (At least my old PC version still has that unless they’ve changed it).

In Stellarium try this.

Look south and place E at the left just off screen and W at the right just off screen and get a slightly curved horizon view. You can bring E and W into view but you’ll have to zoom out which will curve the horizon more. Nothing wrong with that and it will resemble a real Planisphere when curved anyway. The curve is the result of trying to flatten a sphere.

What you want to do is turn on the Celestial (RA/Dec) grid (bluish/green colour) and centre the celestial South Pole toward the top of screen (say 3/4 way up). Now turn on time shift forward to see how the sky rotates as the Earth is turning. If the Sun comes up the stars will vanish but to get them back turn off the atmosphere (cloud button). I think Stellarium has the best twilight colours of any similar type program, very realistic!

If you find Canopus you can see it follows a circle around the South Celestial Pole (SCP) and is almost circumpolar, I.e. never sets from your latitude. (almost but not quite which means it will set for a few hours, 22:30 till 4 presently, changes with date)

Now if you also turn on the Azimuth grid (red colour) and perform the same time shift with Canopus you can see it just gets past 225 deg Az at about 45 deg altitude and then starts moving south again as it sets.

Now put the N horizon in the middle and at 20:30 you can see Arcturus about 35 deg high slightly east of N. It will be on the meridian, (culminate and due north) at 21:20 at just under 39 deg altitude after which it will begin to set which it will do a few hours later in the WNW. Note daily time shift is approx 4 min which is approx 30 minutes per week, 1 hour per fortnight, 2 hours per month or 24 hours per year. In other words Arcturus is at due north at 21:20 on 9 July 2020 and at exactly the same position at 19:20 in one months time but the Sun would have just set and you’ll have to wait for the sky to get darker before you see it by which time it will be further NW.

Enjoy!
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