Venus, Jupiter and Mercury this week

Venus, Jupiter and Mercury this week

Postby debbie-moran » Thu May 23, 2013 5:22 pm

Starting today, Venus, Jupiter and Mercury give us a showy "dance of the planets" as they lie in close proximity low in the west soon after sunset this coming week: ... ews_ID=580

Venus and Jupiter will be visible before dark, but Mercury will need more darkness to be detected. Try binoculars for these groupings. Also, check for Venus' and possibly Mercury's phase if you have a telescope. Mercury is very small and phases are harder to detect. Here is some information about "inferior planet" phases:

Terms to know:

Inferior planet: A planet whose orbit is inside the Earth's orbit: Venus and Mercury. These planets have phases as we are able to also see their night time sides.

Superior planet: A planet whose orbit is outside the Earth's orbit: Mars, Jupiter, Saturn, Uranus and Neptune. These planets are presenting only their daytime faces to us. In a few limited parts of its orbit, Mars can be seen as somewhat "gibbous" (not quite full).

Dwarf planet: If it walks like one and talks like one, it is one. These objects are larger than asteroids and smaller than full size planets. Pluto is now considered one. This wikipedia page shows why: ... rf_planets

Superior conjunction: The Sun is between us and the planet. The planet cannot be seen behind the glare of the sun.

Greatest elongation: The planet lies at right angles to us and the sun. In the case of an inferior planet, it shows a half lit phase and is at a high point in our sky.

Inferior conjunction: In the case of an inferior planet, the planet lies between us and the sun. It cannot be seen except in the rare case of a transit. The next transit of Mercury is May 9th, 2016 and the next of Venus is December 11th, 2117. You will need to find the elixir of youth or be reincarnated if you wish to see a transit of Venus. In case you missed it this past June, check out these wonderful images from HAS member Bill Flanagan: ... 1339023774

With a telescope, you can detect Venus' phase and up to four of Jupiter's largest "Galilean Moons," the ones first detected by Galileo when he first turned a small telescope toward Jupiter in January 1610. Here is some great information:

One of the most fun things to observe when looking at Jupiter is the various moon events. When a moon or a moon's shadow is just beginning to cross the edge of the planet, motion can definitely be perceived although it is a little like watching the minute hand on a clock move. Here is a web site with a list of upcoming Jupiter satellite events:

The times are all in "universal time" or the time in Greenwich, England. You need to subtract five hours for CDT and six for CST to observe in Houston. Roman numerals I, II, III, and IV depict the moons in order of their distance from Jupiter: Io, Europa, Ganymede and Callisto. Abbreviations are used to denote the beginning and end of these events: a moon Tra-nsit, a moon Sha-dow transit, an Occ-ultation of a moon as it passes behind Jupiter. Moons can also Ecl-ipse each other. All of these events are fun to plan for and watch in a telescope. Be careful with the times which are not for Houston. You will only be able to observe the events that happen when it is dark enough here.

There is also a link to Red Spot transit times on this site. Jupiter's rotational period is about 10 hours.

There is also now an app for this: ... 07071.html

Let's hope for good weather and enjoy the show!

Debbie Moran, Novice chair
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Re: Venus, Jupiter and Mercury this week

Postby joe-khalaf » Thu May 23, 2013 8:46 pm

Thanks for sharing this, Debbie.

Unfortunately, it seems as though the clouds on the western horizon are going to hamper my attempt at viewing this tonight. I was able to catch a glimpse of Jupiter, but Venus and Mercury were hidden behind the clouds.
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Re: Venus, Jupiter and Mercury this week

Postby debbie-moran » Thu May 23, 2013 10:36 pm

Thanks, Joe. This does seem to be an armchair astronomy week the way things are going.
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Re: Venus, Jupiter and Mercury this week

Postby kim-wiley » Fri May 24, 2013 12:35 am

Thanks a bunch for this post Debbie. We bought a condo on Lake Conroe in Montgomery and this weekend I will be lugging my 10" Dob and binos to the NHAC dark site if the weather permits. This post will help me understand what I'm looking at. :)
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Re: Venus, Jupiter and Mercury this week

Postby debbie-moran » Mon May 27, 2013 1:23 am

Thanks, Kim. Hope you are finding good observing. I am just back from Colorado where I saw the planets on Saturday night. Sunday was cloudy on the ground, but fortunately, I was in a Dreamliner coming back from Denver at just the right time to see Jupiter, Venus and Mercury beautifully above a dash of deep red along the cloud bank below.
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Re: Venus, Jupiter and Mercury this week

Postby jjackson » Tue May 28, 2013 12:55 pm

On Sunday evening a few of us, including some non-astronomy guests, gathered at Geo. Bush Park for some sandwiches, chips, drinks, social time, etc. We struggled with the cloud banks in the west, but persevered and had good looks at Mercury, Venus and Jupiter, arranged in a nice almost isosceles triangle. As a bonus we observed a gorgeous orange rising moon and a couple of us had a quick peek at Saturn via a sucker-hole before the clouds covered it up.
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