Dance of the Planets

23 May to 11 June - 8:30 pm CDT

23 May to 11 June – 8:30 pm CDT

   In my posting yesterday I described the orbital motions of these three planets without the use of a graphic to help visualize that explanation. This animated graphic that is set to one-day intervals starts with today’s date and then runs for a few weeks. This gives enough time to see how both Mercury and Venus are moving eastward while it appears that Jupiter is moving in the opposite direction, west towards the Sun. Jupiter is in fact moving eastward but considerably slower than the Sun’s apparent eastward motion. The net effect is that Jupiter sets earlier and earlier as the Sun gets closer, and eventually Jupiter moves behind the Sun.

   Both Mercury and Venus were recently on the opposite side of the Sun from the Earth at superior conjunction. Coming from that relative position both planets travel eastward until they reach a point with respect to the Sun that we see as the furthest apart, or the greatest angular separation between the Sun and Mercury or Venus. This happens on either side of the Sun and are known as elongations. Since both planets are on the east side of the Sun they are both heading toward eastern elongation. In the animated graphic above you can see all of Mercury’s orbit on the east side of the Sun including the part where Mercury reaches eastern elongation and heads back toward the Sun. Because Venus is further from the sun it has a longer orbital period around the sun and likewise a longer orbital path so Venus’s orbital path on the graphic extends past the edge.

   

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

3 Amigos!

3planets-text   This evening, Wednesday 22 May, at sunset or shortly after look toward the west northwest horizon to see a trio of planets – Jupiter with Mercury and Venus lower to the right. All three planets will be close enough to be seen in the same field of view of binoculars through the end of this month as this animated graphic shows.

   What is going on? Jupiter is getting closer to the Sun – setting earlier each evening. This is due to the Sun’s apparent eastward motion along the ecliptic which in reality is the Earth’s orbital motion. Since the Earth orbits faster than Jupiter the Sun will catch up with Jupiter as is happening over the next weeks. Meanwhile Mercury and Venus both orbit faster than the Earth and certainly Jupiter so they are able to quickly catch up and pass Jupiter in a manner of days. Both of the inner planets are moving eastward currently.

   Looking Ahead: Starting with 1 June, Mercury and then Venus will pass through a part of the sky near the feet of the Gemini Twins. In this area are several open star clusters that may be visible with binoculars given good sky conditions. Easily seen with low power telescopes with a low magnification or wide field of view eyepiece.

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Moon, Spica, and Saturn

21-23 May - 10 pm CDT

21-23 May – 10 pm CDT

   Tonight, 21 May, and tomorrow the 22nd, the waxing gibbous Moon will pass by the bright blue-white star Spica and the planet Saturn to the east (left) from Spica. This part of the sky is interesting, as are all parts of the sky, however in this area is a menagerie of animals including Corvus the Crow, Crater the Cup (or wine goblet), Hydra the Many Headed Snake, Leo the Lion, and of course the Harvest Maiden Virgo.

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Free Engineering Book

book   Just a quick note to alert you to a free book download for the Kindle. The book, Engineering Stories, is written by an engineer colleague of mine, and contains seven short fiction stories about engineers and how they do what they do. The stories are well written and allow the reader to follow the path an engineer takes from initial brainstorming through the development process to the final product.
   If you are doing anything related to STEM education or are just a curious type then I would recommend this book for you and your students.
   Here is additional information on Ken’s blog. Or download it from Amazon.

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Sun Not in Gemini Today

4:00 p.m. CDT

4:00 p.m. CDT

   Monday 20 May at 4 p.m. CDT the Sun will cross into the constelltion of Gemini the Twins according to the pseudoscience of astrology. However in reality the Sun is within the constellation of Taurus the Bull due to circumstances beyond our control.
   The Earth wobbles on its axis and causes precession of the axes which in turn, among other things, causes the celestial grid system to shift moving the original signs of the zodiac at least one constellation to the west. In effect whatever your zodiacal sign may be according to astrology, you are really the constellation before it according to Astronomy and on this day, the real position of the Sun is still within Taurus the Bull.

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Moon, Meets A Lion

leo1   This evening the first quarter Moon is close to the star Regulus, the brightest star in the constellation Leo the Lion.

   Click here to go to the Qué tal in the Current Skies web site for more observing information.

ISS This Morning

dolphin   Earlier this morning the ISS, International Space station, flew over the midwest in a path that lasted 4 minutes and at its peak the ISS reached 85 degrees in altitude – nearly straight up. The path it followed took it from the southwest horizon across the summer triangle past the star Altair in Aquila the Eagle, towards the east northeast horizon.
   I was hoping to catch the ISS as it flew past some interesting groups of stars like the two small constellations of Sagitta the Arrow and Delphinus the Dolphin however the sky was too bright at this early hour for those stars to show up against the brighter background.
   In this sequence of images the sky at 0530 CDT was fairly bright and there were some high cirrus clouds but the ISS was as bright as Venus appears and was very easy to follow with my camera. The images are 2 second time exposures with an aperture setting of f4, and the lens was backed out to 18mm for a wide field of view.

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   Click here to go to the Qué tal in the Current Skies web site for more observing information.