Mercury at Inferior Conjunction

orbital-positions   Thursday April 20th the innermost planet Mercury reaches inferior conjunction. At inferior conjunction Mercury will move between the Earth and the Sun – much like the position of the Moon at new phase. The graphic to the right shows the planet positions relative to the Earth and Sun for both inner planets and outer planets.

mercury at inferior conjunction   While at this inferior conjunction Mercury will not be directly in line with the Earth and the Sun – on the ecliptic. Mercury has an orbital inclination of 7o with respect to the ecliptic. So like our Moon, Mercury during each complete orbit, will cross the plane of the ecliptic moving north (ascending node) and also moving south (descending node). In this situation Mercury is north of the ecliptic and 6 days away from its descending node on April 26th.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Yuri’s Night 2017

yuri   April 12th 1961 Cosmonaut Yuri Gagarin became the first human to leave the surface of the Earth and orbit our planet. Coincidentally 20 years later, on the same date in 1981 the United States launched its first space shuttle, the Columbia. However April 12th is a date for celebrating the accomplishments of the Russian space program and the cosmonaut who became the first to orbit the Earth. So, on April 12th people around the world will take part in local events in what is known as Yuri’s Night. Use the link to the Yuri’s Night web site to learn more about this event and to see if there is a Yuri’s Night event in your area.

yuri   A few years ago during the 50th anniversary I had an opportunity to work with a group of musicians (Dark Matter) in producing a series of videos about the solar system and our home planet that were then projected as full-dome videos on a Planetarium dome ceiling. Accompanying the videos were two musicians playing their respective instruments (Flute and Clarinet) along with electronic notes, live sampling of their music, and sounds of the interior of a spacecraft. Below is a version of that performance that was entered into a worldwide contest – placed in the top five by the way.


   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

It’s Earthkam Week!

   Several times each year there is an opportunity to request pictures of the Earth to be taken by a camera on the ISS (International Space Station). This is one of those weeks, which actually started last Friday and ends this coming Saturday April 8th. Earthkam is open to educators (parents, teachers, scouts, etc.). On the mission web site there is an application form and there are lessons and activities as well as an archive of the many pictures taken by participants.
   This week I am working with students in several classes at Lee’s Summit High School, and a group of 5th grade students at Westview Elementary School tomorrow afternoon.

   Here are some of the pictures so far.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

March Moon at Perigee #2


   The Moon reaches perigee for the second time, (minimum distance from Earth), this month on Thursday March 30th. At that time the Moon will more or less be at a distance of 28.5 Earth diameters (363,853 km or 226,088 miles) from the Earth.
   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
   On the day of the perigee Moon the 3-day old waxing crescent Moon is over the western horizon at sunset local time, above to the left from Mars, and Mars sets a few hours after the Sun sets.

   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

See A Very Young Moon


   Tuesday evening and Wednesday evening March 28th and 29th there will be opportunities to observe a young and thin waxing crescent Moon. Tuesday as the thin waxing crescent Moon sets it will be approximately 0.94 day young. The following evening, Wednesday, the setting Moon will be approximately 1.94 days young.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Sun Not in Aries But it is The March 2017 Equinox

   Monday March 20th is an equinox day. This means that for those in the northern hemisphere winter is ending and spring has ‘sprung’ (starts). For our counterparts south of the equator summer is ending and fall is beginning. From a geographical perspective we would describe the Sun as being over the Earth’s equator, and as this graphic shows there would be an equal amount of daylight and night on our planet as a result.
    At mid-day on the equator the sun is directly overhead and from that latitude you have no shadow, just a ‘blob-like’ shadow at your feet as this picture of my feet taken at mid-day in Quito Ecuador shows.

    Regardless of your hemispheric preference get outside and cast a shadow!

  Northern hemisphere spring officially (well at least astronomically) begins at 10:29 UT on the 20th (05:29 am CDT) when the Sun reaches the celestial coordinates of 0 hours and 0 degrees as it moves northward along the ecliptic crossing the celestial equator. At this location the Sun is within the constellation of Pisces the Fishes and not just entering Aries the Ram as the pseudoscience of astrology would have you believe.

    To learn more about the celestial coordinates click here to read a previous post about seasons and the equinox.

   Click here to see the online world sunlight map used to make the day/night graphic at the top of the page.

sun-earth   Click here to go to the NASA Sun-Earth Days web site.

   Here is a short series of hourly pictures taken during the day on the September equinox on the equator in Quito Ecuador at Collegio Menor San Francisco de Quito, a private school that I visited and did the SunShIP project with (Sun Shadow Investigation Project).

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Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Duck! Said Scorpius to Sagittarius

   Over the next several mornings, before the Sun rises, the Moon, as it wanes from gibbous to last quarter phase, glides past the stars of Scorpius the Scorpion and Sagittarius the Archer and the ringed planet Saturn.
   Apparently Archery is so loud that Sagittarius didn’t hear the warning and gets a face full of the Moon on the 21st.
   In the background is the Milky Way, but for the most part it will be difficult to see due to the bright reflected light from the Moon.
   Off to the west is Jupiter and Spica. Jupiter has been in retrograde motion since last month and is gradually moving west away from Spica.
   
   
   
   
   
   
   In the background is the Milky Way, but for the most part it will be difficult to see due to the bright reflected light from the Moon.

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Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.