Saturn, Spica, and Virgo

saturn   This evening about 1 hour after sunset, local time, look southwest above the horizon for the bluish-white star Spica in the constellation Virgo the Harvest Maiden. Approximately 11 degrees to the east, and to the upper left from Spica, is a slightly dimmer star. Actually that is the planet Saturn. With a small telescope, or even a large one, the rings around Saturn are easily seen as this simulated image of Saturn illustrates.

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

Preview July Issue of Qué tal

voki   As the subject line states, the July preview issue of Qué tal in the Current Skies is now online and available at this temporary web address: http://currentsky.com/2013/jul13/index.html
   It will be at its regular web address in a few days.

   Thank you for your support and encouragement.
   Clear Skies…
   Bob Riddle

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

The Twins, Venus, and Vesta

Click on image to see it full size.

Click on image to see it full size.

   This evening, 22 June, look toward the west for two stars, more or less side-by-side. These are Pollux and Castor, the ‘twin’ stars of the constellation Gemini. Very close to Pollux, the left star, is the planet Venus, and less than 5 degrees away from Venus is the largest asteroid, Vesta. With 7×50 binoculars all three will fit within the field of view as this graphic shows.
   However, and this is a ‘big however’, Venus, and the others are not that high above the horizon around sunset as the banner graphic at the top of the page shows.

   The NASA Dawn mission has recently visited the asteroid Vesta and the spacecraft is currently on its way to the Dwarf Planet Ceres. Click here to go to the NASA Dawn mission web site.
   
   
   Click here to go to the Qué tal in the Current Skies web site for more observing information.

June Solstice

Sun's Apparent Motion Along the Ecliptic

Sun’s Apparent Motion Along the Ecliptic – from Taurus to Gemini

   Northern hemisphere spring comes to an end and its summer begins at 12:04 am CDT (05:04 UT) on 21 June as the Sun ‘reaches’ the celestial coordinates of 23.5oN and 6 hours right ascension. With respect to the Earth’s surface the Sun is described as over the Tropic of Cancer, 23.5oN of the Earth’s equator. At this same time the Sun is still within the boundaries of the constellation Taurus the Bull – but just barely. Interestingly 9 hours later, (9:00 am CDT – 14 UT), the Sun ‘will move’ into the region of Gemini as it crosses the boundary between Gemini and Taurus.
   We know that it is the Earth’s orbital motion around the Sun giving rise to the sun’s apparent eastward motion amongst the stars in the background. This is how the Sun ‘reaches’ a celestial coordinate, how it ‘crosses’ the boundaries between constellations, or how it is ‘in‘ a constellation.
   With respect to the southern hemisphere this is the end of their summer and start of their fall season so thinking globally my preference has been to use the name of the month to designate the season change. Hence the use of the term June Solstice rather than the limited to northern hemisphere term summer solstice.

   Follow the seasons by observing how vegetation changes during 1 year. The video below was produced by an Earth orbiting satellite operated by the NASA/NOAA Suomi National Polar Orbiting Partnership (NPP). It is a really interesting narrated tour of the Earth from orbit over a variety of geographic features and landscapes.

Just had to include this!!

Just had to include this!!

   
   

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

In the Scorpion’s Grip

25 May - 11 pm CDT

25 May – Full Moon

   This past 25 May I described the rising full Moon as in the claws of Scorpius the Scorpion. That evening the full Moon rose at 8:15 pm local Daylight time and was approximately 14.83 days old, or that many days into the lunar cycle.

   This evening the not so full Moon, a gibbous Moon, rises at 5:49 pm and is approximately 12 days old. However as the banner graphic above shows the Moon is more or less back in the claws of the scorpion, as it was when it was at full Moon phase last month.

