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12/13/2019 – Ephemeris – Tonight is the first night that straddles the peak of the Geminid meteor shower

December 13, 2019 Leave a comment

Ephemeris for Friday, December 13th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:02, and it will rise tomorrow at 8:12. The Moon, 1 day past full, will rise at 6:33 this evening.

Tonight and tomorrow nights will straddle the peak of the Geminid meteor shower. It is the best meteor shower of the year and it is getting more active over the years. The Moon will interfere with all but the brightest meteors. The radiant is the point in space where the meteors seem to come from, which is near the star Castor in the constellation Gemini from which the shower gets its name. The meteors will be seen all over the sky, but they all can be traced back to the radiant. The body responsible for this meteor shower is an asteroid rather than a comet with the name 3200 Phaethon. It comes very close to the sun, So it may shed bits of itself due to heat stress. I suppose I can’t resist this: That’s how the asteroid crumbles.

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

Addendum

3200 Phaethon showing a tail

3200 Phaethon a rock comet showing a tail as it nears the Sun. Credit NASA/STEREO

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

The orbit of 3200 Phaethon

Orbit of 3200 Phaethon with the Earth and Phaethon at 10:02 p.m. December 12, 2019. (03:02 UT Dec 13) Credit TheSkyLive.com.

Geminid Orbits

Orbits of Fireballs on the night of December 13-14 as recorded by NASA’s All Sky Cameras six years ago. The preponderance of fireballs (bright meteors) are Geminids. These are published daily on Spaceweather.com. Credit: NASA and Spaceweather.com.

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

From the International Meteor Organization: Observing proposal: Geminids and Full Moon

 

12/12/2019 – Ephemeris – Previewing the Geminids this weekend

December 12, 2019 Leave a comment

Ephemeris for Thursday, December 12th. Today the Sun will be up for 8 hours and 51 minutes, setting at 5:02, and it will rise tomorrow at 8:11. The Moon, at full today, will rise at 5:38 this evening.

This upcoming weekend is the weekend of the greatest annual meteor shower of the year. They’re the Geminids. I confess to never having seen a Geminid. The reason is that it’s generally too cloudy, and for me too cold and this year is another problem, a bright Moon. In dark skies they have a 120 per hour peak, when the radiant point in Gemini is overhead. The body that was discovered to produce these meteors doesn’t appear to be a comet. It is designated as an asteroid 3200 Phaethon. Phaethon gets extremely close to the sun at 13 million miles (21 million km) and one of the STEREO Sun monitoring satellites caught it developing a tail when close to the Sun. Phaethon may then be the first known rock comet. I’ll have more on it tomorrow. (12/08/2014)

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

Addendum

Eastern sky for Geminids

Eastern sky for Geminids at 10 p.m. December 13, 2019. On the 14th the Moon will be the same distance from Pollux but below it. Remember that the Geminid meteors will be seen all over the sky. It might help to hide the moon behind a building so as to better see the brighter meteors. Created using Stellarium.

Geminid Orbits

Orbits of Fireballs on the night of December 13-14 as recorded by NASA’s All Sky Cameras six years ago. The preponderance of fireballs in yellow (bright meteors) are Geminids. These are published daily on Spaceweather.com. Credit: NASA and Spaceweather.com

12/11/2019 – Ephemeris – Where are the naked-eye planets now

December 11, 2019 Leave a comment

Ephemeris for Wednesday, December 11th. Today the Sun will be up for 8 hours and 52 minutes, setting at 5:02, and it will rise tomorrow at 8:10. The Moon, 1 day before full, will set at 8:28 tomorrow morning.

Let’s look at the naked-eye planets for this week. Venus will be briefly visible low in the southwest before it sets at 7:06 p.m. Jupiter is lost in twilight. It will pass behind the Sun on the 27th and will enter the morning sky. Saturn, the ringed planet, will be in the southwestern sky in the evening, and will set at 7:13 p.m. Tonight Saturn will be about 2 degrees or 4 moon widths to the upper right of the much brighter Venus. Mars is in the morning sky and will rise in the east-southeast at 5:13 a.m. It’s not very bright because it’s 215 million (346 million km) miles away, but it’s getting slowly closer to the Earth. Mercury is now too close to the Sun to be seen in morning twilight.

