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Star hovers on horizon and dissapears each night

  • 24-08-2020 12:58am
    #1
    Registered Users Posts: 6,561 ✭✭✭


    Bit of a random one.

    I have often noticed a very bright very 'twinkley' star on the horizon. I am based at the base of the ox mountains so as I look up the hill this star is often sitting just on the horizon, on a clear night I can make out the horizon against the night sky.

    It's not their every night and I have in the past assumed it was a planet as it's one of the brightest things I can see in the sky.

    Last week I was looking at this star and it dissapeared, the sky was very clear and I watched for a while wondering could a band of cloud have moved across it. The next few night I noticed the exact same thing, the star is on the horizon and then ita gone.

    No sight of the star for a few days and tonight it's there again, I watch for a while and it dissapears.

    I'm assuming the star/planet is just moving beyond the horizon but for example the plough is just to the right and higher in the sky and it's there every single night while this star will just show up.

    Tonight it wasn't anywhere to be seen until approx 30mins ago when I was putting the dog in, then it dissapears.


Comments

  • Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    If it is t the left of The Plough it is most likely Arcturus in the Constellation Bootes, which is a star not a planet. A time and direction would be helpful in determining what you see. Arcturus is a good bit away from the horizon at this time of year but is moving closer towards the horizon as the earth tilts on it axis, in October it will set at around 9pm.


  • Registered Users Posts: 6,561 ✭✭✭JJayoo


    If it is t the left of The Plough it is most likely Arcturus in the Constellation Bootes, which is a star not a planet. A time and direction would be helpful in determining what you see. Arcturus is a good bit away from the horizon at this time of year but is moving closer towards the horizon as the earth tilts on it axis, in October it will set at around 9pm.

    On a clear night would you expect to see this star in the same location every night?

    It is left and down from the plough, I am going to download an app that identifies the stars and see what it says.

    The fact that it suddenly dissapears is the bit I found weird.


  • Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    JJayoo wrote: »
    On a clear night would you expect to see this star in the same location every night?

    It is left and down from the plough, I am going to download an app that identifies the stars and see what it says.

    The fact that it suddenly dissapears is the bit I found weird.

    Stars are never in the same position every night, the time changes. Earths orbit in relation to the night sky is roughly 4 minutes shorter than 24 hours (23 hrs 56 mins 4.091 secs to be exact). So any star will be in a different position than that of the previous night.

    If it is close to the horizon when it disappears this is normal, Our own star the Sun does this at sunset. Sounds like it is disappearing behind something in the foreground though as you said there's a big mountain just were you look at it.


  • Registered Users Posts: 6,561 ✭✭✭JJayoo


    Stars are never in the same position every night, the time changes. Earths orbit in relation to the night sky is roughly 4 minutes shorter than 24 hours (23 hrs 56 mins 4.091 secs to be exact). So any star will be in a different position than that of the previous night.

    If it is close to the horizon when it disappears this is normal, Our own star the Sun does this at sunset. Sounds like it is disappearing behind something in the foreground though as you said there's a big mountain just were you look at it.

    When I say dissapear I don't mean it's a gradual thing, I have been watching the star and like flicking a switch it's gone.

    In regards to the position of the stars, the plough has been in pretty much the same location every night for the past two weeks, since I started noting it, but this star is either on the horizon or not visible.

    I thought perhaps it could be mars?

    Anyhow I am downloading a star tracking app and I will be able to point phone in direction and hopefully it will tell me what I'm looking at, I will report back.


  • Registered Users Posts: 14,324 ✭✭✭✭M.T. Cranium


    Not sounding like Arcturus which is fairly high up in the west until quite late into the night (it is the brightest star in that quadrant of the sky). When you say it's left of the Plough and lower down, where is it exactly in relation to the handle of the plough? For example, is it below the first star in the handle, one of the others in the handle, or would you orient it more by the plough's box (the big dipper in other words). To see Arcturus, all you need to do is look due west and up about the same altitude as the handle of the Plough, with some fainter stars it forms an arrow pointing west.

    Can you also confirm it is near your northwest horizon? If by any chance it's near your southwest horizon instead, it could be Antares. I've seen that sparkling in different shades recently (it's a red star). With hills it could be near a horizon, I've got flat country to my southwest so I can see it setting until past midnight.

    Not Mars as that is rising in the east around 10:30 p.m. these nights and getting more prominent all the time.


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  • Registered Users Posts: 1,649 ✭✭✭greedygoblin


    I fired up Stellarium & set the time to around that of your OP. Rewound it & all I could see of note was the ISS passing through the plough from above left to lower right. This was about midnight, so about an hour before you posted OP. Could that have been it?


  • Registered Users Posts: 6,561 ✭✭✭JJayoo


    Thanks for all the replies.

    Well apparently I can't get any of the star tracker apps as my phone doesn't have a compass :(

    I have taken a picture and marked in the approximate positions of the star I am looking at, red dot, and the plough.

    The position of the red dot is west-north-west.

    It is very bright and 'twinkley'. At approx 1am I have seen it dissapear from view 4 times during the last week.

    On a clear night you can clearly make out the silhouette of the horizon/trees against the night sky.

    This star is either on horizon or nowhere to be seen.


  • Registered Users Posts: 6,561 ✭✭✭JJayoo


    JJayoo wrote: »
    Thanks for all the replies.

    Well apparently I can't get any of the star tracker apps as my phone doesn't have a compass :(

    I have taken a picture and marked in the approximate positions of the star I am looking at, red dot, and the plough.

    The position of the red dot is west-north-west.

    It is very bright and 'twinkley'. At approx 1am I have seen it dissapear from view 4 times during the last week.

    On a clear night you can clearly make out the silhouette of the horizon/trees against the night sky.

    This star is either on horizon or nowhere to be seen.

    .


  • Registered Users Posts: 1,649 ✭✭✭greedygoblin


    JJayoo wrote: »
    .

    That is most likely Arcturus as Waffles said earlier. 4th brightest star in the sky.


  • Registered Users Posts: 14,324 ✭✭✭✭M.T. Cranium


    I would agree now that you have added that time and location info.

    Have a look to your west about 10-11 p.m. any clear night and you'll see Arcturus reasonably high up.


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  • Registered Users Posts: 6,561 ✭✭✭JJayoo


    Weird star, watching it again, very 'twinkley' on horizon, dissapears before my very eyes god damn it.


  • Registered Users Posts: 9,203 ✭✭✭tanko


    What is the bright twinkling yellow colored object low down in the eastern sky at the moment?


  • Registered Users Posts: 22,002 ✭✭✭✭Esel


    Two planets are visible there. Jupiter on the right is brighter than Saturn to its left.

    Not your ornery onager



  • Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    Juptier and Saturn would be South and setting SW. Probably Mars but it would have been higher up at the time. Mars would be rising in the East at around 9.


  • Registered Users Posts: 21 raf2020


    Hey, not sure it was mentioned already, but you can install app like Sky Map on your phone and check it easily.

    Cheers!


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