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10/04/2021 – Ephemeris – Why we can’t talk to the Perseverance rover on Mars right now

October 4, 2021 Comments off

This is Ephemeris for Monday, October 4th. Today the Sun will be up for 11 hours and 32 minutes, setting at 7:17, and it will rise tomorrow at 7:46. The Moon, 2 days before new, will rise at 6:30 tomorrow morning.

NASA is no longer sending commands to its Perseverance rover or any of its assets roving or orbiting Mars now. The reason isn’t particularly sinister. It’s the approximately 26 month Mars solar conjunction. The Sun is a noisy radio source, and commands sent to or data received from these martian assets could be garbled. This affects everyone’s assets on or orbiting Mars, which includes the Europeans, India, China and the United Arab Emirates. For NASA, communication restrictions started two days ago and will last until the 14th. This will give the folks at JPL who are operating the Curiosity and Perseverance rovers some time off, and time to plan the next few months of activity.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4 hours). They may be different for your location.

Addendum

Mars in solar conjunction.

Mars in solar conjunction. Looking at the inner solar system.  Mars, near the bottom of the image, is 244.6 million miles (393.9 million kilometers) from Earth. Click on the image to enlarge it. Credit NASA’s Eyes app.

Mars beyond and to the upper left of the Sun yesterday

Mars beyond and to the upper left of the Sun yesterday. It’s tough to get intelligible radio signals through the solar corona. Credit: NASA/ESA SOHO* spacecraft. The annotation is mine.

* SOlar and Heliospheric Observatory, spacecraft in halo orbit around the Lagrangian L1 equilibrium point about  930,000 miles (1,500,000 kilometers) sunward of the Earth. This keeps the satellite roughly between the Sun and the Earth, instead of moving ahead of the Earth because it’s closer to the Sun.

07/05/2021 – Ephemeris – Happy Aphelion Day

July 5, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, July 5th. Today the Sun will be up for 15 hours and 27 minutes, setting at 9:30, and it will rise tomorrow at 6:04. The Moon, halfway from last quarter to new, will rise at 3:24 tomorrow morning.

Today, the Moon and Sun are at their farthest from the Earth. For the Moon it’s called apogee, for the Sun it’s called aphelion. At 10:48 this morning the Moon will be at that point 251,842 miles (405,300 kilometers) away. The Sun will be farthest at 10:59 pm at a distance of 94 million, 452 thousand miles (152 million, 6 thousand kilometers) away. Because of the gravitational pull of the Moon and planets on the Earth, and the Pull of the planets, especially Jupiter on the Sun, the aphelion and perihelion or closest date in January don’t occur on the same date or same distance every year. The date wanders by a day or two each year. The entire distance variation for the Earth is plus or minus 1.5 million miles (2.4 million kilometers) over the year, but makes summer the longest season by a few days because the Earth moves slower when farther from the Sun, than when it is nearer.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4). They may be different for your location.

Addendum

Earth's orbit

The Earth’s orbital ellipse, somewhat exaggerated, showing perihelion, aphelion and the seasons. Credit “Starts with a Bang” blog by Ethan Siegel.

Currently, summer is the longest season at 93.65 days, while winter is the shortest season at 88.99 days. (Source: Astronomical Tables of the Sun, Moon and Planets, Third Edition by Jean Meeus)

06/09/2021 – Ephemeris – The Sun will be partially eclipsed as it rises tomorrow morning

June 9, 2021 Comments off

I’ll review the planets tomorrow. However, tomorrow morning, if it’s clear down to the northeastern horizon, we will get to observe, safely, the Sun rise while being in eclipse. Here’s today’s program:

This is Ephemeris for Wednesday, June 9th. Today the Sun will be up for 15 hours and 30 minutes, setting at 9:27, and it will rise tomorrow at 5:57. The Moon, 1 day before new today, will rise with the Sun at 5:57 tomorrow morning.

The Moon rising with the Sun will also be eclipsing the Sun, so the Sun will have a big bite taken out of its left side as it rises tomorrow. We will be witnessing the last 40 some minutes of the eclipse as the Sun rises. The Sun is dangerous to look at. If you have eclipse glasses from the 2017 eclipse, use those. Otherwise, use pinhole projection from one side of a box to the opposite side. The longer the box, the bigger and dimmer the image. If using a corrugated cardboard box, make a big hole at the pinhole end, cover it with a thin piece of cardboard or aluminum foil. Punch several holes of various sizes spaced out on that end to project multiple images of the Sun, so you can choose the best to view. Good luck!

