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Posts Tagged ‘Opposition’

07/23/2018 – Ephemeris – The importance of Mars in determining the nature of the solar system

July 23, 2018 Comments off

Monday, July 23rd. The Sun rises at 6:19. It’ll be up for 14 hours and 59 minutes, setting at 9:18. The Moon, half way from first quarter to full, will set at 3:41 tomorrow morning.

The accurate observational positions of Mars by Tycho Brahe allowed Johannes Kepler in the early 17th century to discover his three laws of planetary motion. Tycho was the last and greatest of the naked eye astronomers. Kepler befriended Tycho who jealously guarded his observations. It was only after his death in 1601 that Kepler took possession of Tycho’s data. Until then it was believed that planets moved with uniform circular motion, even though they didn’t look like it. Astronomers added circle after circle, called epicycles, to attempt to make their system work. Mars was the worst case. Kepler finally determined that Mars, and indeed all the planets, orbited the Sun in elliptical orbits. That was his first law of planetary motion.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The source if the images below is the talk “Mars 2018” I gave at the Betsie Valley District Library, July, 20, 2018.

Tycho and Kepler

Tycho and Kepler. Artist for Tycho: Eduard Ender (1822-1883). Artist for Kepler, unknown. Source: Wikipedia.

Mars and Earth's orbits

Mars’ and Earth’s orbits to scale and positions of the Earth and Mars July 20, 2018, one week before opposition. Note that Mars’ orbit is decidedly not circular. Credit my LookingUp program.

Retrograde Mars Path 2018

Created using Cartes du Ciel (Sky Charts).

Retrograde motion explained

Created using Cartes du Ciel (Sky Charts).

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05/08/2018 – Ephemeris – Jupiter at opposition

May 8, 2018 Comments off

Ephemeris for Tuesday, May 8th. The Sun rises at 6:23. It’ll be up for 14 hours and 33 minutes, setting at 8:56. The Moon, 1 day past last quarter, will rise at 3:45 tomorrow morning.

At 8:10 p.m. Jupiter will be in opposition, that is opposite the Sun in the sky. Thursday at 8 a.m. it will be its closest to the Earth at 408.9 million miles away, and its biggest in telescopes at 44.8 arc seconds. The Moon averages about 1,800 arc seconds in diameter. So the Moon appears 40 times larger in diameter, meaning you could put 40 Jupiters across the diameter of the moon. Jupiter’s disk is visible in binoculars, along with several of its moons. The moons change position from night to night. Most computer planetarium programs will show the moons for any time past and future. Telescopes will reveal that Jupiter’s face is crossed by bands of contrasting colors of clouds, and the famous Great Red Spot.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Jupiter with its Great Red Spot

Jupiter with its Great Red Spot November 18, 2012 by Scott Anttila.

04/06/2017 – Ephemeris – Jupiter will be opposite the Sun in the sky tomorrow

April 6, 2017 Comments off

Ephemeris for Thursday, April 6th.  The Sun will rise at 7:13.  It’ll be up for 13 hours and 2 minutes, setting at 8:16.  The Moon, 3 days past first quarter, will set at 5:39 tomorrow morning.

The planet Jupiter now rises around sunset.  Tomorrow at 4:58 p.m. it will be officially in opposition from the Sun.  This isn’t some conflict, but the simple fact that Jupiter will be opposite the Sun in our sky.  It then will become an evening planet and in the next month or so will become a dazzling fixture in our evening sky, that it is now later in the evening.  Jupiter is the second brightest planet after Venus, which is now emerging from the morning Sun’s twilight glare.  Watch for it in next Wednesday’s planet report.  Though the second brightest planet Jupiter by far is the largest planet.  It’s mass exceeds the combines masses of all the other planets times two.  Currently NASA’s Juno spacecraft is orbiting it.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

In a telescope the Jupiter system is quite dynamic.  It’s four largest moons change position from night to night, and sometimes while you watch.  The satellites sometimes duck behind Jupiter or through its shadow, or pass in front of the planet, casting their shadow on it.  Close observation of Jupiter reveals details in its clouds.  It rotates in less than 10 hours, over twice as fast as the Earth, which apparently whips the clouds into alternate light colored zones and darker brownish belts.  There’s the Great Red Spot, which last I spotted it has faded to a pale pink, and located in the south edge of the south equatorial belt.  The clouds rotate faster at the equator than at higher latitudes.

Jupiter with its Great Red Spot

Jupiter with its Great Red Spot November 18, 2012 by Scott Anttila.

Shadow annimation

Rocking animation of the early stages of the shadow show on Jupiter. Callisto’s shadow already on the planet while Io’s shadow is just entering. Also Io’s transit is starting., following it’s shadow on the planet. Credit: Scott Anttila

 

03/07/2016 – Ephemeris – Jupiter officially becomes an evening planet tomorrow, celebrating with a double transit of its moons.

March 7, 2016 Comments off

Ephemeris for Monday, March 7th.  The Sun will rise at 7:08.  It’ll be up for 11 hours and 30 minutes, setting at 6:39.   The Moon, 1 day before new, will rise at 6:49 tomorrow morning.

