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07/10/2020 – Ephemeris – The constellation Cygnus the swan

July 10, 2020 Leave a comment

This is Bob Moler with Ephemeris for Friday, July 10th. Today the Sun will be up for 15 hours and 20 minutes, setting at 9:28, and it will rise tomorrow at 6:08. The Moon, 2 days before last quarter, will rise at 12:52 tomorrow morning.

Fairly high in the east at 11 p.m. Is the constellation of Cygnus the swan, flying south through the Milky Way. It is also called the Northern Cross. At the left, the tail of the swan or the head of the cross is the bright star Deneb, one of the stars of the Summer Triangle. The next star right is Sadr the intersection of the body and the wings of the swan seen in flight, or the intersection of the two pieces of the cross. There are two or three stars farther to the right that delineate the swan’s long neck or upright of the cross, that ends with the star Alberio in the beak of the swan or foot of the cross. The crosspiece of the cross extends to the stars on either side of the intersection star Sadr, while the swan’s wings extend to a couple more stars each.

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

Addendum

Cygnus finder animation

Animated Cygnus finder chart. Included also are, beside Deneb, the other stars of the Summer Triangle: Vega and Altair and their constellations Lyra the harp and Aquila. See if you can find them. Click on the image to enlarge it. Created using Stellarium.

07/09/2020 – Ephemeris – The constellation of Lyra the harp

July 9, 2020 Leave a comment

Jul 9. This is Bob Moler with Ephemeris for Thursday, July 9th. Today the Sun will be up for 15 hours and 22 minutes, setting at 9:29, and it will rise tomorrow at 6:07. The Moon, 3 days before last quarter, will rise at 12:30 tomorrow morning.

High in the east at 11 p.m. can be found a bright star just above a small, narrow, but very distinctive parallelogram of stars. They are the stars of the constellation Lyra the harp. The bright star is Vega the 5th brightest night-time star. To the Romans the star Vega represented a falling eagle or vulture. Apparently they never made the distinction between the two. It is a pure white star and serves as a calibration star for color and brightness. The harp, according to Greek mythology, was invented by the god Hermes. The form of the harp in the sky, is as he had invented it: by stretching strings across a tortoise-shell. Hermes gave it to his half-brother Apollo, who in turn gave it to the legendary musician Orpheus.

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

Addendum

Lyra

Lyra as a tortoise shell harp. Created using Stellarium and free clip art.

07/07/2020 – Ephemeris – New Comet NEOWISE (C/2020 F3) is visible in the morning

July 7, 2020 Leave a comment

This is Ephemeris for Tuesday, July 7th. Today the Sun will be up for 15 hours and 24 minutes, setting at 9:29, and it will rise tomorrow at 6:06. The Moon, 2 days past full, will rise at 11:37 this evening.

Comet C/2020 F3 (NEOWISE) is visible in the morning now, and quite bright. At 5 am in twilight it will be very low in the northeast tomorrow morning, below the bright star Capella. I’ve seen a photograph of it showing a tail. Over the next week it will be moving northward along the horizon at 5 am and fading as it goes. Then it will become visible in the evening sky next week. It is best seen in binoculars, though it can be spotted with the naked eye. One needs a low northeastern horizon. That’s the problem with comets: they’re brightest when close to the Sun, and can be seen best only when the Sun isn’t up. So that leaves morning or evening twilight, unless they are a huge comet like Hale-Bopp of 23 years ago that doesn’t get close to the Sun.

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

Addendum

Comet NEOWISE in the morning

Comet NEOWISE starting at 5 am February 8, 2020. Every second date has month-day and predicted magnitude. The sky will be a bit higher each morning. Created using Cartes du Ciel (Sky Charts)

07/06/2020 – Ephemeris – The southernmost star of the Summer Triangle, Altair

July 6, 2020 Leave a comment

This is Bob Moler with Ephemeris for Monday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 1 day past full, will rise at 11:02 this evening.

The southernmost star of the Summer Triangle is Altair, high in the east-southeast. The other two stars of the triangle are Vega nearly overhead in the east, and Deneb high in the east-northeast. Altair is the closest of the three at a distance of 16.7 light years away. One light year is nearly 6 trillion miles. Altair is 10 times the brightness of the Sun. If seen at Altair’s distance, the Sun would only be as bright as one of the two stars that flank it. What is rather different about Altair is its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in about 9 hours, The CHARA Interferometer at Mt. Wilson has actually imaged its squashed disk in the infrared. Our Sun’s a slow poke, taking nearly a month to rotate once.

