Events

Over the next few weeks Mercury will make a dawn appearance. Look low in the east for a second magnitude object rising ahead of the Sun. It will reach maximum elongation on Sep 19th when it will be over 17° ahead of the Sun.

In the first week of October the planet will disappear back into the Sun's glare. It will reappear in the evening sky during November.

A comet visible to the unaided eye is an anticipated event amongst the amateur astronomy community. Sometimes we know the comet is coming, sometimes we get caught by surprise when a new comet is discovered, occasionally a known comet experiences an outburst and brightens dramatically. Whenever a bright comet offers, telescopes across the globe slew around to enjoy the spectacle, comets are to be enjoyed whenever they appear.

In this case the comet is a well known comet that is making a favorable apparition. Comet 103P/Hartley 2 will pass 0.12AU from Earth, a mere 11 million miles in October of this year. The near approach allowing even a modest comet to become quite bright. Predictions are that the comet will be brighter than 5th magnitude, easily visible to the unaided eye from a dark site.

The comet was discovered in 1986 by Malcolm Hartley. When discovered it became apparent that this was a periodic comet, one who's orbit was regularly within the inner solar system during a 6.4 year orbit, why hadn't it been discovered before 1986?.

Calculations showed that the comet had previously followed an orbit that never brought the comet closer than 1.6AU to the Sun, far enough away from the Sun to lessen the activity of the coma and escape detection. In 1982 the comet swung near Jupiter, where the strong effects of the giant planet's gravity modified the comet's orbit, changing its perihelion to a distance of 0.9 to 1.0AU. The comet now swings much nearer the Sun, the increased solar radiation nearer the sun creating a brighter coma and tail, leading to it's discovery and the occasional much better view for earthbound observers. This fall the comet will make a close approach to Earth, the best appearance since discovery, passing within 0.12 AU (11 million miles) on October 20th, 2010.

Currently the comet is visible in the constellation Andromeda, within easy reach of small telescopes. It is moving westward in the sky and will cross into Cassiopeia and Perseus over the coming month making it well placed for viewers in the northern hemisphere through the close approach. Its path takes it along the Milky Way and near any number of nebulae and star clusters. Around the 9th of October the comet will pass quite close to the Double Cluster, NGC 869 and NGC884, possibly providing a very nice photo opportunity.

While 5th magnitude is not that bright, it should be relatively easy to see under a dark sky. Even in mid-August the comet showed a small tail in photos, hopefully this tail will brighten to allow nice telescopic or even binocular views. In any case it should provide a nice photographic target. Of course when predicting the behavior of comets it is important to remember the words of comet discoverer David Levy... "Comets are like cats, they have tails and do exactly what they want"

This evening Jupiter and the Moon will rise together around 20:00. The nearly full moon, 93% illuminated, will be only 6.5° away from the Moon. The pair will remain visible all night.

Yes, it seems Jupiter got hit again, This is the third time in about a year the big planet has been hit by a significant impact. The video below captures the fireball in a quite a few frames. It may not seem like much in the video, but that fireball is probably hundreds of miles in diameter, possibly much larger. The impact occurred about 18:22UT on August 20th.

And yet again it was amateur astronomers who caught the impact. Indeed all of the recent events were observed by amateurs. This time it was Japanese amateur astronomer Masayuki Tachikawa who caught the event with relatively modest gear, a 150mm refractor and a modified Philips ToUCam Pro (the same model camera I use) to image Jupiter. Hearing of the event, Tokyo amateur Aoki Kazuo went back and examined his data to find he had also captured the impact, thus there is good confirmation that this was a real impact and not an artifact. A number of Jupiter observers have examined other images taken before and after the event and found no impact scar.

This has professional astronomers wondering about the impact rate on Jupiter. Are we seeing an unusual series of events? Or more likely we are discovering that Jupiter gets hit far more often than most had expected, and it is the increased monitoring, mostly by amateur observers, that is revealing the true impact rate.

Today Venus will reach maximum elongation, the furthest from the Sun it will reach this apparition. The planet will be just shy of 50° east of the Sun and 28° above the horizon at 19:00HST, shining brightly at -4.3 magnitude.

After today Venus will begin to slide back into the sunset as it passes between Earth and the Sun, an event called inferior conjunction. Viewers with a telescope will note that the planet is beginning to show a crescent phase, with only 48% if the disk in the sunlight. As the planet nears the Sun it will become a beautiful crescent.

The evening planetary dance also continues unabated, tonight Venus and Mars will be just over 2° apart, with both Saturn and Mercury visible below the pair. High overhead a nearly full Moon (89% illuminated) shines brightly in Sagittarius.

Over the next several nights Mars and Venus will join for one last dance, one of the final performances of the Great Planetary Conjunction of 2010.

The two will pass just under 2° from each other both tomorrow night and the following night. All week they will be quite close, a striking pair in the sunset glow. It will be hard to miss Venus shining at -4.3 magnitude. Attentive observers will note the dimmer Mars, shining at 1st magnitude just above Venus.

Venus will soon begin plunging into the Sun's glare, passing maximum elongation on the 20th. Viewers with a telescope will note is currently about 50% illuminated and will become a crescent in coming months.

The Moon will cut into the dance of Venus and Mars one more time next month. Mark you calendars for Oct 10th and a nice trio of a crescent Moon, Mars and Venus.

Tonight the Great Planetary Conjunction of 2010 starts to wind down, with the Moon moving away from the group of bright planets.