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

Addendum

Two pinhole solar projection methods

 Pinhole projection is the simplest way to project the Sun’s image. A long box can be used to project the image inside. The diameter of the pinhole is a compromise between sharpness and brightness of the image. The farther the image is projected, the larger and dimmer it is. The throw of the image can be increased by using a mirror masked with a quarter of an inch or larger hole and sending the image 10 or more feet away. Credit NASA.

Eclipsed Sun rising

A Stellarium creation of what the eclipsed Sun would appear about 10 minutes after rising as seen from the Traverse City/Interlochen area.

The visibility map for the June 10, 2021 annular solar eclipse

The visibility map for the June 10, 2021 annular solar eclipse. In an annular eclipse, the Moon is too far away and appears too small to cover the face of the Sun. So, at maximum, a ring of bright Sun surrounds the Moon. It’s sometimes called a ring of fire. For locations within the big floppy figure 8, the eclipse either ends near sunrise (bottom lobe) or starts near sunset (top lobe). The double line with the ellipses in it is the path of where the ring is visible, the path of annularity. Locations within the grid on the right will see a partial eclipse. Credit: NASA/GSFC/Fred Espenak, adapted from https://eclipse.gsfc.nasa.gov/SEplot/SEplot2001/SE2021Jun10A.GIF

 

06/08/2021 – Ephemeris – The Sun will be partially eclipsed as it rises Thursday

June 8, 2021 Comments off

This is Ephemeris for Tuesday, 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, 2 days before new, will rise at 5:22 tomorrow morning.

Thursday morning we in Michigan will witness the last moments of a solar eclipse as the Sun rises. The Sun will be partially eclipsed at sunrise north of a line from North Dakota to South Carolina. For those in a path that will run from the north shore of Lake Superior across western Ontario, through parts of Hudson Bay, to clipping the North Pole and into Siberia will see an annular eclipse. That is, the Moon is too far away, and small to cover the face of the Sun, leaving a bright ring or annulus. A ring of fire, some would say. For us, the Sun will rise around 5:57 am with the Moon taking a big chunk out of its left side. That chunk will recede until the Sun will appear whole again around 6:42 am. I’ll discuss how to view this eclipse tomorrow.

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

Addendum

Eclipsed Sun rising

A Stellarium creation of what the eclipsed Sun would appear about 10 minutes after rising as seen from the Traverse City/Interlochen area.

The visibility map for the June 10, 2021 annular solar eclipse

The visibility map for the June 10, 2021 annular solar eclipse. In an annular eclipse, the Moon is too far away and appears too small to cover the face of the Sun. So, at maximum, a ring of bright Sun surrounds the Moon. It’s sometimes called a ring of fire. For locations within the big red floppy figure 8, the eclipse either ends near sunrise (bottom lobe) or starts near sunset (top lobe). The double line with the ellipses in it is the path of where the ring is visible, the path of annularity. Locations within the grid on the right will see a partial eclipse. Credit: NASA/GSFC/Fred Espenak, adapted from https://eclipse.gsfc.nasa.gov/SEplot/SEplot2001/SE2021Jun10A.GIF

05/27/2021 – Ephemeris – Miss yesterday’s eclipse? There’s 2 more in the next 12 months.

May 27, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, May 27th. Today the Sun will be up for 15 hours and 13 minutes, setting at 9:17, and it will rise tomorrow at 6:02. The Moon, 1 day past full, will rise at 11:14 this evening.

While yesterday morning’s lunar eclipse may have been disappointing by setting just as it got going. That won’t happen with the next one. The next lunar eclipse visible from Northern Michigan will occur this November 19th, a Friday. It’s another morning eclipse, but doesn’t compete with sunrise or morning twilight. It’s not quite total, but nearly 97.5% of the Moon’s diameter will be covered by the Earth’s inner umbral shadow. The partial eclipse will start at 2:18 am and end at 5:47 am, which in November is nowhere near sunrise. We seem to be coming into a fortuitous period of eclipses in the next few years. Our next lunar eclipse after November will be next May 15th’s lunar eclipse, and it will be total and will conveniently happen in the evening.

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

05/25/2021 – Ephemeris – Viewing the lunar eclipse tomorrow morning

May 25, 2021 1 comment

This post is for the appearance of the May 26th lunar eclipse in Michigan.

This is Ephemeris for Tuesday, May 25th. Today the Sun will be up for 15 hours and 10 minutes, setting at 9:15, and it will rise tomorrow at 6:04. The Moon, 1 day before full, will set at 6:09 tomorrow morning.

