CLICK HERE TO DOWNLOAD A "PRINTER FRIENDLY" PDF FILE VERSION (52KB)

Knowle Astronomical Society Almanac 2007

Knowle Astronomical Society is pleased to present its annual review of significant astronomical events for the year ahead. We hope that beginners and experts alike will find it informative and useful. Every effort has been made to ensure accurate timings for these events from the vicinity of Knowle and Dorridge. It is recommended however that observers check exact local timings a few days beforehand (as well as the weather forecast!). This year’s edition also includes new appendices giving details of the Messier objects and some notable double stars. Please note that when observing before sunset or after sunrise every precaution should be taken to avoid looking directly at the Sun using any form of optical instrument, including cameras and even the unaided human eye.

British Summer Time

All times in this almanac are quoted in Greenwich Mean Time (GMT). British Summer Time (BST) will be in force between March 25th and October 28th. To convert from GMT to BST add one hour to the quoted times.

Sun and Moon

Equinoxes and Solstices

Eclipses

A Total Lunar Eclipse takes place on March 3rd between 21:31 and 1:12 the following morning. This is the only eclipse visible from the British Isles during 2007.

On March 19th a Partial Solar Eclipse is visible from much of Asia and Alaska.

A Total Lunar Eclipse on August 28th is visible from most of the Americas, the Pacific and eastern parts of Asia.

On September 11th a Partial Solar Eclipse will be visible from parts of South America and Antarctica.

The Planets

The best opportunities to see Mercury in 2006 occur in the evening sky for a couple of weeks around greatest elongation east on February 7th and in the morning sky for a couple of weeks around greatest elongation west on November 8th. It may also be possible to find Mercury with binoculars close to a very young waxing crescent Moon low down on the horizon just after sunset on May 17th.
Having returned to the evening sky at the end of 2006 Venus will be a brilliant and conspicuous object for several hours after sunset during the first half of 2007. Reaching Greatest Elongation East on June 9th it is then gradually lost into twilight over the next couple of months until emerging into the morning sky during August. It will then proceed to put on an equally impressive pre-dawn display during the final months of the year.

Mars is too close to the Sun to be properly observed during the first few months of 2007. From May onwards however it steadily gains altitude in the morning sky and by August it will be rising before midnight. Mars reaches opposition in Gemini on December 24th. This is quite a distant opposition and the angular size of the planet is only 16” compared with 25” for the very close 2003 opposition.

Jupiter starts the year as a morning planet but by the end of April is rising before midnight and reaches opposition in Ophiuchus on June 5th. It then remains an evening object until lost in twilight during November. This year’s apparition is not particularly favourable from our latitude as the planet is never more than 16O above the horizon. The occultations, transits and shadow transits of Jupiter’s Galilean satellites are easy to observe in small telescopes. It is very common to see one or even two transits or shadow transits in progress, but triple and other multiple events are much rarer. This is especially the case at the moment because (owing to the current orientation of the orbital plane of the satellites relative to Earth) Callisto, the outermost of the four, is not participating in any of these events again until 2008. The only multiple events observable from the British Isles during 2007 are:-

Both of these events (particularly the latter) will be tough to observe owing to the low altitude of the planet.

Saturn is a conspicuous evening object at the start of 2007 and reaches opposition on February 10th in Leo. The northern polar regions of the planet are now no longer obscured by the planet’s rings which will continue to close until we see them edge on during 2009. Saturn remains an evening planet until lost in twilight during July. It then emerges into the morning sky during September and will rise before midnight again by the end of November.

Uranus which, at magnitude 5.7, is only just visible to the naked eye under good conditions is at opposition in Aquarius on September 9th and Neptune which, at magnitude 7.8, requires at least good binoculars to see, is at opposition in Capricornus on August 13th.

Conjunctions and Occultations

The Moon encounters each planet during its monthly journey through the Zodiac. These conjunctions are often attractive sights, particularly those that occur at dawn or dusk when the Moon displays its crescent phase. Conjunctions between the planets are also reasonably frequent events. Sometimes the Moon will even pass directly in front of (i.e. occult) a planet or first magnitude star. Lunar occultations of fainter naked eye stars are fairly regular events. The following is a synopsis of the most notable conjunctions and occultations during 2007.

