During June the full moon is on the 3rd, Venus remains a brilliant object and transits the sun
on the 8th - a rare event, Uranus is stationary on the 11th, Mercury is at superior conjunction on the 18th and the summer
solstice is on the 21st.
||By the 30th June, Mercury will set about an hour and a half after the sun. At -1.1 magnitude
it will be visible low in the northwest. The planet is at superior conjunction on the 18th.
The best times to observe Mercury are when it is an evening star in the spring and a morning star in the autumn. In midsummer the lighter skies make visibility difficult near the horizon.
||2004 is an exceptional year for observing Venus and during June the planet is a brilliant -4.5
magnitude in Taurus. For the first few days of the month Venus is an evening star visible in the northwest.
On the 8th June, Venus will be at inferior conjunction
and will transit the sun. Transits of Venus are rare, taking place at greater
than 100 year intervals and usually in pairs. The last two transits of Venus were in 1874 and 1882. This month's transit
will begin at 7.20h and lasts 6 hours until 13.20h, the total event visible from Europe as a small black disc crossing
the lower part of the sun from left to right. THE SAME PRECAUTIONS AS FOR OBSERVING SOLAR ECLIPSES SHOULD BE HEEDED, TO PROTECT THE EYES! The next transit will
be in late June 2012. After that, transits of Venus won't occur again until 2117 and 2125.
By mid-June the planet will reappear as a morning star in the northeast
sky where it will remain as a brilliant object throughout the remainder of 2004.
Before and after inferior conjuction, when Venus is
the closest it comes to the earth, are the times at which the planet is most brilliant and can be seen setting or rising
4 hours after or before the sun. The dates of the next two inferior conjunctions are October 28th 2010 and October 26th 2018.
||Mars has faded from its brilliant August 2003 display to 1.8 magnitude by the end of June
when it sets less than 2 hours after the sun. The planet is in Cancer with the moon nearby on the 19th and 20th. Mars will be an evening object until
At opposition on the 28th August last year, Mars was only 56 million kilometres from the earth. It showed a
disc of 25.1 seconds of arc across which is almost as large as it can ever appear. Mars started 2003 at 310 million kilometres from
the earth at 4.5 seconds of arc and 1.6 magnitude. By opposition it brightened 50 times to reach -2.9 magnitude but faded to 0
magnitude by December. Even to the naked eye Mars was a striking object in the summer and autumn sky, easily identifiable by its
reddish hue in an area of sky poor in bright stars. Mars will not be as close again for another 15 years.
These favourable oppositions occur every 15 years but other oppositions occur at average intervals of 2 years 2 months. In general Mars is observable every other year, being too close to the sun for favourable conditions during other times. Brightness at opposition varies from -1.0 to -2.9 magnitude, and when furthest from the earth it fades to 1.7 magnitude. The planet can be identified by its orange-red colour.
||Jupiter is at -1.9 magnitude in Leo setting by 1.30h by the end of June. The moon is closeby
on the 23rd.
Being 770 million kilometres from the sun, the difference in brightness between opposition and conjunction varies less than with Mars, from about -2.8 to -1.8 magnitude.
The 4 largest moons of Jupiter are easily visible through a small telescope, ranging from 4.6 to 5.6 in magnitude. The innermost, Io, takes 1.8 days to orbit the planet making its motion easily detectable within a few minutes.
||Saturn is at 0.1 magnitude this month and in Gemini throughout 2004. Setting less than
an hour after the sun by the end of June, the moon is nearby on the 18th and 19th.
Saturn crossed the equator into the northern hemisphere in 1996 where it will remain until 2010 with the southern side of the ring system facing the earth. Because of its distance, its brightness varies little between opposition and conjunction but is affected by the huge ring system. Seen edge on the rings contribute little or no light.
Every 15 years the plane of Saturn's rings passes through the sun, illuminating first the north and then the south side. For a few days the rings are edge on to the sun. About the same time the earth passes through the ring plane and, depending on the earth's position this may happen just once or 3 times. During 1995/96 there was a triple crossing and the next will be 2038/39. The next single crossings will be in 2009 and 2025.