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

Addendum

Summer Triangle. Created using Stellarium.

Summer Triangle. Created using Stellarium.

Altair

Lines added to show the rotation axis. Credit: Zina Deretsky, National Science Foundation.

 

 

06/26/2020 – Ephemeris – The stars known as the Horse and Rider

June 26, 2020 Comments off

Jun 26. This is Bob Moler with Ephemeris for Friday, June 26th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:32, and it will rise tomorrow at 5:59. The Moon, 2 days before first quarter, will set at 1:28 tomorrow morning.

The most interesting star in the Big Dipper is Mizar and its dim companion Alcor. It is the second star from the end of the handle, where the bend in the handle takes place. Folks with good vision can see the dimmer star right next to Mizar. In ancient times it was used as an eye test for visual acuity for warriors. As such it was known as the “Horse and the Rider”. Mizar is second magnitude, in the second rank of star brightness invented by the Greek astronomer Hipparchus in the 2nd century BC. He ranked stars in 6 classes, from first magnitude for the brightest to 6th for the dimmest visible to the naked eye. Alcor comes in at 4th magnitude. It does suffer a bit by being very close to Mizar which is 6 times brighter.

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

Addendum

Mizar finder animation

Mizar finder animation for the Big Dipper’s orientation in late June at 11 pm where I live or an hour and a half after sunset. Created using Stellarium and GIMP.

Mizar and Alcor as they would appear in a telescope

Mizar and Alcor as they might appear in a telescope. Mizar is a binary star in a telescope. The other star in the field is apparently a background star. The brighter star of Mizar is Mizar A, while the dimmer is Mizar B. It turns out that Mizar A and B plus Alcor are all spectroscopic binaries, meaning the companion stars are too close to resolve in telescopes, but whose motion shows up in the spectra of the stars. Mizar and Alcor are around 80 light years away. Created using Stellarium.

06/24/2020 – Ephemeris – Let’s look at the naked-eye planets for this week

June 24, 2020 Comments off

This is Bob Moler with Ephemeris for Wednesday, June 24th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 3 days past new, will set at 12:27 tomorrow morning.

Let’s look at the naked-eye planets for this week. Jupiter now rises in the evening, tonight it’s at 10:42 pm in the east-southeast. Saturn will rise 18 minutes later at 11pm right behind Jupiter. Mars, is stretching its lead left of Saturn and will rise at 1:36 am in the east. Its now down to 83.4 million miles (134.3 million km) away, as the Earth slowly overtakes it at the rate of about 4 million miles (6.4 million km) a week. Jupiter and Saturn will be hanging out between Sagittarius and Capricornus this year while Mars is slowing its rapid eastward motion now two constellations over in Pisces. Finally, Venus will rise at 4:26 am in the east-northeast low in the twilight as our Morning Star.

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

Addendum

The Moon as seen through binoculars or small telescope

The Moon as seen through binoculars or small telescope tonight June 24, 2020. Note earthshine on the night side of the Moon. Created using Stellarium.

Jupiter & Saturn at midnight

Jupiter & Saturn at midnight. Note the Teapot of Sagittarius to the right of Jupiter and the stars of Scorpius including Antares farther right. Click on the image to enlarge. Created using Stellarium.

Four of the five naked-eye planets stretched out on this panorama from northeast to southwest at 5 am tomorrow morning June 25, 2020. Click on the image to enlarge. Created using Stellarium.

Telescopic planets

The planets as seen in a telescope (north up) with the same magnification tomorrow morning June 25, 2020. Apparent diameters: Jupiter, 46.96″; Saturn, 18.28″, rings, 42.58″, Mars, 10.99″, and Venus 47.10″. Mars also shows an enlargement showing surface detail. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on June 24, 2020. The night ends on the left with sunrise on the 25th. The closeness of Jupiter and Saturn in the morning sky unfortunately overlays planets and labels. Click on the image to enlarge. Created using my LookingUp program.

06/11/2020 – Ephemeris – The Moon passes Mars starting tomorrow morning

June 11, 2020 Comments off

This is Ephemeris for Thursday, June 11th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, 2 days before last quarter, will rise at 2:04 tomorrow morning.

In the morning sky tomorrow and Saturday morning the Moon will be passing Mars. Actually you’ll see a before and after shot of them because the Moon’s passage south of Mars will occur about 6 pm tomorrow evening when we can’t see them. Mars is getting brighter as we, on the Earth approach it. It is also getting larger in telescopes. On Wednesdays on this blog besides showing where the planets are, I show what they might look like in a small telescope. Until this week Mars appeared too small for me to show detail on Mars. However it is now large enough to maybe see a polar cap and some other detail depending on telescope size. Mars will double its apparent size between now and October.