Venus has a series of encounters with the waxing crescent Moon in the evening sky during the first half of the year, the closest of which are the January 20th and February 19th events when the separation is less than 1½°. Of these two, the February conjunction will be easier to observe since the Moon will be two days old compared with just one day old for the January event. By June Venus is joined by Saturn in evening twilight and on the 18th and 19th of June the two planets are close to a thick (3 – 4 day old) crescent Moon. Venus is actually occulted by the Moon during daylight on June 18th. This event takes place between 14:01 and 15:21 and should be observable with binoculars. After this date the separation between Venus and Saturn continues to close until they are less than a degree apart on the evening of July 1st. The two remain close together as they move into the morning sky and there is another attractive conjunction on the morning of October 7th when the waning crescent Moon will be between them.
Mars has a very close conjunction with the Full Moon, as it comes to opposition on the night of 23rd and 24th December. By 03:53 on the 24th the separation is only 2’.

Saturn also has a series of very close encounters with the Moon during 2007. The two are less than 2°apart as they rise on January 6th and then pass within just 11’ of each other on February 2nd when the Moon will be full. A month later on the evening of March 1st they are close again and between 2.44 and 2.50 the following morning there will actually be a ‘grazing’ occultation. During this very interesting event the planet will be only partly obscured for a few minutes by the Moon’s limb. The next encounter is closer still and at just after 5am on the morning of March 29th we will be able to see the start of a full occultation, low in the western sky before the Moon sets. On the following morning (between 03:30 and 4:19 on March 30th) there is an occultation of Regulus, the brightest star of Leo. Regulus is again occulted on July 17th but this time the event will be in broad daylight with the crescent Moon at fairly low altitude and difficult to observe. April’s encounter between the Moon and Saturn will not be particularly close as observed from the British Isles, but on 22nd May we will be able to see a complete occultation between 19:10 and 20:17. This event will start in daylight and Saturn will re-emerge from behind the Moon just after sunset. It should however be readily observable in telescopes or even binoculars.

Uranus is occulted on the evening of 18th February but this event will be at low altitude and therefore difficult to observe.

The Moon had several skirmishes with the Pleiades in 2006 and there are more to come in 2007. Maia (magnitude 3.9), Taygeta (4.3) and Caelano (5.4) are occulted on the evening of February 23rd. These three plus Electra (magnitude 3.7) are occulted in the very early hours of August 7th. The same thing happens again on the night of October 27th. The final event, on the evening of December 21st is a repeat of the first, with the Moon missing Electra but occulting the other three.

Minor Planets

Many dozens of minor planets (asteroids) are within range of amateur instruments. Amongst the first ten to be discovered the following come to opposition during 2007:-

Meteor Showers

The following table shows the most important annual meteor showers with the dates of their expected duration during 2007, the date of maximum intensity, estimated zenithal hourly rate (ZHR) at maximum and the phase of the Moon at maximum. Those showers with the highest percentage for the lunar phase will experience the most interference from moonlight, consequently reducing the numbers of meteors observed.

The Perseids in August are likely to be the best observed shower this year with virtually no interference from the Moon around the time of maximum.

Sources

The following are gratefully acknowledged:-

Burnham’s Celestial Handbook, Castle Point Astronomy Club, Graystel Astronomy Software, HM Nautical Almanac Office, International Meteor Organization, National Maritime Museum / Royal Observatory Greenwich, Washington Visual Double Star Catalog, Whitaker’s Almanack.

Appendices

Appendix 1: Summary of Key Events in 2007
Appendix 2: The Messier Catalogue
Appendix 3: 100 Notable Double & Multiple Stars

Note: appendices 2 & 3 are included with the internet version only. If you would like a hard copy please contact Nigel Foster.

 Appendix 1: Summary of Key Events in 2007

Appendix 2: The Messier Catalogue

Appendix 3: 100 Notable Double & Multiple Stars

Note: for both appendices Right Ascension (R. A.) and Declination co-ordinates are J2000 epoch.