If we are really lucky tomorrow morning, and it is clear all the way down to the southwestern horizon at dawn we will witness the start of an eclipse of the Moon near sunrise and moonset. The eclipse starts at 4:48 am, but nothing unusual will be visible as the Moon starts to enter Earth’s outer, penumbral shadow. Perhaps by 5:15 the left edge of the Moon might appear dimmer than the right side. The Moon will be getting deeper in that shadow for the next half hour until at 5:45 it begins to enter the Earth’s inner shadow, the umbra. The only light in the umbra is that bent into it by the simultaneous sunrises and sunsets around the Earth. For the next 20 to 25 minutes the shadow will increase until the Sun rises and shortly after that the Moon sets around 6:09.

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

Addendum

Moon deep in the penumbra

Simulated image of the Moon deep in the penumbra of the lunar eclipse of May 26, 2021 at 5:40 am. Notice that the left side of the Moon is darker than the right side. I find that the effect is more noticeable when wearing sunglasses to cut down the Moon’s bright glare. Created using Stellarium.

The partially eclipsed moon at moonset

Simulated view of the partially eclipsed Moon of May 26, 2021 setting on a flat horizon. Created using Stellarium and touched up by using GIMP.

Time Event
4:47 am Nautical twilight starts
4:48 am The Moon enters penumbra (Nothing to see, the dimming on the left side is imperceptible)
5:15 am The penumbral shadow should become visible at the left edge of the Moon by this time
5:45 am The Moon enters the umbra (The partial part of the eclipse begins)
6:04 am Sunrise for Traverse City
6:09 am Moon sets for Traverse City

The sunrise and moon set times may vary by more than a few minutes depending on your location.

05/24/2021 – Ephemeris – Get ready for Wednesday morning’s lunar eclipse

May 24, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, May 24th. Today the Sun will be up for 15 hours and 8 minutes, setting at 9:14, and it will rise tomorrow at 6:04. The Moon, 2 days before full, will set at 5:33 tomorrow morning.

If we are really lucky Wednesday morning, and it is clear all the way down to the southwestern horizon at dawn, we will witness the start of an eclipse of the Moon as the Sun rises and the Moon sets. The first inkling that something strange is happening to the Moon will come around 5:15 am or so. The Moon will be deep in the Earth’s outer, partial, shadow called the penumbra and the left side of the Moon should appear darker than the rest of it. The brightening of the twilight should enhance the effect. The partial phase of the eclipse will start at 5:45, where the left edge of the Moon will actually begin to disappear into the Earth’s inner shadow, the umbra. Within 20 to 25minutes later the Sun will rise and shortly after the Moon will set.

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

Addendum

Moon deep in the penumbra

Simulated image of the Moon deep in the penumbra of the lunar eclipse of May 26, 2021 at 5:40 am. Notice that the left side of the Moon is darker than the right side. I find that the effect is more noticeable when wearing sunglasses to cut down the Moon’s bright glare. Created using Stellarium.

Created with GIMP by Bob Moler

Simulated view of the partially eclipsed Moon of May 26, 2021 setting on a flat horizon. Created using Stellarium and touched up by using GIMP.

Time Event
4:47 am Nautical twilight starts
4:48 am The Moon enters penumbra (Nothing to see, the dimming on the left side is imperceptible)
5:15 am The penumbral shadow should become visible at the left edge of the Moon by this time
5:45 am The Moon enters the umbra (The partial part of the eclipse begins)
6:04 am Sunrise for Traverse City
6:09 am Moon sets for Traverse City

The sunrise and moon set times may vary by more than a few minutes depending on your location.

05/18/2021 – Ephemeris – Eclipses visible in Northern Michigan this year

May 18, 2021 Comments off

This is Ephemeris for Tuesday, May 18th. Today the Sun will be up for 14 hours and 56 minutes, setting at 9:08, and it will rise tomorrow at 6:10. The Moon, 1 day before first quarter, will set at 2:57 tomorrow morning.

This year we will see in part or in full three eclipses from our Northern Michigan location. The first will be the start of a total lunar eclipse next week Wednesday, May 26th. It will start just before sunrise, which for a full moon is around moonset. Our next eclipse will be a solar eclipse that starts, for us, before sunrise on June 10th. In fact, most of the eclipse will occur before sunrise for us in Northern Michigan. The farther north and east of us the more of the eclipse you’ll see. I’ll have more information on the lunar in the next week of programs. And the solar eclipse as we approach that date. We have a final lunar eclipse this year. That will occur in the wee morning hours of November 19th, a partial, but almost total eclipse.

