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03/24/2020 – Ephemeris – Venus reaches greatest eastern elongation from the Sun today

March 24, 2020 Comments off

Ephemeris for Tuesday, March 24th. Today the Sun will be up for 12 hours and 23 minutes, setting at 8:01, and it will rise tomorrow at 7:35. The Moon is new today, and won’t be visible.

Today, around 6 p.m. the planet Venus will reach its greatest eastern elongation from the Sun. That means Venus will appear as far east of the Sun that it can get at an angle of 46.1 degrees. Venus, like Mercury orbits the Sun inside the Earth’s orbit, so is always seen close to the Sun. In telescopes Venus will look like a tiny first quarter Moon. That’s for the same reason. The Sun is illuminating half of the side we can see. Venus is moving directly toward us now, at a distance of 66.5 million miles (117 million km). As Venus approaches us, it will grow in size in telescopes, becoming larger in appearance than Jupiter the largest planet and a thinner and thinner crescent. It will leave the evening sky, passing between the Earth and the Sun, only 27 million miles (43 million km) away on June 3rd.

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

Addendum

Venus at greatest eastern elongation

Venus at greatest eastern elongation seen tonight at 8:20 p.m. The red line its orbit if we could see it tonight. Venus will be moving to the right and down in the coming days. Created using Stellarium.

03/19/2020 – Ephemeris – Mars will pass Jupiter tomorrow morning

March 19, 2020 Comments off

Ephemeris for Thursday, March 19th. Today the Sun will be up for 12 hours and 7 minutes, setting at 7:54, and it will rise tomorrow at 7:44. The Moon, 3 days past last quarter, will rise at 6:31 tomorrow morning.

Spring will start today, or rather this evening 10 minutes before midnight. But today I’d like to talk about something more immediately visible than the vernal equinox, that is the conjunction of Mars passing Jupiter tomorrow morning. In astronomy a conjunction means that the two planets pass north and south of each other. On Earth we’d say that they had the same longitude. In the sky that would be the same right ascension. The term longitude in the sky is given to measurements along the ecliptic or Sun’s path in the sky, which were more important to ancient astrologers interested more in the motions of the planets, which hung close to the ecliptic. On Earth, measurement of longitude is made from Greenwich Observatory in England, in the sky right ascension is reckoned from the point in the sky where the Sun will be at 11:50 this evening.

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

Addendum

Jupiter and Mars in conjunction near Saturn

The three morning planets in the southeast at 7 a.m. Friday March 20, 2020. Appearing in the southeast means that Mars being south of Jupiter does not mean that it is not directly below Jupiter. See the chart below. Created using Stellarium.

Jupiter and Mars in conjunction near Saturn with equatorial grid

The same chart as above with celestial equatorial coordinates. The lines labeled 19h and 20h near the top are right ascension lines. The lines crossing them are lines of declination which are analogous to latitude on the Earth. Created using Stellarium.

Slightly off topic

Right ascension is measured in hours, minutes and seconds.  Because the Earth revolves within the starry sky in 23 hours, 56 minutes and 4 seconds, special clocks can be made to run fast by that amount.  These are sidereal clocks, and tell sidereal time or star time for one’s location on the Earth, which is the right ascension of the sky or celestial sphere on that’s due south or more properly on the meridian.

Time panel for LookingUp

The time panel from my LookingUp program showing date, time and the sidereal time that corresponds to it for my location.

06-18-2019 – Ephemeris – Mercury and Mars will be seen together tonight

June 18, 2019 Comments off

Ephemeris for Tuesday, June 18th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 1 day past full, will rise at 10:49 this evening.

This evening the Planets Mercury and Mars will appear less than a moon-width apart in the evening twilight. Mercury, the brighter of the two, by a factor of 4 times, will be visible first, at about 10:15 p.m. very low in the west-northwest. Mars will be immediately below it by less than the width of the Moon. At that time they will be a bit less than the width of your fist held at arm’s length above the horizon. Binoculars are the best way to spot them. Mercury will continue to move eastward in the sky away from Mars. Until after it reaches its greatest separation from the Sun on the 23rd. It will then head back and pass at a much greater distance below Mars on July 5th. This is the best chance to spot Mercury in the evening sky this year.

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

Addendum

Mercury-Mars Conjunction

Mercury and Mars this evening at 10:30 p.m., June 18, 2019. Created using Stellarium.

05/06/2019 – Ephemeris Extra – The Eta Aquariids – Halley’s Comet never really left

May 5, 2019 Comments off

In 1986 Halley’s Comet swam through our skies for the 28th time since the Chinese first recorded it in 240 BCE. It was not especially impressive, considering the week when my family met a group of Leelanau School students in the Florida Keys the week in April 1986 to view and photograph the comet at it’s closest to the Earth of 44 million miles. It turned out that that week the comet lost its tail, probably due to a coronal mass ejection from the Sun. Halley’s Comet was much more impressive a month later. I’ve seen more impressive comets before and since.