Saturn's largest moon, Titan, is visible in small telescopes orbiting outside of the ring system.
||Uranus is in Aquarius throughout 2004 rising about 1.00h in mid-June. The planet is
stationary on the 11th, at 5.9 magnitude with the moon nearby on the 8th.
Brightness varies slightly reaching 5.6 magnitude at opposition. This is bright enough to see with the naked eye but identifying it against the stars is difficult.
||Neptune is in Capricorn throughout 2004. At 8.0 magnitude, it rises about 24.00h by the end
of June with the moon nearby on the 7th.
Neptune has an average magnitude of 7.9 which varies little with changing distance.
||Never brighter than 13 magnitude, Pluto is only visible through powerful telescopes and we will therefore not be reporting on its position in the sky.|
Other Objects & Events
||Full moon: 3rd at 6.00h
Last quarter: 9th at 22.00h
New moon: 17th at 22.00h
First quarter: 25th at 21.00h
||Eclipses during 2004:
19th April - Partial eclipse of the sun.
This partial eclipse will be visible from a part of Antarctica, the south east Atlantic,
south west Indian Ocean and southern Africa.
4th May - Total eclipse of the moon.
Visible from Antarctica, Astralia, most of Asia, Europe and eastern south America. The eclipse begins at 17.50h,
the moon enters the umbra at 18.48h and totality starts at 19.52h with mid-eclipse at 20.30h. Totality ends at 21.08h, the moon leaves
the umbra at 22.12h and the eclipse ends at 23.09h.
14th October - Partial eclipse of the sun.
Visible from north east Asia, Japan, western Alaska and the western Pacific Ocean.
28th October - Total eclipse of the moon.
Visible from the Arctic, western Russia, parts of the Middle East, Africa, Europe, Greenland, the Americas and the eastern
Pacific Ocean. The eclipse begins at 00.05h, the moon enters the umbra at 01.14h, totality starts at 02.23h and mid-eclipse is at
03.04h. Totality ends at 03.44h, the moon leaves the umbra at 04.54h and the eclipse ends at 06.03h.
||Meteor Showers in 2004:
Favourable conditions for viewing meteors are between last and first quarter moon during the new moon, as moonlight seriously interferes with the number of faint meteors that can be seen.
2nd-4th January - The Quadrantids.
The average hourly rate is about 10. Conditions are unfavourable with a full moon on the 7th. The radiant is low in the north during evening time.
21st-22nd April - The Lyrids.
Again the average hourly rate is expected to be about 10. Viewing should be good with a new moon on the 19th.
11-14th August - The Perseids.
The average hourly rate is expected to be about 60. Conditions are favourable with a new moon on the 16th. In 2002 we viewed the Perseids when the hourly rate was predicted at 60 but in fact counted at least 150 during one and a half hours on the 12th.
20th-22nd October - The Orionids.
An average hourly rate of between 10 and 20 with good visibility as first quarter falls on the 20th.
Late October continuing until late November - The Taurids.
The average hourly rate is between 5 and 10. These are slow meteors from below Pleiades.
16th-18th November - The Leonids.
Unpredictable average hourly rate but with a possibility of a strong shower. Visibiltiy will be good with the first quarter moon on the 19th.
12th-14th December - The Geminids.
Average hourly rate of 60 with good viewing as the first quarter moon is on the 12th.
||Spring equinox 2004: March 20th at 7.00h GMT
Autumn equinox 2004: 22nd September at 16.00h GMT.
||Summer solstice 2004: June 21st at 1.00h GMT
Winter solstice 2004: 21st December at 13.00h GMT.
||Spanish and British summer time begin on March 28th 2004.
Spanish and British winter time begin on October 24th 2004.
Note: Spanish summer time is 2 hours ahead of Greenwich Mean Time and British summer time is 1 hour ahead of GMT.
Spanish winter time is 1 hour ahead of GMT and British winter time equals GMT.
||We say that a planet is in conjunction with another planet or object when the two are in line as viewed from the earth. They are of no real astronomical importance, except that a planet in conjunction with the sun will obviously not be visible in the night sky. Planets in conjunction with each other make an attractive spectacle.
