Conjunction of Mercury with Venus June 27.

Continuing poor weather throughout most of June has made astronomical work practically impossible.

Here on Rousay, the 27th commenced cloudy but by late morning conditions improved leading to a fine afternoon. It was possible to see both Mercury and Venus in 20x80 binoculars throughout this period.

An image taken using a 100mm refractor is shown in Fig. 1. Mercury is to be seen below Venus a little to the right and much fainter.

Seeing was at its best around 17h - 18h, despite lower altitudes. It was easy to compare the phase of the two planets at powers of x130 and over.

JV 27/06/05

Planetary Conjunction - Mercury, Venus and Saturn

The nearer a planet (or other body) is to the Earth in general the faster it appears to move against the background of stars.

This is not readily appreciated in the case of Mercury, since it is seldom possible to observe the planet against a star background owing to strong twilight.

From June 3, Mercury becomes an evening object, although it is not likely to be seen from high latitudes during this eastern elongation, again due to strong twilight. However, owing to its close proximity to the brilliant Venus, from June 20 to early July, it may be possible to glimpse the planet using binoculars.

Dia. 1 Looking NNW at 22h 20m UT on June 20, 2005.

Dia 1 shows the sky looking NNW at 22 20 UT on the evening of June 20.

Note, the Sun is only 4º below the horizon and Venus barely 3º above the horizon at this time. Even so, it may be possible to locate Venus using binoculars. Thereafter Mercury will close on Venus to be just 4 arc minutes below the bright planet on 27 June.

Throughout Mercury will decrease in brightness being at magnitude -0.1 on the 27 compared to Venus at -3.9. At 08h on the previous day Saturn will be about 1.4º below Mercury and Venus. Saturn offers poor contrast against the sky background and will only be observable in larger instruments.

Mercury continues eastwards moving slightly away from Venus, both planets being in rapid forward motion until Mercury reaches maximum elongation (26º) on July 6. Mercury then moves in towards the Sun, passing 2º below Venus on July 11: it will have faded significantly (mag. 0.7) by then.

The Crescent Moon will appear 2º above Venus on July 8.

JV
01/06/05