06/22/2021 – Ephemeris – Mars is poised to cross in front of the Beehive Star Cluster tonight

This is Bob Moler with Ephemeris for Tuesday, June 22nd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 2 days before full, will set at 4:41 tomorrow morning.

Tonight, the planet Mars will be at the western edge of the Beehive star cluster. Tomorrow night, Mars will be seen against its stars. Normally, the Beehive star cluster is easily seen in binoculars. The problem is, that both the cluster and Mars will be low in the west-northwestern sky, only six to seven degrees above a sea or lake horizon near the optimal time to spot them of 11 pm. It has been 8 months since Mars was opposite the Sun in our skies, and relatively close to us. Back then it was as bright as Jupiter and relatively close to the Earth. Now, Mars is 221 million miles (356 million kilometers) and 5 times farther aw0ay, about half the distance to Jupiter. It’s tiny in telescopes and very hard to pick out of the dim twilight glow of 11 pm.

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

Mars passing in front of M44 as a GIF animation. This is difficult to spot with binoculars low in the west-northwest at 11 pm on the nights of June 22nd, 23rd and 24th. The Beehive star cluster is a relatively close and sparse cluster. On dark nights in early spring, the cluster looks like a fuzzy spot to the naked-eye. It reveals its true nature in binoculars. Created using Cartes du Ciel.

06/21/2021 – Ephemeris – A quick look at three of the naked-eye planets

This is Ephemeris for Monday, June 21st. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:57. The Moon, 3 days before full, will set at 4:02 tomorrow morning.

I have a couple of pieces of planetary news. Venus will pass south of the star Pollux in Gemini tonight. That means in their current orientation, low on the west-northwestern horizon, that Pollux will appear above and right of the much brighter Venus. This may be visible by 10:30 pm. Venus will set tonight at 11:07. You’ll need a really low western horizon to see it. In the morning sky, Saturn is backtracking to the west slowly, and now Jupiter has stopped its eastward motion and is stationary today and will start its retrograde or westward motion. Both retrograde motions are caused by the Earth, which is in the process of passing these planets. We will pass Saturn August 2nd, and pass Jupiter August 19th. We call these events, oppositions.

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

Addendum

Venus, Pollux and Mars in the evening twilight tonight at 10:30 pm. Venus and Pollux in evening twilight. Venus will be about 5 degrees above the sea or lake horizon at that time. Venus and Mars will cross their apparent paths and be in conjunction on July 13th. Click on the image to enlarge. Created using Stellarium.

Jupiter’s retrograde path, June 21, to October 20, 2021. The constellation lines in the lower right are for the eastern end of Capricornus. We pass Jupiter, officially called opposition from the Sun, on August 20th. The solid yellow line above Jupiter’s apparent path is the Ecliptic, the Sun’s apparent path in the sky. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).

06/18/2021 – Ephemeris – Summer* will start Sunday night

This is Bob Moler with Ephemeris for Friday, 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 first quarter, will set at 2:41 tomorrow morning.

Summer is just a couple of days away, though we have already been sweltering through a very hot first half of June. Summer will officially arrive for us on Earth’s Northern Hemisphere at 11: 32 pm, June 20th. If you are south of the equator, winter will arrive. If you are listening to this on the Internet, or reading this on my blog, it’s 3:32 UT, June 21st. And to be season agnostic, it’s the June solstice. From the 20th to the December solstice, the first day of winter for we northern hemispherians, (I think that’s a word) the daylight hours will get shorter as the Sun heads south. Solstice means Sun standstill as it stops its northerly motion and will, after Sunday, head back south again. The Northern Hemisphere will still be heating up for another month.

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

* Summer in the Northern Hemisphere only. Winter starts in the Southern Hemisphere.

Addendum

The Sun’s path through the sky on the summer solstice day from Traverse City, MI. The Sun is plotted every 15 minutes. The Sun’s motion is constant. The closeness of the Sun plots at higher altitudes is an artifact of portraying a hemispherical sky on a flat screen. It is a stereographic projection. Created using my LookingUp program.

Earth and magnified local area near summer solstice. Image taken near local noon June 17, 2020. Credit NOAA DSCOVR satellite orbiting the Sun-Earth L1 point 994,970 miles (1,601,432 kilometers) sunward from the Earth.

