Astronomy

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swerve
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Astronomy

Postby swerve » Mon Aug 07, 2017 8:34 pm

From a local uk astronomy group.
Meteor Showers
This information is for uk so don't forget to add your hour on.
In August we have one of the best showers of the year and a few minor ones.

Perseids: active betwen July 17th and Aug 24th, peak on the night of 12th/13th, but it is also worth looking on a couple of nights either side of this date. ZHR is given as 50 to 80 per hour but this is in ideal conditions - this year we'll be lucky if we see as many as 25 as the bright gibbous Moon will wash out all but the brightest. On the night of 12th the Moon is 80% lit and rises at 22.49. The good news is that the peak is on a Saturday night/Sunday morning so, for most people, work won't interfere. Although meteor watchers are usually told that the best time for observing is after midnight, in the case of the Perseids it could be rewarding to look earlier, when the radiant is low in the SE, as the shower sometimes includes Earthgrazers - rare, slow moving colourful meteors which streak along just above the horizon, leaving bright persistent trails. This shower occurs when the Earth crosses the orbit of comet 109P/Swift-Tuttle and some of the debris left by the comet burns up in our atmosphere.
You may have seen, on the internet, that this shower is going to be the best since records began and there won't be anything like it for the next 99 years - there will be so many meteors that the sky will light up almost as bright as day. Don't believe a word of it! I've checked and no reputable site makes any mention of it - it appears to be one of these enormous Moon, bright pink Moon type urban myths which surface from time to time.

Minor Showers

Kappa Cygnids: active August 3rd to 25th, peak 18th ZHR 3. Some sources give the peak as 14th, so the best bet is probably to look on both nights. The shower has occasionally shown enhanced activity but this is not predicted for 2017.

Aurigids: August 28th to September 6th, peak on the night of Aug 31st/Sept 1st, ZHR 6. Another shower which sometimes produces a much better show - but probably not this year.

Alpha Capricornids: active to August 17th, ZHR 4 to 5. The peak is sometimes given as July 30th but activity is often said to show a plateau, rather than a sharp peak, so try looking during the first few days in August. They are slow moving yellow coloured meteors often leaving trails. There could also be some fireballs.

There are also 3 showers which are often considered to be part of the Summer Antihelion Source, as they have radiants close together on the ecliptic. They are all faint and medium paced, making it difficult to distinguish them from background ANT meteors. As the ecliptic is very low at this time, these are all better seen from further south.

Southern Delta Aquarids: peak 6th, ZHR 1 to 2
Northern Delta Aquarids: peak 13th, ZHR 1 to 2
Northern Iota Aquarids: peak 25th, ZHR 1 to 5

Comets

We have one faint comet, not visible to the naked eye , magnitude somwhere between 10 & 12 (as always, sources give different info). 2015 ER61 PanSTARRS is now reaching an altitude of 30 degrees while the sky is still reasonably dark. It moves from Aries into Taurus on 2nd, rising at around 23.30. During the third week of the month it passes about half a degree below the Pleiades.


Eclipses

On August 7th, there is a partial lunar eclipse, however from the UK we will only see the penumbra - the faint outer part of the Earth's shadow - on the face of the Moon and probably won't notice any appreciable dimming. When the Moon rises at 20.44 a large part of it will already be in shadow, the maximum being only a few minutes later. The Moon moves out of the shadow at 21.50.

On 21st for those who live in, or are visiting certain areas of the USA (or the Atlantic or Pacific Oceans) there is a total solar eclipse. Here, weather and low Western horizon permitting, we might see a partial eclipse. However, only a very small part of the Sun (6% at maximum) will be covered by the Moon. The eclipse starts at 19.39 when the Sun is only 6 dgrees above the Western horizon, the maximum is at 20.02 when its altitude has dropped to 2.75 degrees, the Sun sets at 20.23.

REMEMBER: NEVER look directly at the Sun without proper eye protection. SUNGLASSES ARE NOT ENOUGH, your eyes will still be permanently damaged.
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gerryh
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Re: Astronomy

Postby gerryh » Mon Aug 07, 2017 9:01 pm

Thanks for the info. very interesting.
Just watched the full, well 99.87%, moon rise here near Cajiz, Costa del Sol. Didn't notice any partial eclipse.
Will look for the Perseids around the 12/13th.
Cheers
Gerry
Last edited by gerryh on Tue Aug 08, 2017 7:13 am, edited 1 time in total.
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peteroldracer
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Re: Astronomy

Postby peteroldracer » Mon Aug 07, 2017 10:51 pm

How come Russell Grant did not give this much info? :-)
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Wicksey
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Re: Astronomy

Postby Wicksey » Tue Aug 08, 2017 10:11 am

gerryh wrote:Thanks for the info. very interesting.
Just watched the full, well 99.87%, moon rise here near Cajiz, Costa del Sol. Didn't notice any partial eclipse.
Will look for the Perseids around the 12/13th.
Cheers
Gerry


No I didn't either. I saw it mentioned on the Spanish weather programme but the times were around 21:20 and the moon didn't rise above the hill beside us until about 21:45.

I have lost count of the number of times I have sat out trying to avoid being bitten waiting to the see meteor shower and been very disappointed. I have seen the occasional single large shooting star but nothing like the so-many-an-hour that are promised. Last year I think it was a cloudy night.

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Re: Astronomy

Postby olive » Sat Aug 12, 2017 11:29 pm

Wicksey. I am with you. Previous years not seen a thing.

Tonight we took a visitor to the spot we use each year. It has very little light pollution . Saw over twenty in half an hour. What surprised me was how fast they were. It was hard to orientate where they were coming from but our guess was from the North.

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Wicksey
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Re: Astronomy

Postby Wicksey » Sun Aug 13, 2017 10:10 am

Last night was cloudy here so I didn't have to torture myself by sitting out and being disappointed :) You were lucky olive :thumbup:

However, on Friday night I was out about 11pm admiring the stars as the moon hadn't risen and it was lovely and dark. Then 'pow' .... the most amazing shooting star whizzed by .... I almost fell over with the excitement of it. It was huge and had a 'tail'. I will be happy with that if I don't see any more. I find the ones I have seen tend to come from the north/north-east direction.

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chrissiehope
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Re: Astronomy

Postby chrissiehope » Sun Aug 13, 2017 10:51 pm

We were in N Wales last night, & the sky was pretty clear - we saw about half a dozen - dead chuffed :-)
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