Moon – Venus Morning Conjunction

   This morning despite clouds and thunderstorms moving through the area there were enough breaks in the clouds that allowed for getting a few pictures of the waning crescent Moon and Venus.

   Following the conjunction with Venus this morning watch tomorrow, Sunday morning August 16th, for the 27-day old waning crescent Moon to have moved further east away from Venus. The Moon will be about 6-7o from the ‘Twin’ star Pollux and a few degrees further from the other ‘Twin’ star Castor.

   
   
   
   
   
   
   
   
   
   

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Moon-Venus-M35 Conjunction

   Saturday morning August 15th the thin 25-day old waning crescent Moon will be about 2-3o from the inner planet Venus, and about 3-4o from the open star cluster M-35. All three are located near the feet of the Gemini Twins.
   The contrast in apparent magnitudes is very striking with the Moon shining at -10.7 compared to the -4.3 apparent magnitude of Venus. M-35, with an apparent magnitude of 5.3 will be difficult if not impossible to see with the bright Moon and Venus nearby. Under other conditions M-35 is visible to the naked-eye under dark skies. All three rise 2-3 hours before sunrise local time and will easily fit within the field of view of binoculars. To see just Venus and M-35 wait until tomorrow after the Moon has moved further east, is a thinner crescent and less bright. However Venus will have also moved a bit more than 1o east as it orbits along.
   If you can see the crescent Moon after sunrise it may even be possible to see Venus during the daytime using the Moon as a guide for where to look.

   
   

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August Moon at Ascending Node

   Friday August 14th the thin 25-day old waning crescent 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.
   On the morning of the node crossing the thin waning crescent Moon is positioned about midway between the reddish Aldebaran to the west, and the inner planet Venus to the east.
   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)
   
   
   
   
   
   
   

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Mars as Big as the Full Moon! – No Way!!

A Martian Urban Legend
   “This year, during August, Mars will be at its closest to the Earth; so close, in fact, that it will appear as large as the full Moon.”
   Have you heard this urban legend before? Since 2003, emails describing this myth have circulated the internet usually during July or August. It all started during the opposition of August 2003 when Mars was about as close as it can ever be to the Earth (55,755,723 km – 34,645,000 miles) in a 20-year cycle of varying distances at opposition. Since then, usually around August, misinformation about the appearance of Mars circulates around the internet.

            Here Are Non-alternative Facts:

   This year, 2020, on Tuesday October 13th the outer planet Mars will be at opposition and 7 days (October 6th) after Mars is the closest to the Earth at 38,568,758 miles (62,070,399 km) – this time around. Coincidentally this is 3 months after Earth was at aphelion (July 4th. However this year is not the closest Mars has been from the Earth. The closest, so far, was during August 2003.

   In the time that it takes the Earth to catch up with and move into an opposition position, the outer planets have also been moving eastward relative to the stars in the background. Over time, the constellation where the outer planet is located during opposition and its retrograde loop gradually shift to the east. An opposition is also near the time when the distance between the Earth and an outer planet is around the minimum distance. Keep in mind that because the shape of the orbit is elliptical, this minimum distance will be different each time.

   However, there is an even more conclusive way to show that Mars could never be so close that it would appear as large as the Moon. To see how requires and some basic arithmetic using the numbers from a previous Mars opposition. You will see that Mars could not appear to be as large as our Moon unless some force somehow caused Mars to change its orbital position and literally move closer to Earth.

   On July 31st, Mars will be 57,595,180 km (35,787,986 miles) from Earth. Mars is 6,792 km (4,220 mi.) in diameter. The Moon is 3,475 km (2,159 mi.) in diameter and is an average 384,400 km (238,900 mi.) from Earth. In terms of apparent size our Moon has an angular diameter of 0.5o (30 arc minutes or 1800 arc seconds), while on July 31st Mars has an apparent diameter of 24 arc seconds.
    So with the following calculation using those values (24 / 1800) x 100% = 1.3%) Mars is only 1.3% the apparent size of our Moon.

