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Lunar Eclipse 2018

 eclipsed moon

A total eclipse of the Moon will occur on July 27. Weather permitting, this will be the most central lunar eclipse since June 15 2011.

Circumstances

This eclipse will be visible from India, Africa and Europe but not from north America.
However, only the latter part of the eclipse will be visible from the UK as the Moon will rise above the horizon in full eclipse.
This is a fairly central eclipse insofar as it will have a gamma value of 0.11 (where a value nearest 0 is most central, and that values can range between -1 and +1 is the limit of the earths umbral shadow) – typically more central eclipses are a deeper red hue at greatest eclipse.

Here are the Gamma (G) values for previous lunar eclipses:

  • 2011-06-15 G:0.0899
  • 2011-12-10 G:-0.3883
  • 2014-04-15 G:-0.3017
  • 2014-10-08 G:0.3827
  • 2015-04-15 G:0.4460
  • 2015-09-28 G:-0.3296
  • 2018-01-31 G:-0.3014
  • 2018-07-27 G:0.1168

Timings

The all important times for the various stages of the eclipse are provided below (in UT)

  • Enter Penumbral shadow (P1) - 17:14
  • Enter Umbral shadow (U1) - 18:24
  • Fully within Umbral shadow (U2) -19:30
  • Greatest or Mid eclipse - 20:21
  • Exiting Umbral shadow (U3) - 21:13
  • Fully exited Umbral shadow (U4) - 22:19
  • Exited Penumbral shadow (P4) - 23:38

Totality (within part of the Umbral shadow) will last for 3h 54m (1h 43m within complete shadow)
Umbral Magnitude is expected to be 1.6

Moonrise Times (in UT - add +1 for BST)

  • Glasgow - 20:31
  • Dublin - 20:27
  • Leeds - 20:10
  • Cardiff - 20:06
  • Plymouth - 20:06
  • Greenwich - 19:53
  • Selsey - 19:53
  • Dover - 19:46

 

Viewing the Eclipse 

Lunar eclipse circumstances

The majority of the 2nd half of the eclipse shall be visible from all of the UK. However, if you are further north than Carlisle and the Kiedler Forest the moonrise will occur after mid eclipse. The further south and east you are, the more you’ll be able to view.
However, you’ll have to travel to the Continent to view the start of the eclipse as this isn’t visible from anywhere in the UK.

That being said, I’m sure that we shall see a slew of amazing photos – a deep red eclipsed full moon coming over the horizon will surely be quite a sight.

For some inspiration why not check out members observations of previous lunar eclipses (some shown below) in the BAA Gallery and on BAA Member Pages

To learn more about observing the Moon have a read of Bill Leatherbarrow's tutorial on observing the Moon, or this tutorial on the phases of the Moon.

Steve Harvey
Director of the BAA Computing Section

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BAA Articles

Observer's Challenge - Observing Mars

Mars is making its best approach to us for fifteen years. This is in terms of closeness (57.6 million kilometres), brightness (about -2.8 mag) and biggest (24.3” of arc). The planet comes to Opposition on 27th July 2018 and makes its closest approach on 31st July 2018.

Whilst it is the best for fifteen years, for observers at UK Latitudes, it is in very nearly the worst place, being very close to the horizon. This is one of the reasons this is being labelled a challenge. For observers in more southerly latitudes it is not such a challenge in this regard.

Stellarium: July 31st at 23.00 UK latitude

The graphic above is from Stellarium and shows the Southern Horizon at 23.00 hours on the 31st July from UK latitudes. It shows how low in the sky Mars is at this time. The horizon shown does not include any landscape features which will need to be taken into account for your own local conditions.

At around the time of Opposition, Mars is in Capricorn, moving with a retrograde motion. In addition to the challenges mentioned, dust storms are apparent on the planet which may, or may not, be present at the time of opposition. So, there are several challenges within this one challenge.

At the beginning of July, Mars will be at about -2.1 magnitude and about 21 arc seconds diameter. Dust storms aside, the entire surface of Mars should be able to be seen during the month of July. For example, Syrtis Major should be visible by about the night of July 7th.