22 June - Full Moon

22 June – Full Moon

   Curious. Not really, as what is happening is related to the Moon’s orbit and the Earth’s orbit. Basically if the Earth were not revolving around the Sun then the Moon would return to the same phase and position relative to the Earth and the Sun about every 28 days. However since the Earth is in orbital motion while the Moon goes through its own cycle of phases it takes an extra 2 or so days for the Moon to return to the same phase, but not the same position relative to the Earth and Sun. So in two days, the Moon will be at full phase but it will be to the east of where it is this evening.

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

Saturn-Moon-Spica

18 June - 10 pm CDT

18 June – 10 pm CDT

   This evening look toward the southern horizon to see the waxing gibbous Moon in between the blue-white star Spica and one of the four ringed planets – Saturn. All three of which are within the constellation of Virgo the Harvest Maiden.

   
   

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

Give Dad A Quarter Today!

Click on image to see it full size

Click on image to see it full size

   Well not really a quarter as in 25 cents but rather take your Dad outside and share some Astronomy with him. This evening the Moon is at first quarter phase and is located over the southern horizon within the constellation Virgo the Harvest Maiden as the banner above shows. Just to the east, left, from the first quarter Moon is the bright blue-white star Spica, and a little further to the east is one of the ringed planets, Saturn. Over the next few evenings, as the Moon waxes toward full Moon next week, the Moon will continue its eastward motion and will pass by Spica, and then a day or so later pass by Saturn.
saturn   If you have binoculars or a telescope check out Saturn and its large moon Titan.

   
   
   

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

Super Moon – Super Bad Science

Graphic Credit: Heart Touching Fun

Graphic Credit: Heart Touching Fun

   File this under the ‘here we go again’ category on Facebook and other social media where this piece of misleading science is floating around.
   According to graphics like this one from Facebook and presumably re-posted and shared on other social media websites the full Moon of 23 June would be the biggest one this year as well as the closest one for the year – a “Super Moon”. So while the part about closest and largest is correct, using the term “Super Moon” is misleading in the sense that there is nothing for comparison and so there will be folks going outside expecting to see a really large appearing full Moon. But how large? As large as the graphic suggests!!
   So what is a “Super Moon”; how “super” is this next full Moon; and in comparison to other full Moons, how significant, if at all, is this ‘event’?
   A “Super Moon” is a full Moon that occurs very near to its time of perigee, the closest the Moon comes to the Earth for that particular orbit, or month. By definition, “very close” would be when the Moon is less than 10% of its orbital period (about 2.9 days to 3.2 days) from the time of perigee. Use the data in the table below to compare the full and new Moon dates, with the apogee (farthest) and perigee dates and distances. Dates for apogee and perigee are given showing how many days and or hours before or after the date of the new or full moon these two distances occur. The June 23rd perigee date is the same as the date for full Moon while the others are offset.
   Here is an idea – use the apogee dates to determine when we will have a “Super Mini-Moon”!
The 2013 Full Moon

The 2013 Full Moons

   By comparing the 23 June distance with other dates and distances, you will see that there are several “Super Moon”s in 2013. In fact, each year there are from four to six occurrences when the full Moon and perigee are close enough to be considered a “Super Moon” – the full Moon closest to the time for perigee is the “Super Moon” for that year. So a “Super Moon” is not that unique nor worthy of the hype this one will receive since we can have several “Super Moon” ever year.
   Carry this analysis further by comparing dates for full Moon and perigee over a several year period, and you’ll find a pattern in the regularity of “Super Moon” events. How? There are two regular time periods, or cycles, involved in the pattern for “Super Moon”. First, the time period between each full Moon, the synodic month, is approximately 29.53 days; second, the time period between each perigee, the anomalistic month, is approximately 27.55 days. With a two-day difference between these two cycles, there is obviously not a super Moon every month. However, with a ratio of 14 synodic months to 15 perigee periods,the closest of the “Super Moons” to perigee will occur about every 14 months. Because of this ratio relationship between these two cycles, 14 full Moons after the full Moon of June 23, 2013 (356,989 km), there will be the closest full Moon of August 10, 2014 (356,896), which will be followed by the closest full Moon of September 28, 2015 (356,877 km), and so on.

