Night Shining Clouds

Emma Rennie July 2019 Lewis

Noctilucent clouds over the Isle of Lewis by Emma Rennie

Longer days and brighter nights mean less time under the stars, especially if (like me) you live in the far north of Scotland, when astronomical twilight vanishes completely from around late May.

One advantage to this, however, is increased opportunities to observe some of the highest cloud formations on Earth, so called Noctilucent clouds – or ‘night shining’ clouds.

These beautiful, wispy and wave like clouds sit around 50 miles overhead in a region of our atmosphere known as the mesosphere.  The clouds themselves are composed of fine ice crystals and atmospheric dust, and can even be seeded from the disintegration of small meteors which burn up around the same altitude – called ‘meteor smoke’.

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Night shining clouds from Edinburgh by Chris Cogan

Specific conditions are required to see these clouds, and the further north you live generally the better (roughly between latitudes 50 – 70 degrees).

The Sun must be below the horizon in such a way that its rays light up the clouds from below.  Broadly speaking this can happen during a period known as nautical and astronomical twilight – when the Sun sits between 6 and 18 degrees below the horizon.  This means noctilucent clouds are normally only visible from mid-May to mid August from the British Isles.

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These clouds are normally only visible when the Sun sits within the nautical and astronomical twilight bands, between 6 to 18 degrees below the horizon.

Best Times to Observe

Times vary depending on your latitude but here are the earliest times for nautical twilight at various locations.  These times therefore represent the earliest you’re likely to be able to observe the clouds, although optimal times will likely be between 30 – 60 minutes after these times:

Shetland (60.5 degrees north) – 11.35pm

Inverness (57.5 degrees north) – 11.05pm

Glasgow (55.8 degrees north) – 10..45pm

Manchester (53.5 degrees north) – 10.15pm

London (51.5 degrees north) – 9.50pm

You might think these times suggest living further south affords you longer opportunities to observe them.  This isn’t true as the further south you live the more likely you are to experience periods of actual darkness later on, when the Sun dips below 18 degrees – too low to illuminate the cloud base.

Good luck and please post some pictures on my Facebook blog if you capture any.

Gav Ross July 2018 Aberdeenshire

Captured by Gav Ross from Aberdeenshire

 

 

 

Comet SWAN Update

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Comet SWAN update! ☄️ Comet SWAN is just starting to become viable for observation at northern European latitudes as it sails through the constellation Perseus. This one will be very tough to see due to its low altitude and lack of darkness 🌅 . In fact it may not be visible at all if you live too far north. However, if you’re up for a real challenge, grab your binoculars and read on.

Just like this week’s Venus and Mercury planetary conjunction 🪐 , SWAN will be visible towards the north 🧭. As the week progresses it will rise higher and higher in the sky so theoretically should become easier and easier to observe (see attached guide images). Unfortunately this will be countered by less and less darkness as May advances.

The absolute best instrument for spotting a comet is a pair of binoculars, or the widest possible eyepiece you have on a telescope. Scan the sky using my pictures and bright stars for reference. Don’t expect a huge streaking object like you’ll see in astronomy magazines (or the front image I’ve attached 😆 ) – If you’re very lucky you might detect a tiny and faint smudge.

The darker your surroundings and more dark adapted your vision the better 🌑 👀 , so stay away from bright street lights and mobile phone screens for at least 15 minutes. If you live under street lights 🌃 your chances of sighting the comet are far lower but don’t let that put you off. Comets can vary in brightness dramatically and can very occasionally brighten enough to be detected naked eye.

What’s great about this challenge is you can also look out for Mercury and Venus at the same time, as all the action takes place towards the same cardinal direction – North.

Good luck and clear skies.

 

Venus and Mercury Conjunction

A rare opportunity to observe a Venus  and Mercury conjunction over the next few days.

From tonight (Monday) Mercury will appear progressively closer to Venus in the NW sky after sunset, leading to conjunction on Thursday and Friday night. An excellent chance to see Mercury in binoculars or observe the phase of both planets in a garden telescope.

Mercury is much dimmer and more challenging to see than Venus so my advice is to use Venus as a reference for finding Mercury in your binoculars or telescope. Those, like myself, living in the north of Scotland might need to wait a little longer after sunset to see the planets (due to pervading daylight).  This makes it more of a challenge as both planets will be closer to the horizon by then.

Moreover, as both planets will only be around 10 degrees above the horizon at conjunction you’ll need to get away from tall trees or buildings that might obscure your view NW. Hopefully those pesky clouds stay away too.

Clear skies and good luck.

Ursa Major Video Guide

 

My video stargazing guide to the constellation Ursa Major, known to stargazers and astronomers in the northern hemisphere by its famous asterism of the Plough or Big Dipper.

Many thanks to Rising Galaxy of Cosmicleaf Records for gifting the background music to this piece. If you like drone ambient or cosmic chill out music please check out their web stores for more of the same.

Clear skies.

Sirius the Glitter-ball

 

A video of Sirius (the brightest star in the night sky) twinkling on the horizon, captured by Steve Brown @sjb_astro. Many people think they’re seeing a low altitude aircraft or UFO when they witness this.

This phenomenon occurs (to a lesser extent) with any bright star low on the horizon due to the vast amount of atmosphere you’re seeing it through. As stars gain elevation, and less atmosphere is between us and them, they shine more steadily, and views are hugely improved.

The difference in the amount of atmosphere you look through with elevation is very striking (as demonstrated in the sketch below).  Particularly for faint deep sky objects like galaxies, high elevations makes a dramatic difference to the quality of visual or photographic images you’ll collect.

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How much atmosphere you look through with observing angle.  At the zenith (overhead) you look through over 2/3 less atmosphere than at the horizon.

Star Stories Astrophotography Special

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Eric presenting his guest talk up at Abriachan

There were only a few stars up at Abriachan Forest tonight for our Star Stories Astrophotography special, but some nice early views of the waxing crescent Moon and Venus before the weather really turned and a mini snowstorm descended.

Many thanks to our guest speaker Eric Walker from the Highlands Astronomical Society for delivering a fantastic talk on astrophotography.  Eric showcased a ton of amazing images he’s taken over the years demonstrating his passion for astronomy and observing.

Clelland also entertained in the round house with storytelling and we had a nice impromptu discussion about the night sky over the campfire between changeovers.

The next Star Stories is our Vernal Equinox special in March, which will be the last opportunity for dark sky observing this season before the return of longer days.

Eventbrite link here

Urban Astronomy Aurora Special

Many thanks to Graham Bradshaw of Graham Bradshaw Photography for tonight’s fascinating guest talk on hunting down and photographing the Aurora. Here’s one of the beautiful time lapses Graham shared with us during his presentation.

 

Graham also provided a lovely selection of his images (see below) along with camera settings to help budding night sky and aurora photographers.

We also took advantage of some clear breaks in the sky after the talk and walked up to the Nature Reserve to view some bright constellations and star clusters.

Thanks to everyone who came along. The next Urban Astronomy event is our Venus special on March 12th. Booking link here.