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

Addendum

Venus and Saturn

Venus and Saturn low ion the southwest tonight at 6 p.m. December11, 2019. Click on the image to enlarge. Created using Stellarium.

Telescopic planets

Telescopic views of Venus and Saturn with the same magnification at 6 p.m. tonight December 11, 2019. In the morning, I will show Mars here when it reaches an apparent diameter of 10″ (seconds of arc). It’s currently 4.0″. By the way Venus is 11.8″. Created using Cartes du Ciel (Sky Charts).

Binocular Moon

The nearly full Moon at 6 p.m. tonight December 11, 2019. Created using Stellarium.

Mars in the morning with the bright stars at 7 a.m. December 12, 2019. Mercury is on the horizon and most likely invisible. Click on the image to enlarge. Created using Stellarium.

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 December 11, 2019. The night ends on the left with sunrise on the 12th. Click on the image to enlarge. Created using my LookingUp program.

12/10/2019 – Ephemeris – The Moon’s natural resource more precious than gold

December 10, 2019 Comments off

Ephemeris for Tuesday, December 10th. Today the Sun will be up for 8 hours and 53 minutes, setting at 5:02 the earliest sunset, and it will rise tomorrow at 8:09. The Moon, 2 days before full, will set at 7:22 tomorrow morning.

The Moon is attracting the attention of NASA and the Chinese for crewed landings. The attraction is a natural resource the Moon has. It’s water, or rather ice. There are known water reserves in the Moon’s south polar craters, whose floors never see sunlight. That means they’re very cold. Cold traps they’re called. The Moon has a very little axial tilt so the crater floors are forever cold. They would collect water vapor from passing and colliding comets over the millennia. 10 years ago the second stage of the rocket that placed the Lunar Reconnaissance Orbiter in lunar orbit was crashed into one of the south polar craters followed by a satellite to analyze the ejecta. Water vapor was kicked up by the impact in Cabeus crater.

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

Addendum

South pole ice

The south pole of the Moon where the presence of water ice is detected by the absorption of neutrons by the hydrogen atoms in the ice. Credit NASA/GSFC/SVS/Roscosmos.

You’ll notice that the craters on the the Moon’s south pole are named for Antarctic explorers.  Besides water other volatiles were found: methane, ammonia, hydrogen gas, carbon dioxide and carbon monoxide.

Categories: Ephemeris Program, NASA Tags: ,

12/09/2019 – Ephemeris – Tomorrow is the earliest sunset

December 9, 2019 Comments off

Ephemeris for Monday, December 9th. Today the Sun will be up for 8 hours and 54 minutes, setting at 5:02, and it will rise tomorrow at 8:08. The Moon, 3 days before full, will set at 6:15 tomorrow morning.

In twelve days we will have the shortest day in terms of daylight hours. But the change isn’t uniformly distributed in the morning and evening. Tonight we will have the earliest sunset. Sunset times have been within the same minute for the last few days and will continue for the next few. The latest sunrise will occur on January second. The reason is that the Sun is traveling faster eastward than average because the Earth is closer to it now, so the Earth’s rotation takes a little longer each day to catch up with it. Near the solstice the Sun is at a higher latitude, where the longitude lines are closer together so it crosses them faster. A smaller effect exists in June because the Sun is farther away and its slowness subtracts from the higher latitude effects.

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

Addendum

Analemma

This figure 8 is called an analemma. One can find it on old globes in the Pacific Ocean. Explanation below. Created using my LookingUp program.

The Analemma

An Analemma graphically demonstrating the actual Sun’s relation to the mean Sun during the year.

From my December 2nd 2014 post with updates:

The analemma is a graphical representation of a daily value called the Equation of Time. It’s best known use is in corrections to sundial time. The vertical axis is the sun’s declination or north-south position. It is highest at summer solstice and lowest at winter solstice. It is the result of two effects: the tilt of the Earth’s axis to the plane of the Earth’s orbit around the Sun, and the change in the Earth’s velocity around the Sun as the Earth moves from perihelion, its closest to the Sun in early January to aphelion, its most distant in July.

