Category Archives: Astronomy

Moon on the Move

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   Over the next few evenings, Saturday December 14th, Sunday the 15th, and Monday the 16th the waning gibbous Moon will orbit eastward starting from about 7-8o south of Pollux to passing about 6-8o from M-44, the ‘Beehive Cluster’, an open star cluster in the constellation Cancer the Crab. By Monday the 16th the waning gibbous Moon will be about 2o from the heart of Leo the Lion, the star Regulus.
   During a 24-hour rotation of the Earth the Moon will have moved approximately 15o eastward. In terms of Moon position that 15o is equal to one hour — (divide 360o by 24 hours = 15o). What this has to do with the Moon’s position is that each day or night the Moon rises about 1 hour earlier. These 3 graphics show the effect of this in that it will be about 1 hour later for the Moon to be more or less in the same spot in the sky relative to the horizon.

   
   
   

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Friday December 13th 2019

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Heidi

Heidi the 13th

   Friday December 13th is Friday the 13th! The number 13 is considered to be bad luck, as is any Friday occurring on a day number that is 13. Neither of which should portend bad things… however!
   For those that keep count, every year will have at least one Friday the 13th, while some years, like this one, have two Friday the 13th. Very interestingly the previous one was 13 weeks ago on – yes, wait for it… in September on Friday the 13th!
   Last year there were three of these days, but on the average those years only happen about 15 times each century. What is kind of interesting is that there are more Friday the 13th days than any other day of the week on a 13th. It is also thought that the Friday the 13th is more or less a modern thing as there seem to be no records or very few accounts of the idea of a Friday the 13th until sometime early during the last century.

   For those that like words, a fear of Friday the 13th is called friggatriskaidekaphobia, while a fear of the number 13 is called triskaidekaphobia.
   


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.


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December Moon at Ascending Node

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   Friday December 13th the 17.5-day old waning gibbous Moon rises between the legs of the Gemini Twins. The Moon will be about 10-11o to the west from the ‘Twin’ Stars Pollux and Gemini. As it is rising the Moon will be crossing the plane of the ecliptic moving north. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.

   Does our Moon actually go around the Earth as many graphics show? 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*
*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   

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.


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Venus – Saturn Conjunction

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   Wednesday evening November 11th look toward the western horizon for a grouping of 3 planets and one dwarf planet. Very low over the horizon and possibly to low to be seen is the outer planet Jupiter. About 7-8o east from Jupiter is the dwarf planet Ceres, however at nearly 9th magnitude and low above the horizon Ceres will be difficult to see, if at all.
   Several degrees east from Jupiter and Ceres is the brightly shining inner planet Venus and about 1-2o from Venus is the outer planet Saturn. These two planets will make a nice contrast in apparent magnitude (Venus: -3.95 Saturn: 0.57) as they easily will fit within the field of view of binoculars.

   
   
   

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.


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Moon Conjunction with Aldebaran

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   Tuesday evening, November 10th, about an hour or so after sunset, the 14.5-day old waxing gibbous Moon will be about 2-3o from the reddish star Aldebaran. Aldebaran is at one end of the v-shaped open star cluster the Hyades in Taurus the Bull.

   
   
   

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.


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A Couple of Morning Planets

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   Early chilly mornings yes, but two planets are visible before the Sun rises. Maybe seeing Mars and Mercury will make it worthwhile? They are both within the realm of the constellation Libra the Scales. As a bonus Dwarf Planet Haumea is also above the horizon but with an apparent magnitude of 17.0 it is virtually invisible without some optical assistance.

   
   
   

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.


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December Moon at Apogee

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   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Thursday December 5th. At that time the Moon will be at a distance of 31.70 Earth diameters 251,311 miles (404,447 km) from the Earth.

   On the day of the apogee Moon the 9-day old waxing gibbous Moon rises during mid-afternoon and sets later the following morning several hours before sunrise..

   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*

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

   
   
   

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.


Also Follow me and other great resources at Feedspot.