Tomorrow is a busy day astronomically speaking,  Tomorrow night our time there will be a solar eclipse on the other side of the Earth that will be covered by NASA-TV.  I’ll talk more about it tomorrow.  However in the early morning hours Jupiter will reach opposition from the Sun tomorrow at 4:58 a.m.  At opposition the Earth is placed almost directly between the Sun and Jupiter.  It is the time the planet is closest to the Earth in its orbit.  For Jupiter that distance will be 412 million miles (664 million km) away.  It’s apparent diameter will be 44.5 seconds of arc.  One second of arc is one 3,600th of a degree.  The Moon and Sun are about a half a degree or 1800 seconds in diameter.  Even so Jupiter appears as a tiny disk in binoculars, but a very tiny disc.  A few of its 4 large Galilean moons can also be spotted in binoculars.  Jupiter is over 11 times the Earth’s diameter and is twice as massive as all the other planets, asteroids and satellites combined.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Jupiter in the evning

Jupiter at 10 p.m. March 8, 2016 with some of the spring constellations and Canis Major. Created using Stellarium.

Telescopic Jupiter

Jupiter and its moons at 10 p.m. March 7, 2016. Created using Cartes du Ciel (Sky Charts).

Io and Europa and their shadows transit the face of Jupiter

This evening there will be two satellites transiting across the face of Jupiter at the same time: Europa and Io.  The start of Europa’s transit won’t be seen locally, since Jupiter will rise at 6:30 p.m.  Locally, because of Jupiter being low in the sky I wouldn’t expect to spot the transiting satellites or their shadows.  However observers in Europe, whose Jupiter rising has a 5 hour head start on us, will be in perfect position.  In any case this takes a very good telescope to see.  The appearance of Europa and Io in and out of transit can easily be seen in any telescope.  In the table below I give the timing of these events for both the Eastern time zone (us) and Universal Time for others.  Note the transits start on the 7th of March and end on the 8th for Universal Time.

The shadows of the moons themselves will appear very close to the moons, and may be obscured by them because we are just hours from opposition, and looking at Jupiter from nearly in line with the Sun.  That should be a challenge.  Watch for pictures from astrophotographer’s Twitter, Instagram and Facebook sites.

Times for this table are from Project Pluto:  http://www.projectpluto.com/jevent.htm.

Event Eastern Time Zone Universal Time
  Date Time Date Time
Europa Shadow Start* 7 6:08 p.m. 7 23:08
Europa Transit Start* 7 6:11 p.m. 7 23:11
Io Shadow Start 7 7:27 p.m. 8 00:27
Io Transit Start 7 7:28 p.m. 8 00:28
Europa Transit End 7 8:56 p.m. 8 01:56
Europa Shadow End 7 8:56 p.m. 8 01:56
Io Transit End 7 9:42 p.m. 8 02:42
Io Transit End 7 9:42 p.m. 8 02:42
* The Europa Shadow and Transit Start Events cannot be seen in Michigan
because they will occur before Jupiter will rise.

 

 

05/08/2014 – Ephemeris – Saturn will reach opposition from the Sun this weekend

May 8, 2014 Comments off

Ephemeris for Thursday, May 8th.  The sun rises at 6:23.  It’ll be up for 14 hours and 32 minutes, setting at 8:55.   The moon, 2 days past first quarter, will set at 3:37 tomorrow morning.

In two days Saturn will be in opposition from the sun.  That means the Earth will be nearly directly between the Sun and Saturn.  Saturn will be the closest it gets to the earth all year, at 828 million miles (1,334 million km).  Saturn, being about nine and a half times the earth’s distance from the sun, doesn’t vary its distance from the Earth by a great percentage, so it’s a great telescopic object at any time it’s visible.  Mars, being closer and smaller is best seen near the time of opposition.  One effect of opposition is the minimum amount of shadows between the planet and the rings visible.  The shadows will increase until Saturn is 90 degrees from the sun, or quadrature, on August 10th.  Then they will diminish again until it’s in conjunction with the sun.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Saturn's shadows

Saturn at opposition and quadrature showing the maximum shadow at quadrature. Created using Cartes du Ciel (Sky Charts).

Note that the different tilt of Saturn in these two views is due to the fact that Saturn is in the east at opposition and in the southwest at quadrature, helped out by the fact that we’re viewing it from 45 º north latitude.  The different sizes of Saturn is due to Saturn’s greater distance of 919 million miles  (1,481 million km) on August 10th.  The little circle artifact in the center of the planet is due to telling the program that I’m tracking Saturn, so I wouldn’t have to re-find the planet when I shifted 3 months.

04/29/2013 – Ephemeris – Saturn at opposition from the sun

April 29, 2013 Comments off

Ephemeris for Monday, April 29th.  The sun rises at 6:35.  It’ll be up for 14 hours and 9 minutes, setting at 8:45.   The moon, 3 days before last quarter, will rise at 1:11 tomorrow morning.

This past weekend Saturn was in opposition to the sun.  That simply means the earth was more or less directly between the sun and Saturn.  That means Saturn’s at its closest to us at 821 million miles.  The Cassini spacecraft that’s still orbiting Saturn, when it sends pictures and data back to earth still takes about an hour and a quarter for the signals to get here.  Shadows of the rings on the planet and planet on the rings are minimal.  Saturn and the earth have some coincidental properties as seen from the sun.  Saturn is 9.5 times the earth’s distance from the sun.  And Saturn is about 9.5 times the diameter as the earth, so from the sun both the earth and Saturn would appear to be the same apparent size. Cool huh?

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Saturn rising in the evening in May, 2013

Saturn rising in the evening in May, 2013 as rendered by Cartes du Ciel (Sky Charts)