Upcoming Conjunctions Featuring the Moon, Mercury, Venus, Mars and Jupiter
Submitted: Wednesday, 14th January 2009 by Mike Salway
Over the next few months, there are three early morning / dawn conjunctions which are worth getting up early to see.
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What is a Conjunction?
A conjunction is an alignment of 2 or more celestial bodies (usually the moon and planets) in the sky, from our vantage point on Earth. The objects aren't necessarily physically close to each other in space, but from where we see them, when the bodies are grouped close together on the sky we call them in conjunction.
When the objects get so close together that one passes in front of the other from our vantage point, we call that an occultation.
A conjunction doesn't have any particularly special meaning, but they can be interesting to observe because very close conjunctions are quite rare events. It can be very exciting to see two planets in the same field of view of your telescope!
Not only that, but conjunctions, especially with the moon and/or bright planets are involved, are just a lovely spectacle to look at and photograph. Who could forget the beautiful Smiley Face Conjunction of 1st December, 2008?
Where and How Can I See Them?
All three conjunctions appear in the pre-dawn sky low in the East, and are best observed from around 30-60 minutes before dawn local time. They will be able to be seen until the sky brightens too much due to the rising sun.
All you need is a pair of eyes and a good unobstructed Easterly aspect. If you have trees or houses to the East, head to the nearest beach, lake or park to see the conjunction and watch the sunrise as well.
Sky Chart - 23rd February: Moon, Jupiter, Mercury and Mars
The trio of planets actually start converging earlier in February, and on the 18th February, Mars and Jupiter are at their closest - only 33 arc minutes apart (that's just over half a degree, or about the width of the full moon). At that distance, they'll be able to be seen in the same field of view of most telescopes with a wide field eyepiece.
On the 22nd February, the trio of planets is joined by the Moon, and the 4 bodies form an almost straight line in the East.
On the 23rd February, the thin waning Crescent Moon and Mercury are under 1 degree apart, with Jupiter 1.5 degrees below Mercury, and Mars almost 3 degrees further below. See the screenshot below for a sky chart.
Sky Chart - 25th February: Jupiter, Mercury and Mars
On the 24th and 25th February, the Moon departs the scene while Jupiter and Mercury converge closer together. On both the 24th and 25th, they are approx 50 arc minutes apart - just under 1 degree. Mars still hangs around 3 degrees below the pair.
See the screenshot below for the sky chart of the 25th February.
Sky Chart - 23rd April: Moon, Venus and Mars
Skipping forward now, over the next few weeks Jupiter rises earlier and is higher in the sky, while Mars continues it's northward trek. On the 2nd March, Mercury and Mars are just 30 arc minutes (half a degree) apart though they'll both be fairly dim.
Venus appears in the morning sky in early April, and on April 23rd the thin waning crescent Moon joins Venus and Mars for a conjunction with the trio forming a triangle separated by 3-4 degrees.
Uranus isn't too far away, but will be too dim to see naked eye. The Sky Chart below shows the scene.
How Can I Photograph Them?
Photographing these conjunctions is generally quite easy, and most cameras, even the compacts, will do a reasonable job of it however you'll get better results with the cameras that allow you to adjust the settings manually to capture a longer exposure.
In general, you'll need an exposure of around 1 to 4 seconds, so the tripod is a must. Of course with digital, it's very easy to preview your shot afterwards and adjust accordingly - so take lots of shots of varying exposures until the scene is well lit (not underexposed) but not overexposed in your preview screen.
It's easy to take pictures from home with powerlines or rooftops in the view, but the most pleasing shots will be the ones where you make an effort to get to a spot with a nice scenic foreground to compose with the conjunction in the sky. Make sure you give yourself plenty of time to arrive at your location, find the best spot and set up your tripod and camera.
The conjunction isn't over in an instant so you have time to recompose, try different settings etc, but remember that the dawn light can change very rapidly so it might help to go out a day or two before to find the best location and take some practise shots in similar conditions at a similar time of day.
References, Further Reading and Resources