If the Earth’s orbit were circular, and it orbited the Sun at the same speed. The analemma would be skinnier and the north and south lobes would be of equal size. Since we’re closer to the Sun in the winter, we move faster than average around the Sun, so it appears to move faster eastward. That combines with the faster appearing movement of the sun crossing the closer hour lines at higher and lower declinations (latitudes). In the diagram above note that the vertical hour lines are slightly closer together at the bottom and the top, so the Sun, moving eastward each day crosses them quicker. Near the winter solstice the two effects work together making sunrise and sunset trending to be later than normal. For the summer solstice the eastward speed of the sun is slower than normal, because we’re farther from the Sun. This works against the effect of the earth’s tilt but cannot completely negate it, making the top of the loop smaller than the one at the bottom. The arrows show the speed and direction of the Sun at the solstices.

In my month preview posts I generally mention the time of local noon for mid month.  I didn’t do it for this month. If the equation of time is zero our local solar noon, in the Interlochen/Traverse City area, the Sun is due south at 12:43 p.m. during Eastern Standard Time, because that time meridian of 75 degrees longitude runs through Philadelphia PA.  During daylight time it’s 60 degrees longitude, which clips the eastern edge of Nova Scotia.  On the top figure of the analemma, if the Sun is west of center, the Sun is fast and to the east is slow.  It changes rapidly in December, at the bottom end of the figure 8 when the Sun is farthest south.  Local solar noon on the first is at 12:31 p.m., and it will slow to 12:45 p.m. on the 31st.

To see real analemmas in the sky search for analemma images on the Internet. It takes a year to photograph one.

 

12/06/2019 – Ephemeris – I’m giving a talk tonight: Cosmology and Astronomy in the Bible

December 6, 2019 Comments off

Ephemeris for Friday, December 6th. Today the Sun will be up for 8 hours and 57 minutes, setting at 5:02, and it will rise tomorrow at 8:06. The Moon, 2 days past first quarter, will set at 3:02 tomorrow morning.

This evening yours truly will present one of his annual Christmas programs at Northwestern Michigan College’s Rogers Observatory starting at 8 p.m., the monthly meeting of the Grand Traverse Astronomical Society. The talk is Cosmology and Astronomy in the Bible. In Genesis and elsewhere we have descriptions of the earth and the heavens. We’ll look at what the ancient Hebrews thought of the structure of the universe from the Bible and other writings. Tomorrow evening we will also have a Star Party from 9 to 11 p.m. This will be the last viewing night of the year. If it’s clear we’ll look at the Moon and Great Orion Nebula. The observatory is located south of Traverse City on Birmley Road between Garfield and Keystone roads.

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

Addendum

Slide from the program

Let there be light slide from the program

12/05/2019 – Ephemeris – Artemis the new Moon program

December 5, 2019 Comments off

Ephemeris for Thursday, December 5th. Today the Sun will be up for 8 hours and 58 minutes, setting at 5:02, and it will rise tomorrow at 8:05. The Moon, 1 day past first quarter, will set at 2:01 tomorrow morning. | NASA has a new program to return to the Moon, perhaps to stay. The program is called Artemis, named after the Greek god Apollo’s twin sister. NASA is building a massive rocket called the Space Launch System, or SLS, and the Orion

, which I’m sure will guarantee European astronauts a ride. This is not going to be an Apollo type one rocket up and back. There will be a space station called the Lunar Gateway of International partners that will orbit the Moon. There the crew of the Orion Spacecraft will transfer to a Lunar Lander for the trip to and from the surface of the Moon. It’s a heavy push to accomplish by 2024.

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

Addendum

The Block 1b vrsion of the Space Launch System (SLS) which uses elongated Space Shuttle boosters and a core stage with 4 Space Shuttle main engines for the first stage. Credit NASA.

Orion MPC

Cone-shaped Orion Multi-Purpose Crew Vehicle with a European Service Module. Credit NASA.

Lunar Gateway

Lunar Gateway supplied by the same partners that built the International Space Station. It will orbit the Moon, Credit NASA.

Lunar Lander

Lunar Lander. This vehicle has not been designed yet. This is Blue Origin’s Ascent Module on top of a yet to be designed propulsion module. Credit Blue Origin.