Members are encouraged to submit Images or drawings of ‘the red planet’ to their areas on the website, at https://www.britastro.org/member_profiles. They are also encouraged to send these to Dr Richard McKim, Mars Section Director at https://britastro.org/section_front/17

This image of Mars was taken by James Dawson. It was taken on 16th April 2014 from Nottingham. A C11 was used with a one shot colour camera. The exposure was 120 seconds at 80fps. James' member area is at https://britastro.org/profile?id=645

Other Images of Mars in Members's areas can be found by using the Search Category button and choosing 'Mars'. The current images of Mars can be found here https://britastro.org/recent-images-by-category/154

As well as images, sketches or drawings of Mars are also very welcome. Shown here is a very nice observation taken by Paul Abel on the 23rd June 2018.

Paul's Member area can be found at https://britastro.org/profile?id=793 

This observation is entitled 'A dusty Mars' so the dust storms are starting to take effect.

Another challenge which has been recommended by Dr Richard McKim is to make observations of the brightness of Mars over the next couple of Months as Mars approaches and then passes Opposition at the end of July.

One way of doing this is to make a judgement on the magnitude of the Planet against some nearby bright stars. There are several bright stars fairly near to Mars at the time of Opposition.

These are listed in the table below.

Richard would be very pleased to receive any such observations. Very few people did any at the time of the last Opposition, thus this would be a useful addition to the scientific record for Mars.

Please send any of these observations to Richard at the link mentioned above.

Hopefully there is something of interest for you to take on for this forthcoming Mars Apparition.

John Chuter

Archivist

 

 

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BAA Observing Sections Comet

Comet 21P approaches the North America Nebula

It will be a challenging observation due to midsummer skies and a First Quarter Moon but the periodic comet 21P/Giacobini-Zinner will be passing the bright emission nebula NGC7000 (the North America Nebula) in Cygnus between June 19 and June 21. The comet is currently around 13th magnitude but will brighten over the summer to become a potentially 6th magnitude object by September. At present the comet is a small fuzzy spot with a short tail to the south west and it will be completely overwhelmed by the large nebula but it will be interesting to compare the two objects. A chart showing the encounter is here. Please send any observations to the Comet Section.

The image at left shows the comet on the morning of 2018 June 13. The field of view is around 11 arcmin square. More images of this comet are available in the Section's archive here.

Update on 2018-06-18 - Here is an image of the comet approaching the nebula taken from New Mexico.

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BAA Tutorials Starting out

Noctilucent Clouds – a beginners guide

Noctilucent clouds (popularly referred to by the abbreviation “NLC”) are high atmosphere clouds which occur over summertime at mid latitude locations. They form at very high altitudes – around 82 km above sea level – and are, thus, a quite separate phenomena from normal weather or tropospheric cloud. They appear as thin streaks of “cloud”, often a pearly-blue colour, reminiscent of “mares-tail” cirrus cloud formations.

NLCs can be seen from around mid May to early August during the darkest part of a summer’s night when the Sun is between 6 – 16 degrees below the horizon. Typically, they will occupy the northern horizon, along the twilight arch, extending to an altitude of 10 – 15 degrees. Over the NLC “season” the bright star Capella dominates this part of the sky and serves as a good marker for the NLC observer. They used to be associated with northern UK but have been seen as far south as central France and they seem to be spreading further south with each season.

Observations of NLC remain of great value to professional scientists studying upper-atmosphere phenomena. Useful observations are very easy to make and require no special equipment.

The following information lists the important details you should include in your report:

LOCATION: Give the latitude and longitude of the place observations were made. Alternatively, give the name of the nearest town or city.
DATE: Use the “double-date” convention as used in reporting aurorae. That is, “June 21-22″ would refer to the night of the 21st and the early hours of the 22nd.
TIME: Try to use universal time (UT) even though British Summer Time (BST) will be in civil use for UK observers. Remember, UT = GMT = (BST – 1 hour).

Observations
The following features and details should be recorded at 15 minute intervals (i.e. on the hour, quarter past, half past and so on):

AZIMUTHS If you see NLC measure the left (western) and right hand (eastern) extent of the display. This is measured in degrees with west = 270, north = 000, east = 90 and south = 180. Polaris defines the northern point of your horizon. Azimuths can be gauged by using a clenched fist, held at arms length, as a measure of 10 degrees.
ELEVATION If possible, measure the angle subtended by the uppermost part of the display. A simple alidade can be made from a protractor and plumb line for this purpose.
BRIGHTNESS NLC brightness is measured on a three point scale with 1 = faint; 2 = moderate; 3 = very bright.