Comet Halley's path thru the inner solar sstem

Comet Halley’s path through the inner solar system in 1985-86. Created using my LookingUp program.

Halley’s Comet has been swinging around the Sun countless times before the Chinese first recorded it. The illustration above shows the last time the comet entered the inner solar system in 1986. The comet’s path is from upper right to lower left. When the comet passes within about 3 astronomical units of the Sun, that is 3 times the Earth’s distance from the Sun, the ices in the comet begin to sublimate, escaping from the comet’s nucleus which liberates dust and larger solid material. The gasses and dust form the comet’s ion and dust tails. The larger material, gravel sized bits, end up in and around the comet’s orbit, and over time are spread out around and near the comet’s orbit. Halley’s orbit crosses the Earth’s orbit twice, inbound and outbound. In both cases these crossings are close enough to the plane of the Earth’s orbit to produce meteor showers.

On the inboard leg of the orbit it produces the Orionid meteor shower that peaks on October 22nd. A meteor shower is generally named for the point in the sky they seem to come from, be it a constellation or star. The point, called the radiant, moves during the days or weeks the shower is visible. The Orionids are named for the constellation Orion. The radiant is near his upraised arm.

The center of the outbound meteoroid stream crosses the Earth’s orbit where the Earth is on May 6th. Though they have a broad peak of about 5 days. This meteor shower is visible from April 19th to May28th. During that period the radiant points drifts quite a bit to the east. There are several meteor shower radiants in Aquarius, so they are named for the nearest star at peak.

Motion of Eta Aquariid Radiant

Motion of the Eta Aquariid radiant from April 20 to May 25. The triangle with the star near the center near May 05 is the asterism the Water Jar, a part of Aquarius. Eta Aquarii is the triangle star to the left. Source: PDF version of the International Meteor Organization 2019 Meteor Shower Calendar: https://www.imo.net/resources/calendar/

Though the Moon is new for this shower, the meteoroids are coming from near the direction of the Sun, so there is only an hour where the Eta Aquariids are best seen. For Northern Michigan the radiant rises at 3:30 a.m. on May 6th. Astronomical twilight begins at 4:30 a.m. when the sky begins to brighten. This meteor shower is best seen from the southern hemisphere.

12/24/2018 – Ephemeris – The Star of Bethlehem a possible solution

December 24, 2018 Comments off

Ephemeris for Christmas Eve, Monday, December 24th. The Sun will rise at 8:18. It’ll be up for 8 hours and 48 minutes, setting at 5:06. The Moon, 2 days past full, will rise at 7:35 this evening.

Last Thursday I talked about the timing of Jesus’ birth being just before Herod the Great’s death, which I suggested was in 1 BC due to a lunar eclipse. So the Star of Bethlehem could appear several years later than the triple conjunction of Jupiter and Saturn in 7 BC that’s been popular. In 3 and again in 2 BC there were star-like conjunctions or apparent joinings of the planets Jupiter and Venus against the backdrop of constellation of Leo the Lion. A lion is related to Judah,, son of Jacob by a blessing the latter gave his 12 sons in Genesis. The first conjunction occurred in August of 3 BC in the morning sky. In June the next year the two planets got together again, this time in the evening sky, a month or more after Jesus would have been born in the lambing season of spring.

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

Addendum

August 12, 3 BC conjunction

Here is an animation created using Stellarium of Jupiter and Venus, the brighter of the two seeming to pass very close on August 12, 3 BC in the early morning twilight.  Regulus is the brightest star in Leo.

The above conjunction would occur near Jupiter’s heliacal rising, its first appearance in the morning sky after having left the evening sky.  An event signifying beginnings or birth in many cultures.  10 months later they again conjoin, this time much closer.

The second appearance of the "Star"

On June 16th 2 BC, this time in the evening, Venus and Jupiter seem to coalesce as one, at least to the naked eye.  Created using Stellarium.

I’ll add in the triple conjunction  of 7 BC just to cover all bases.

Triple conjunction

The Jupiter-Saturn triple conjunction of 7 BC. This animation is at 5 day intervals.  The Moon will be popping in and out of the view. It end in February of 6 BC when Mars and the Moon enter\s the picture. Click on the image to enlarge. Created using Cartes du Ciel.

To the problem i mentioned in my December 20th post is if Herod died in 1 BC the flight to Egypt of the Holy Family would have lasted, maybe 9 months or a year.  The traditional length of the flight to Egypt is 2 years.  If we gave Herod, according to Josephus, 16 months between the lunar eclipse in January of 1 BC and Passover of AD 1 when Herod died, then the Flight to Egypt could be 2 years in keeping with tradition.  My December 20th post is here: https://bobmoler.wordpress.com/2018/12/20/.

So was the Star the triple conjunction of 7 BC, the two conjunctions of 3 and 2 BC, a miraculous event outside of nature, or a bit of mythology tucked into Matthew’s Gospel.    We will probably never know.

