Auroral activity

Caption for Fig2a: Looking North 17 January 2005 at 21h 52m UT. 15 sec exp. 24mm f/2.8 ISO 800. J Vetterlein, Rousay.

Following on from the early hours of 17 January, the northern sky developed an auroral glow which lead to significant banding by 21h 30m. The effect was compromised by a half-moon high up close to Taurus.

The aurora continued through to the early hours of 18th, though bad weather with snow made observing difficult. A feature of this display has been the predominance of green and blue colours with red showing very occasionally.

Those wishing to photograph the effects should try exposures of up to 30 seconds, even in the presence of cloud.

JV 18/01/05

Solar Activity

Click the images for larger versions

Fig 1a: The Sun imaged 2005 Jan. 17 at 10h 25m UT. 45 x100mm refractor, 1/1000 sec. ISO 400. J Vetterlein, Rousay.

Fig 4: Comet C/2004 Q2 (Machholz) above the Pleiades, imaged 2005 Jan. 11 at 18h 30m . Compare with Fig 3 to appreciate movement of the comet in approximately 24 hrs. A 2 second exposure, 75mm F/1.4, ISO 800. Static camera. JV, Rousay.

Dia. 2 Track of Comet C/2004 Q2 (Machholz) from 07 to 23 January 2005. Positions for 21h 00m UT.

Fig 3. Comet C/2004 Q2 (Machholz) above the Pleiades, imaged 2005 Jan. 10 at 18h 52m . The orange star to the right of the comet is TYC 1796-1306-1, magnitude 4.47. A 2 second exposure, 75mm F/1.4, ISO 800. Static camera. JV, Rousay.

The Sun is currently very active, including a massive sunspot group (Fig1a). This group is readily seen with the naked eye using filters.

Auroral activity is also likely. A fine display was to be seen in the early hours of January 17.

JV 17/01/05

Comet C/2004 Q2 (Machholz)

The comet is now well placed for northern observers passing close to the Pleiades cluster on 7 January.

See Dia.2 for a track of the comet to January 23.

To the naked eye the coma appears as a faint, fuzzy patch some15 arc minutes in diameter (about half the Moon's apparent diameter).

In binoculars the light may appear bluish-green at the centre. (Fig. 3) There is no obvious sign of a tail in instruments of moderate size.

JV 06/01/05

Saturn at Opposition 2005

Saturn's mean synodic period is very close to 378 days, that is to say it comes to opposition approximately 13 days later each year.

Since the previous opposition occurred on 2003 December 31, the next takes place on 2005 January 13. Therefore there was no opposition of Saturn during 2004.

Saturn makes a conspicuous arc with Castor, Pollux and Procyon to the east (left) of Orion (Dia. 1 and Fig. 1) in a sky of many bright stars.

Because of its high declination, as has previously been remarked (see recent archives), the planet spends a great deal of the time above the horizon in our northern skies.

On January 13 Saturn rises at 15h 33m and sets the following day at 09h 13m.

At this opposition Saturn's apparent equatorial diameter will be 20.5 arc seconds compared to 46.5 arc seconds across the rings (major axis).

Note this is a little greater than the apparent diameter of Jupiter at opposition in April. Much later in the year, on November 7, Mars comes to opposition when it will have an apparent diameter almost identical to that of Saturn throughout January.

Dia. 1 Night sky looking south at 22h 00m January 13, 2005. Note Comet Machholz high above Taurus. Click for enlargement

Fig. 1 Saturn in Gemini (below Castor & Pollux), 2004 December 17 at 22h 12m. A 15 sec, exposure 27mm F/2.8 ISO 500. Stars to mag. 8 are visible. The bright star to the far right is Betelgeuse. Procyon bottom middle. M 44 Beehive or Praesepe open cluster is visible lower left. Click the image for an enlargement.

Fig. 2 Saturn. Imaged using CCD and 175 mm Maksutov telescope by Andy Cooke, Finstown, winter 2003/04.

Mars will be favourably positioned for northern observer in the latter party of 2005.

The image of Saturn (Fig. 2) is comperable to the sort of results one would expect from telescopes of three to four times this aperture in the days of film only.