   The above has been adapted from my October 2012 Scope on the Skies column in Science Scope Magazine “Apparent Sizes, or It Was This Big”. Click here to download a copy of that column (PDF).

                    
             Perigee                             Apogee
     (N=New Moon; F=Full Moon '-' = before; '+' = after)
           All times are shown in UT (Universal Time)
Jan 10 10:27 360047 km    N-1d 9h   Jan 22 10:53 405311 km    F-4d17h
Feb  7 12:10 365313 km    N-2d19h   Feb 19  6:31 404473 km    F-6d13h
Mar  5 23:21 369953 km    N-5d20h   Mar 19  3:14 404261 km    N+7d 7h
Mar 31  3:56 367493 km    F+3d18h   Apr 15 22:23 404864 km    N+5d12h
Apr 27 19:49 362267 km    F+1d23h   May 13 13:32 405826 km    N+3d13h
May 26  1:46 358374 km    F+  21h   Jun  9 21:41 406486 km -  N+1d 5h
Jun 23 11:11 356989 km ++ F-   0h   Jul  7  0:37 406491 km -- N-1d 6h
Jul 21 20:28 358401 km    F-  21h   Aug  3  8:54 405833 km    N-3d12h
Aug 19  1:27 362264 km    F-2d 0h   Aug 30 23:47 404882 km    N-5d11h
Sep 15 16:35 367387 km    F-3d18h   Sep 27 18:18 404308 km    N-7d 6h
Oct 10 23:07 369811 km    N+5d22h   Oct 25 14:26 404560 km    F+6d14h
Nov  6  9:29 365361 km    N+2d20h   Nov 22  9:51 405445 km    F+4d18h
Dec  4 10:16 360063 km    N+1d 9h   Dec 19 23:50 406267 km +  F+2d14h

   

  Date/Time of New Moon   Date/Time of Full Moon
   2013 Jan 11 19:45        2013 Jan 27  4:40
   2013 Feb 10  7:23        2013 Feb 25 20:29
   2013 Mar 11 19:54        2013 Mar 27  9:30
   2013 Apr 10  9:39        2013 Apr 25 20:00
   2013 May 10  0:32        2013 May 25  4:27
   2013 Jun  8 15:59        2013 Jun 23 11:34
   2013 Jul  8  7:16        2013 Jul 22 18:17
   2013 Aug  6 21:52        2013 Aug 21  1:45
   2013 Sep  5 11:36        2013 Sep 19 11:13
   2013 Oct  5  0:34        2013 Oct 18 23:38
   2013 Nov  3 12:50        2013 Nov 17 15:17
   2013 Dec  3  0:22        2013 Dec 17  9:29     

Data Table Source: Lunar Perigee and Apogee Calculator. http://www.fourmilab.ch/earthview/pacalc.html

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

EarthKam Opportunity

sally   Students and educators are invited to join NASA for the Sally Ride EarthKAM Summer 2013 Mission from July 9-12, 2013. Guide your students in hands-on research as they program a camera aboard the International Space Station to take pictures of specific locations on Earth. The optional online curriculum at the Sally Ride EarthKAM website is targeted at middle school students, but could easily be adapted for other grade levels.. All students and educators are welcome — including participants in summer and afterschool programs.

   Click here to go to the Sally Ride EarthKam website form more information.
   Click here to go to NASA’s Teaching from Space web site.

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

Thin Moon and Planets

10 June - 9:15 pm CDT

10 June – 9:15 pm CDT

   Look westward this evening, Monday 10 June, at sunset to see the very thin waxing crescent Moon to be about 7 degrees away from the planets Mercury and Venus. Both of the planets and the Moon should almost fit within the field of view of 7×50 binoculars as this graphic shows.

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