Have a very merry and safe Christmas.

04/02/2018 -Ephemeris – Mars is appearing to pass Saturn in the morning

April 2, 2018 Comments off

Ephemeris for Monday, April 2nd. The Sun will rise at 7:21. It’ll be up for 12 hours and 49 minutes, setting at 8:11. The Moon, 2 days past full, will rise at 10:40 this evening.

At 3:02 this afternoon the planet Mars will pass the planet Saturn. The event is called a conjunction, which simply means they are on nearly the same line of sight from the Earth, and nothing more. It will make a pretty sight tomorrow morning before the sky gets too bright with reddish Mars being just below Saturn, by a bit less than 3 moon widths. Conjunctions of these two planets occur at intervals of two years give or take, since it involves the orbital motions of Mars and Saturn while viewing them from a third planet also orbiting the Sun.

Currently both planets are moving eastward against the stars. Saturn will slow and stop its motion on April 18th, while Mars will continue until June 28th. They will track westward for a while. This is because the Earth will be passing these planets this summer, which is called opposition (from the Sun).  Saturn will reach opposition on June 27th, Mars on July 27th.  Mars closest approach will occur four days later at a distance of 35.76 million miles  (57.59 million kilometers).  This is Mars’ closest approach to the Earth since August 27th, 2003.  Expect the return of the Mars hoax emails this summer.

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

Addendum

Conjunction animation of Mars passing Saturn

Conjunction animation of Mars passing Saturn at daily intervals at 6 a.m. for March 30 to April 4, 2018. This will occur above the Teapot asterism of the constellation of Sagittarius. Created using Stellarium and GIMP.

I covered the Mars hoax 5 years ago here on an August 27th when Mars was nowhere close to us.

03/15/2018 – Ephemeris – Mercury at greatest separation (elongation) from the Sun today

March 15, 2018 Comments off

Ephemeris for the Ides of March, Thursday, March 15th. The Sun will rise at 7:55. It’ll be up for 11 hours and 53 minutes, setting at 7:48. The Moon, 2 days before new, will rise at 7:45 tomorrow morning.

Today the planet Mercury will be at its greatest separation east from the Sun. It is called its greatest eastern elongation from the Sun. It is at an angle of 18.4 degrees from the Sun. It will be seen in the west about 8:15 for about an hour before it sets. It will be above right of the much brighter Venus. Mercury is probably at its best place to be observed than any time this year, with eastern elongation happening near the vernal equinox and is placed at a high angle above the Sun. The best morning appearance of Mercury will be its greatest western elongation on August 26th, almost a month short of the autumnal equinox, where it won’t be placed at as great an angle above the rising Sun.

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

Addendum

Venus and Mercury

Venus and Mercury photographed last night at 8:20 EDT March 14, 2018. Did some tweaks to bring out Mercury in GIMP. Canon EOS Rebel T5, 75 mm, though reduced by 67%; f/4, 1/400 sec., ISO 1600. Click on image to enlarge. Click on image to enlarge. Credit Bob Moler.

Venus and Mercury positions tonight.

Stellarium’s showing of Venus and Mercury at 8:15 p.m. March 15. 2018.

Note in the above image, the steepness of the ecliptic (plane of the Earth’s orbit) is to the horizon in the spring.  Its angle to the celestial equator is 23.5°.  The angle the celestial equator makes with the horizon is your co-latitude (90° – your latitude).  At my location my latitude is 44.7°, so the celestial equator meets the horizon at 45.3°.  On the March  equinox the ecliptic, near where the planets hang out, reaches its most vertical at nearly 70°.  This makes planets, including Mercury appear higher in the sky near sunset, and as they set, moving parallel to the equator, will stay up their longest.

September equinox sunset

Celestial equator and ecliptic at the September equinox showing how low it appears. Created using Stellarium.

On the September  equinox the ecliptic, near where the planets hang out, reaches its most horizontal at near 22°.  This makes planets, including Mercury appear lower in the sky near sunset, and as they set, moving parallel to the equator, will set shortly after the Sun.  This September Venus happens to be approaching its inferior conjunction and is very close to the Earth.  This exaggerates its orbital inclination. in this case shows the planet a good deal south of the ecliptic.

Spring equinox sunrise

At the spring equinox close morning planets to the Sun will be hard to spot, being low to the horizon.

Ecliptic on the autumnal equinox

Celestial equator and ecliptic at the September equinox mornings showing how high it appears. Created using Stellarium.

Update

The angles of the elongation of Mercury at the equinoxes

The angles of the elongation of Mercury at the equinoxes. Click on image to enlarge. Created using my LookingUp program.

Due to the eccentricity of Mercury’s orbit and its orientation with respect to the Earth’s positions at the equinoxes, observers on the southern hemisphere of the Earth get a better view of Mercury than us northerners.

(I created a similar diagram for posting yesterday, but found right before the scheduled posting time that it was incorrect in its orientation, so I redid it this morning.)