Have Some ‘Pie’ – View Some Planets

   Saturday March 14th, 3/14/2020, is perhaps better known as Pi Day given that 3.14, the value for Pi, is also the month and day number. Learn more about Pi and see what NASA has planned for this special day at the NASA Pi Day Challenge web site.
   Saturday the 14th, weather depending, is another day this year when you have a choice of planet viewing – all of the six visible planets in fact. In the early morning skies look east and southeast for a line-up of planets ranging from Mercury, to Saturn, Mars, Jupiter, and the 19-day old waning gibbous Moon. In the evening after sunset Venus shines brightly over the western horizon. Venus is near the outer ringed planet Uranus, but Uranus is not considered a naked-eye visible planet in most skies.
   Mercury, Venus, Mars, Jupiter, and Saturn are all visible, but that’s only five visible planets. So where is the sixth visible planet?

   
   
   

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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Orion, Batter Up!

   Late evening Tuesday March 3rd the 9.5-day old waxing gibbous Moon will be near the stars that make up the weapon held in Orion’s upraised right arm. Sort of looks like Orion is swinging a baseball bat at the Moon. And given the shape of the Moon’s orbit the pitch must be a curve ball!

   
   
   

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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The Moon and the Sisters

   Sunday evening March 1st the 7.5-day old nearly first quarter Moon, but still a waxing crescent Moon, will be 7-8o from the open star cluster the Pleiades. A few degrees from the Pleiades is another open star cluster the Hyades.
   These two open star clusters are part of the constellation Taurus the Bull. The Hyades make up the face of the Bull, while the Pleiades are located on the Bull’s shoulder. The Pleiades are also known as the “Seven Sisters”.
   
   
   

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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The Inner and Outer Solar System

   Friday evening January 31st there is an opportunity to see or at least visualize the inner and outer areas of our solar system. About an hour or so after local sunset look toward the western horizon for the brightly shining inner planet Venus with a -4.0 apparent magnitude. Nearby, about 5o west from Venus, is the outermost of the 8 planets, Neptune. However with an apparent magnitude of 7.94 Neptune would only be visible with an optical aid – the larger the better.
   Look further east and higher for the 7-day old waxing crescent Moon to be between the outer planet Uranus and the Dwarf Planet Eris. About 9o below the Moon is the Dwarf Planet Eris with an apparent magnitude of 18.60 – definitely not naked-eye visible. Above the Moon by about 5o is the outer planet Uranus, just barely visible to the naked-eye with an apparent magnitude of 5.80.

   
   
   

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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Uranus at Eastern Quadrature – 2019

   Thursday January 23rd the position of the planet Uranus with respect to the Earth and the Sun places this ringed planet at what is called eastern quadrature. Uranus is at a 90 degree angle from the Earth. Think first quarter Moon as that is a fair comparison of the relative positions of the Earth, the Sun, and Uranus – or any outer planet. At this position Uranus follows the Sun across the sky from east to west as the Earth is rotating, meaning that Uranus rises after the Sun and sets after the Sun.

   So, where is Uranus? Look over the southwestern horizon after sunset for the stars making up the constellation of Aries the Ram. In particular look for the brighter star Hamal. About 11-12o down to the left from Hamal is the outer ringed planet Uranus.

   With a 5.78 apparent magnitude Uranus is just bright enough to be seen with binoculars as perhaps a very small dot. In the graphic I have enlarged the planet to make it more easy to see. Uranus is at about the naked-eye limit of visibility (6th magnitude)so it would take extremely dark skies to see it without optical assistance. Off to the right and lower are the four stars making up the familiar “Square of Pegasus” asterism.

   
   
   

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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Mars – Uranus at Heliocentric Opposition

   Friday January 3rd Mars and Uranus will reached their respective orbital positions that have them 180o apart. Mars will be located at approximately 215.3o and Uranus at approximately 35.3o of heliocentric longitude. This called heliocentric opposition.

   
   
   

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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January Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Thursday January 2nd. At that time the Moon will be at a distance of 31.71 Earth diameters 251,394 miles (404,580 km) from the Earth.

   On the day of the apogee Moon the 8-day old first quarter Moon rises around noon local time and sets around midnight. At around sunset the Moon will over the southern horizon.

   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.


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November Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Thursday November 7th. At that time the Moon will be at a distance of 31.75 Earth diameters 251,693 miles (405,060 km) from the Earth.

   On the day of the apogee Moon the 11-day old waning gibbous Moon rises during mid-afternoon and sets later the following morning.

   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.


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Visualize the Ecliptic

Above the Terrestrial Planets this Month

   Once in a while the planets are arranged such that they are spread across the sky. The planets are not lined up in a straight line outward from the Sun but rather are arranged along the ecliptic. The ecliptic is the Earth’s orbital path around the Sun and the respective orbit of each planet is inclined from the ecliptic. And this is one of those times when it is easier to visualize the ecliptic. (see graphics below) Click here to read a previous posting about the ecliptic and planet inclination.

   As the animated graphic is showing the terrestrial planets are not arranged in a straight line. This graphic shows the solar system out to Neptune and from this perspective the planets are obviously not in a straight line.


   
   
   

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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Uranus at Opposition – 2019

view-from-uranus
   Monday October 28th the outer planet Uranus reaches a position in its orbit around the Sun when it is on the opposite side of the Earth from the Sun. This coincidentally is known as opposition, and it is an orbital position which only the planets further from the Sun than the Earth may reach.

   At opposition the outer planet rises and sets in a fashion similar to our Moon when it is at full phase, in that the outer planet at opposition rises at sunset and sets at sunrise.

   On the date of the opposition Uranus will be over the eastern horizon after sunset and currently with an apparent magnitude of between 5 an 6 Uranus may be visible with binoculars and certainly with a telescope.

   
   
   

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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