The evening still offers a nice view, with Venus, Mars and Saturn in a 7° triangle and Mercury nearer the horizon below the trio. Venus will dominate the group, shining brightly at -4.3 magnitude. Mars and Saturn have difficulty competing, both shining at a bit dimmer than 1st magnitude.

The dancers still have a few moves left, watch the trio of Venus, Mars and Saturn continue to pirouette. But Mercury has danced it's turn, having passed through maximum elongation on the 8th, and will begin to exit the stage, sinking into the Sun's glare rapidly over the coming week. Saturn will follow after the end of the month, leaving Mars and Venus to one last dance.

This evening is a must see event for dedicated skywatchers. Four naked eye planets and a beautiful crescent Moon join in a swirl of planets in the last glow of sunset.

The performers of this dance could not be better placed, even Mercury is quite high, well out of the Sun's glare. The entire group will be spread along 22° of the ecliptic and will account for four out of five visible planets. The only conspicuously absent planet will be Jupiter, currently rising around 9pm.

Tonight the Moon will be 13% illuminated and just under 6° below a tight triangle of the planets Venus, Mars and Saturn. This trio will be fairly close to each other, within less than 6°.

The entire week offers wonderful photographic opportunities. Time to plan out that perfect conjunction shot. Find a dramatic foreground against which to set the planets... a church steeple, a palm tree and surf, a scene down a lazy river. Conjunctions like this are truly rare events, with a few opportunities each lifetime. Make certain you enjoy this one to the fullest.

The annual Perseid meteor shower peaks today. Unfortunately the predictions for the best of this peak fall during daylight hours for western hemisphere observers, but the Perseids are known for a reliable and broad peak. Begin watching around 23:00 local time as the radiant rises and meteors begin to appear. Rates of up to 100ZHR are possible if the timing is right, 10-20ZHR for the days before and after peak.

The meteor shower is in addition to the spectacular planetary conjunction going on right now and at it's best tonight. This makes today a must observe night for any serious skywatcher.

Tonight will see an increase in activity in the Perseid meteor shower. The traditional peak of this shower occurs tomorrow, August 12th. But since the peak occurs during daylight house (for western hemisphere observers) there is a fair chance of elevated activity in the morning hours of the 12th, late tonight and into the dawn. This could mean rates of up to 100ZHR, one hundred meteors per hour from this reliable shower.

Even if you are not lucky enough to catch a peak, the Perseids should provide rates of 10-20ZHR for much of the week, reason enough to get out to observe.

As the evening planetary dance continues the players are coming together for the main event later this week.

Tonight features a nice triangle of Venus, Mars and Saturn high in the western sky at Sunset. Venus is about impossible to miss, shining at -4.2 magnitude. Look beside the bright planet for Saturn on the right and Mars on the left and above. Mercury is visible between the trio and where the Sun set a few minutes before 19:00.

Today, August 7th, Mercury will reach maximum elongation. The planet will reach 27.4° east of the Sun. Look for a 2nd magnitude object in the glow of sunset. It will be 18° above the horizon, almost due west, at 19:00HST.

High above Mercury this evening will be a nice trio of the planets, Venus, Mars and Saturn. This whole group of planets are well into their evening dance that will take place over coming weeks. Don't miss the evenings of the 11th and 12th when a beautiful crescent Moon will join the evening show.

By the end of the month Mercury will dive back into the Sun's glare, headed for the morning sky and another dawn apparition during September.

Keep an eye to the evening sky today as the Sun sets. The conjunction is just getting better as the trio of Mars, Saturn and Venus slides closer. The trio is hard to miss with brilliant Venus showing where to look. The two starlike objects just above Venus are Mars and Saturn. Drop below Venus towards the horizon reveals Mercury, with nothing else bright or nearby to confuse the issue the innermost planet is easy to identify.

Over the next week the dancers will continue to swirl across the twilight stage. Make a point to take a look each evening as the sky grows dark.

This evening take a moment to look into the fading glow to enjoy four naked eye planets in the sunset.

Venus, Saturn and Mars are visible in a nice trio high in the western sky. Venus is easy to find, shining brightly at -4.2 magnitude. About 3.5° above Venus is Saturn. Another 3.5° to the left is Mars, notably orange compared to the blue-white Venus and the butterscotch colored Saturn.

Mercury is visible much lower to the horizon, but still bright and obvious. The arrangement will be much the same for the next few nights. Keep an eye on the sky as this lineup of planets gets closer to the main event starting in about a week.

A warm summer evening is the perfect time to be out under a dark sky enjoying the stars. All the better is there is a meteor shower to add to the already spectacular show. On the evening of August 12th the Perseid Meteor Shower will peak.

A typical Perseid shower will produce up to 60-100 meteors an hour, what regular meteor observers would call 60-100ZHR This is what a typical observer would see given a dark sky and good conditions, a metric called zenith hourly rate or ZHR. You can estimate this rate by counting the meteors seen in a shorter period. If you count all that you see for ten minutes and multiply by 6 you would have a reasonable estimate of ZHR. As the rate of meteor arrival is irregular it is necessary to count for ten minutes or more to achieve a decent average rate. Conditions such as light pollution or clouds will result in some faint meteors being missed and a lower count.

With new Moon on the 9th, there will be no moonlight to obscure the meteors, a beautiful, dark sky to enjoy through the night. The spectacular planetary conjunction in the evening sky will be at it's peak allowing for a great night of skywatching.