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

Addendum

Moon and Mars animation

Moon and Mars animation for 5 am Friday June 12, 2020 and 4:56 am Saturday June 13th. The Jump between of 23 hours, 56 minutes and 4 seconds is the Earth’s sidereal day, the true period of its rotation in relation to the stars. Note that the few stars visible do not move, but Mars and the Moon do. Created using Stellarium and GIMP.

06/08/2020 – Ephemeris – Tomorrow’s Moon and the morning planets

June 8, 2020 Comments off

This is Ephemeris for Monday, June 8th. Today the Sun will be up for 15 hours and 29 minutes, setting at 9:26, and it will rise tomorrow at 5:57. The Moon, 3 days past full, will rise at 12:28 tomorrow morning.

This afternoon the Moon will pass south of Jupiter, and this evening it will pass south of Saturn. By tomorrow morning the Moon will be to the lower left of both of them. However to see them one should get up by 5 am. By 5:30 the planets will be pretty much lost in twilight. The Moon should still be easily visible low in the south at that time. A careful observer, over time, may notice that both Jupiter and Saturn are moving slowly westward, rather than their normal eastward movement. We call this motion retrograde motion. This motion baffled the ancient Greeks, who thought the Earth to be stationary and the planets moved uniformly in perfect circles. They kind of solved it by adding smaller circles to the original ones.

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

Addendum

Moon and morning planets

The Moon and morning planets at 5 a.m. tomorrow morning in the eastern US at 5 am, June 12, 2020. Created using Stellarium.

06/05/2020 – Ephemeris – A penumbral eclipse of the Moon for the eastern hemisphere of Earth today

June 5, 2020 Comments off

This is Ephemeris for Friday, June 5th. Today the Sun will be up for 15 hours and 26 minutes, setting at 9:24, and it will rise tomorrow at 5:57. The Moon, at full today, will rise at 9:32 this evening.

There will be a penumbral eclipse of the Moon this afternoon. We won’t get to see it because the Moon won’t be up yet. The eclipse, such as it is, will be only visible from the eastern hemisphere of the Earth like Asia. Even then there won’t be much to see. In a penumbral eclipse the Moon only enters the Earth’s outer shadow, called the penumbra where sunlight is only partially cut off. Observers on the affected parts of the Moon would see the Sun only partially eclipsed. And anyone whose seen a partial solar eclipse will tell you that it doesn’t get that dark. So most penumbral eclipses go unnoticed unless one is told about them. This one less than 60% of the Moon will be immersed in the Earth’s penumbral shadow.

There will be two more penumbral lunar eclipses this year, both visible from the United States: July 5th when only 35% of the Moon’s diameter is immersed in the penumbra, and November 30th when 83% is immersed.

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

Addendum

Lunar eclipse chart

Lunar eclipse chart for the penumbral lunar eclipse of July 5th, 2020. Unfortunately for Michigan it will occur between 1:45 and 5:04 pm before the Moon rises tonight. Click on the image to see the original pdf page from NASA. Credit NASA GSFC/Fred Espenak.

Eclipse visibility map

Eclipse visibility map. Areas on the Earth where the eclipse is visible. Credit NASA GSFC/Fred Espenak.

06/04/2020 – Ephemeris – Mercury is at it’s greatest separation from the Sun today

June 4, 2020 Comments off

This is Ephemeris for Thursday, June 4th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:24, and it will rise tomorrow at 5:58. The Moon, 1 day before full, will set at 5:53 tomorrow morning.

Today at 9 am the planet Mercury will be at its greatest eastern elongation. That’s what astronomers call it. Implied is that it is at its greatest angular separation east of the Sun. Mercury, and also Venus have orbits inside Earth’s orbit of the Sun. For that reason they are called inferior planets. Therefore they never stray far from the position of the Sun in the sky. From around our latitude near 45 degrees north, we never see Mercury outside of twilight. Mercury has a remarkably elliptical orbit ranging from 29 million miles (47 million km) to 43 million miles (70 million km) from the Sun. In both spring and fall at favorable elongations, we see Mercury near perihelion, that close point. Southern hemisphere observers get a better view of it. Having a late spring greatest eastern elongation we get to see Mercury farther from the Sun than the same elongation earlier in the year.

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

Addendum

Mercury in the evening

Mercury in the evening tonight at 10 pm June 3, 2020 (About 45 minutes after sunset). Click on the image to enlarge. Created using Stellarium.