As inner planets, Mercury and Venus have inferior and superior solar conjunctions.
Inferior conjunction is when a planet lies between the earth and the sun and superior conjunction is when a planet lies
behind the sun. The outer planets may only have superior conjunctions with the sun.
Inferior Conjunctions - 17th April, 23rd August and 10th December.
Superior Conjunctions - 4th March, 18th June and 5th October.
Venus - Inferior Conjunction - 8th June 2004 when Venus will also transit the sun.
Last Superior Conjunction - 18th August 2003.
Mars - 15th September.
Jupiter - 22nd September.
Saturn - 8th July.
Uranus - 22nd February.
Neptune - 2nd February.
||Oppositions occur when an outer planet is in the opposite side of the sky from the sun as viewed from the earth. Mercury and Venus can never be at opposition since they are inside of the earth's orbit and, therefore, remain relatively close to the sun.
The planets travel in elliptical, rather than circular, orbits around the sun which means the distance to the sun varies. Oppositions can occur when a planet is closest to the sun (at perihelion) or when a planet is furthest from the sun (at aphelion), or at any time between the two. The most favourable oppositions for viewing are at perihelic opposition as this is also the time the opposing planet is closest to the earth.
Mars appears almost twice as large at perihelic opposition at 56.3 million kilometres from the earth, as at aphelic opposition when it is 100 million kilometres from the earth.
Jupiter - 4th March at -2.5 magnitude in Leo.
Uranus - 27th August at 5.6 magnitude in Aquarius.
Neptune - 6th August at 7.9 magnitude in Capricorn.
Retrograde & Stationary
|As seen from the earth, the motion of all planets is eastwards taken over the whole year. As the earth is also moving, and more quickly than the outer planets, it overtakes them around the time of opposition. At this time the outer planets appear to move backwards against the stars.
The term used to descibe this backwards motion is 'retrograde', as opposed to the normal motion described as 'direct'. The point at which the motion changes from direct to retrograde, or back again, is when a planet is said to be 'stationary'.
In the diagram the direct motion to the east is shown at positions 1,2 and 3, backward motion to the west at 4 and 5, and direct motion to the east again at 6 and 7.
Mars has a direct motion throughout 2004.
Jupiter is stationary on the 4th January in Leo and retrograde through opposition
on the 4th March. It becomes stationary again on the 5th May after which it moves into direct easterly motion.
Saturn, in Gemini, is stationary on the 7th March after which it resumes direct motion
until becoming stationary again on the 8th November and follows a retrograde path.
Uranus, in Aquarius, is stationary on the 11th June after which it will be retrograde through opposition on 27th August. It becomes stationary again on the 12th November and then moves into direct easterly motion.
Neptune, in Capricorn, is stationary on the 17th May, at oppostion on the 6th August and stationary again on the 24th October.
||Venus and Mercury orbit the sun inside of the Earth's orbit. Since neither planet revolves around the sun in exactly the same plane as the earth, they usually do not pass directly in front of the sun. Such a passage, which happens at inferior conjunction, across the sun's disk is called a transit. It is not an eclipse because they appear only as a black dot on the solar disk.
Venus - Transits of Venus are rare, taking place at over 100 year intervals and usually in pairs. The last two transits of Venus were in 1874 and 1882 and the next will occur on 8th June 2004 beginning during early morning, wholly visible from Europe, and again in late June 2012. After that transits of Venus won't occur again until 2117 and 2125.
Mercury - Transits of Mercury are more frequent and take place in May and November. The most
recent transits of Mercury were in 1993 and 1999 and then in 2003 on 7th May. On the latter date a transit commenced
from the upper left-hand side of the sun at about 7.00h SST, crossing the upper part of the sun from left to right, and
left at about 12.45h SST. At this time Mercury was at such a distance from the earth that it was not visible to the naked
eye. It is safe to project the sun's image by means of a small telescope onto a white card. The next transit of Mercury
will be on 8th November 2008.