Structure
NLC forms are classified into 5 easily identified structures. Any combination of the following is possible:

Type 1: Veil – A simple structureless sheet, sometimes as background to other forms.
Type 2: Bands – Lines or streaks, parallel or crossing at small angles.
Type 3: Waves – Fine herring-bone structure like the sand ripples on a beach at low tide. Very characteristic of NLC.
Type 4: Whirls – Large-scale looped or twisted structures.
Type 5: Amorphous – Isolated patches of NLC with no definite structure.

Drawings
Simple sketches of the NLC can be very useful. These are best made in negative form with the darker parts of the sketch corresponding to the brighter NLC.

Photography
Photographs of NLC can easily be taken with a digital camera firmly fixed to a tripod; using 400 ISO gives good results. An exposure of 3-6 seconds with a lens aperture setting of f3.4 will normally suffice. However, it is always best to take several shots of different exposures, and pick the best exposure. Once this is done you can try a panorama by taking several overlapping photos. Make sure the camera is level, then move it about 20 degrees after each shot, starting just beyond one end. This makes sure that you will get it all, because the camera will see more than you can.

Sandra Brantingham

Sandra is the Director of the Aurora and Noctilucent Cloud Section of the BAA.

A selection of observatorions of noctilucent clouds which BAA members have uploaded to their Member pages can be found here.

[Thumbnail image by Gordon Mackie]

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BAA Articles

Observer's Challenge - Observing Saturn

Saturn reveals its loveliness even in a small telescope and observers will always remember their first view of the planet and its ring system.

Saturn is always a fine sight for any observer but this year it is located at -25 latitude and -26 from the first of July. Opposition is 2018 June 27. Being at such a low altitude in Sagittarius makes observing any fine detail very difficult in the UK. The rings are around 25° but it will be a challenge to see Encke’s Division. This division is situated in Ring A which is the outer ring beyond Cassini’s Division. Cassini’s can be seen with a 3-inch refractor under favourable conditions but Encke’s is much more elusive.

The satellites will be a challenge too and light pollution and low altitude will make Iapetus, Rhea, Tethys and Dione difficult. The BAA Handbook gives position data for these satellites on pages 83 and 84; Iapetus is brighter at Western Elongation and is much further out but mid-June and later August will be the best time to look for it.

There are two challengers therefore, these being to see if you can see Encke’s Division and also any satellite fainter than Titan. If you do not manage to meet either challenges, Saturn will always be a magnificent sight anyway.

As well as observing, why not make a sketch of Saturn and its rings and any visible moons; here is a sketch by Paul G. Abel made 2018 May 08 from the University of Leicester's Observatory. Or maybe you prefer to take images. Please do submit any sketches, images or observing notes to Mike Foulkes at the BAA's Saturn, Uranus and Neptune Section and upload them to your member page.

For more information on Saturn read this article by Mike Foulkes, or check out the BAA Handbook.

Alan Heath
Long Eaton, Nottinghamshire


Alan is a former BAA Saturn Section Director, 1964-1994, and continues to submit regular observations to the BAA. Alan is pictured here giving a talk to Nottingham Astronomical Society on the use of filters for planetary observation, 17th August 2017; Alan's article, The 'Great Filter Debate', which was published in the Journal in 2017 can be found here.

[Thumbnail image: Saturn, June 18th 2017, John Sussenbach, NL]

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BAA Gallery Picture of the Week
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Solar Filaments and Chromosphere

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About this observation
Observer
Mick Nicholls
Time of observation
24/06/2018 - 10:05
Object
Sun
Observing location
Sheffield, UK
Equipment
80mm Refractor
DMK 31 camera
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This is a 2 pane mosaic, taken with an 80mm Starwave ED-R refractor, a DMK31 camera and a Daystar QUARK chromosphere version all on an HEQ5 Pro Synscan gotot mount. Image taken from Sheffield UK.  Image settings are gain 260, gamma 30,  30fps and 66th of a second exposure. Image stacked in Autostakert 3 and Registax 6 finished off in Photoshop CS4.
Copyright of all images and other observations submitted to the BAA remains with the owner of the work. Reproduction of the work by third-parties is expressly forbidden without the consent of the copyright holder. For more information, please contact the webmaster.

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