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

Addendum

The four eclipses that occur in 2021

We in Northern Michigan we’ll see part of the first two and all of the third.

May 26, 2021 Total Lunar Eclipse
The visibility map for the May 26th total lunar eclipse. Note Michigan’s mitten lies between the U1 and U2, which means that the Moon will set after the partial eclipse starts, but before totality. Credit: NASA/GSFC/Fred Espenak

June 10, 2021 Annular Solar Eclipse

The visibility map for the June 10, 2021 annular solar eclipse. In an annular eclipse the Moon is too far away and appears too small to cover the face of the Sun. So, at maximum a ring of bright Sun surrounds the Moon. It’s sometimes called a ring of fire. For locations within the big floppy figure 8 the eclipse either ends near sunrise or starts near sunset. The double red line with the ellipses in it is the path of where the ring is visible. Locations within the blue grid will see a partial eclipse. Credit: NASA/GSFC/Fred Espenak.
November 19, 2021 Partial Lunar Eclipse
The visibility map for the November 19, 2021 partial eclipse. The eclipse is visible in its entirety in the morning of the 19th. This eclipse is almost total. Credit: NASA/GSFC/Fred Espenak.
December 4, 2021 Total Solar Eclipse
Visibility map for the December 4, 2021 total solar eclipse. Totality is onlt visible from the Southern Ocean and Antarctica, Credit: NASA/GSFC/Fred Espenak.

05/14/2021 – Ephemeris – Astronomy Day Star Party this Saturday

May 14, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, May 14th. Today the Sun will be up for 14 hours and 48 minutes, setting at 9:03, and it will rise tomorrow at 6:14. The Moon, 3 days past new, will set at 12:07 tomorrow morning.

Tomorrow is International Astronomy Day, to celebrate it the Sleeping Bear Dunes National Lakeshore and Grand Traverse Astronomical Society will hold a special virtual star party via the Zoom Internet app. If it’s clear, Northwestern Michigan College’s professor Jerry Dobek will be transmitting live images of celestial objects that will look pretty much like what one sees through the eyepiece of a telescope. Dr. Dobek will be using the Joseph H. Rogers 0.4 meter main telescope and commenting will be members of the Grand Traverse Astronomical Society. Featured objects will be the 4-day-old crescent Moon, the tiny and elusive planet Mercury, star clusters and galaxies. The event starts at 9 pm though best viewing won’t begin until after about 9:30. Go to www.gtastro.org for instructions and a link.

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

Addendum

While attending the virtual star party you can capture the screen imaged with Alt/Print Screen keys. Paste the image into a paint or other program. I use GIMP (Gnu Image Manipulation Program), which fits my budget… It’s free. You can save the image of play with it. What I do with it is to darken the background. It should be black.

This is globular star cluster M 3. I call it the first globular cluster of spring. It’s near the star Arcturus. This is a screen capture cropped. The capture device on the 0.4 meter telescope is the Revolution Imager R2, which is actually fairly inexpensive. It outputs a video image.

I paste this image into GIMP. I use the Levels control under the Color tab.

I move the left control under the histogram to darken the sky. The left control here is set to 119, so all brightness values less than a brightness of 119 is set to black. Click OK and export the image. I didn’t change anything else.
Resultant image. Not bad. Though, I find globular clusters look better visually than their images. That is not true of nebulae or galaxies.

03/19/2021 – Ephemeris – Enjoy this last full day of winter!

March 19, 2021 Comments off

This is Ephemeris for Friday, March 19th. Today the Sun will be up for 12 hours and 7 minutes, setting at 7:54, and it will rise tomorrow at 7:45. The Moon, 2 days before first quarter, will set at 2:23 tomorrow morning.

Spring is almost here. It will arrive at 5:37 tomorrow morning, so this is the last full day of winter, such as it was. That point in time and the point in the sky where the Sun crosses the celestial equator, the imaginary line in the sky above the Earth’s equator, heading northward is called the vernal equinox. Vernal means spring and equinox means equal night, meaning that day and night are equal, which they actually were last Tuesday. Since western civilization has spread south of the equator where the seasons are reversed, our Northern Hemisphere spring equinox is the Southern Hemisphere’s autumnal equinox, so to be understandable to both hemispheres we generally say March or September equinox instead.

Addendum

Sun's path on the equinox for TC-Interlochen

The Sun’s path through the sky on an equinox day from the Traverse City/Interlochen area in Michigan. The Sun is plotted every 15 minutes. This is a stereographic projection which compresses the sky near the zenith and enlarges the sky toward the horizon. Created using my LookingUp program.