   Another method to calculate how large Mars will appear as compared to the Moon:
   (Mars’s diameter ÷ Mars’s distance) ÷ (Moon’s diameter ÷ Moon’s distance)

         (4220 / 35787986) / (2159 / 238900) = 0.013 = 1.3%
    In other words, Mars on 31 July will be only 1.3% of the apparent size of the Moon.

   
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August Moon at Apogee

   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Sunday August 9th. At that time the last quarter Moon will be at a distance of 31.72 Earth diameters, 251,469 miles (404,700 km) from the Earth.

   On the date of the apogee the 19-day old waning gibbous Moon will be about 1o from the planet Mars and both very visible over the southern horizon in the 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)

   
   
   
   
   
   
   
   
   

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Moon – Mars Conjunction

   Early mornings before sunrise the waning gibbous Moon is working its way eastward toward new Moon phase. Along the way the 20-day old waning gibbous Moon will be about 1o from the ‘Red Planet’ Mars on Sunday morning August 9th . Both will fit within the field of view of binoculars and should fit within the field of view of a low-power widefield type telescope eyepiece.
   The contrast in apparent magnitude is quite a range, from the Moon’s -12.0 to the -1.22 apparent magnitude of Mars.

   
   
   

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Uranus at Western Quadrature – 2020

   Sunday August 2nd the position of the planet Uranus, with respect to the Earth and the Sun, places this ringed planet at what is called western quadrature. At that orbital position Uranus, and actually any outer planet, is at a 90 degree angle from the Earth as this graphic shows, and also this graphic. Think third quarter Moon as that is a fair comparison of the relative positions of Earth, Sun, and Uranus.
    At western quadrature Uranus leads the Sun across the sky from east to west as the Earth is rotating, meaning that Uranus rises before the Sun and also sets before the Sun.

   
   
   This is a short video clip from a much longer video that I made as part of a live musical performance called “Orbit” at the Gottleib Planetarium in Kansas City Missouri during May 2011.

   
   
   

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Mercury at Western Elongation

   On Wednesday July 22nd Mercury, the innermost planet, will reach its orbital position known as greatest western elongation at 20.1o. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows. Even though it sounds confusing at western elongation for either Mercury or Venus the inner planet will be to the right of the Sun as we view them, meaning that at western elongation an inner planet rises in the east before the Sun rises. And at eastern elongation with the inner planet on the left side of the Sun the inner planet follows the Sun across the sky setting after the Sun sets.

   From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – out to the left (east) from the Sun to eastern elongation, then reverse and move westward (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!

   There is a lot to see and a few things you cannot see on the morning of Mercury’s western elongation. Going by relative apparent magnitudes Mercury (0.33), Venus (-4.43), Mars (-0.89) are all easily visible as bright to very bright star-like objects. On the other hand those not seen with the naked-eye but are still above the horizon in the morning skies include: Uranus (5.80), Eris (18.64), Neptune (7.84), Ceres (7.40)

   
   
   
   
   

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Comet in the Clouds

   This morning, July 13th, the sky was generally overcast with thin status type clouds in most directions, including the northeast where the comet was just starting to appear over the trees marking my local horizon. Fortunately the clouds were still transparent enough for the comet to be just barely visible to the naked-eye, but very visible with time exposure pictures.
   I was hoping to position my camera so that the Baseball player would look as if he were swinging at the comet but the clouds started to thicken in that direction as I moved off the road and into some tall grasses.
   The other planets that were very visible yesterday morning were hidden or blurred by the clouds. Jupiter shined through the clouds but not Saturn or Mars. The Moon light was reflecting off clouds brightening the sky in that direction. And Venus and Aldebaran were somewhat visible but it took a time exposure picture to catch the light from the rest of the stars making the v-shaped part of the Hyades.

   
   
   

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Comet NEOWISE or NEOWOW!!

   Could it get much better than this? Five visible planets (Jupiter, Saturn, Mars, Venus, Earth); Moon-Mars conjunction; Venus-Aldebaran conjunction; 2 outer planets and a Dwarf Planet not naked-eye visible, and Comet 2020 F3 (NEOWISE). Icing on the ‘cake’ would have been to have the ISS orbit through the sky this morning.

   
   
   

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