06/17/2021 – Ephemeris – Congress approves more money for NASA’s lunar lander

This is Bob Moler with Ephemeris for Thursday, June 17th. 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, at first quarter tonight, will set at 2:18 tomorrow morning. | Tonight’s Moon will be almost exactly cut in half by the sunrise terminator, since the precise moment of first quarter will be at 11:54 this evening. Speaking of the Moon, Congress has approved NASA spending of 10 billion dollars over 5 years on the Human Lander System for the Artemis Moon program. This would allow more than one bidder to win the lander contract. SpaceX’s Lunar Starship was the only one to win a contract. NASA and Congress wanted two to win, but couldn’t afford more than SpaceX. Now comes the rub… Congress will have to appropriate the money out of the budget every year for this. The target date for the first landing is 2024, which I’m pretty sure is already out of reach.

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

First Quarter Moon with binoculars or low power telescope as it might appear tonight at 11 pm. Created using Stellarium.

Three Lunar Lander proposals. Credit Dynetics, SpaceX, and Blue Origin. Credit NASA.

Technical and Management Adjectival Ratings from https://www.nasa.gov/sites/default/files/atoms/files/option-a-source-selection-statement-final.pdf

Also, SpaceX’s bid was the lowest by a wide margin. With the extra funds, it looks like Blue Origin will be the second successful bidder.

06/16/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

This is Bob Moler with Ephemeris for Wednesday, June 16th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:30, and it will rise tomorrow at 5:56. The Moon, 1 day before first quarter, will set at 1:55 tomorrow morning.

Let’s search for the naked-eye planets for this week. Venus can be spotted low in the west-northwest twilight by 10 pm or a little after. Venus will set at 11:04 pm. Mars can be found in the west-northwest at 10:30 tonight, It’s in Cancer and by next Wednesday will pass in front of the Beehive star cluster which can be easily seen in a pair of binoculars. Check it out each night before then and watch Mars approach the cluster, now to its upper left. Mars will set at 11:55 pm. Jupiter and Saturn, are in the morning sky. Saturn will rise at 12:12 am. It’s seen with the stars of Capricornus. Brighter Jupiter, to the left of Saturn, will rise at 1:01 am. By 5 am, these two planets will be in the south-southeast in the morning twilight.

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

Addendum

Venus in evening twilight at 10 pm or a half hour after sunset tonight over a sea or Lake Michigan horizon. Venus is a bit less than 10 degrees altitude. Created using Stellarium.

The Moon, Mars and Venus at 11 pm or an hour and a half after sunset tonight over a sea or Lake Michigan horizon. Click on the image to enlarge. Created using Stellarium.

Mars and the Beehive star cluster at 11 pm tonight as they might be seen in binoculars. Created using Stellarium.

The Moon as it might appear tonight in binoculars or small telescope tonight. Created using Stellarium.

Jupiter and Saturn at 5 am or an hour before sunrise tomorrow morning. Created using Stellarium.

Telescopic views of Venus, Saturn and Jupiter. Venus at the same magnification. Venus, seen at 10 pm, will be 10.72″ in diameter. Saturn at 5 am will be 18.00″ in diameter, its rings 44.43″ in extent. And Jupiter will be 43.43″. The normal cutoff for whether to show a planet here is an apparent diameter of 10″ or greater. Mars doesn’t make the cut, its apparent diameter will be 3.98″ tonight. The ” symbol means seconds of arc (1/3600th of a degree). Created using Cartes du Ciel (Sky Charts).

Planets and the Moon at sunset and sunrise of a single night, starting with sunset on the right on June 16, 2021. The night ends on the left with sunrise on the 17th. Click on the image to enlarge. Created using my LookingUp program.

 

 

06/15/2021 – Ephemeris – Today we had the earliest sunrise of the year

This is Ephemeris for Tuesday, June 15th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:30, and it will rise tomorrow at 5:56. The Moon, 2 days before first quarter, will set at 1:29 tomorrow morning.

Today is the day of the year with the earliest sunrise, which in the Interlochen/Traverse City area is 6:56 am. We are 5 days before the summer solstice, the longest day in terms of sunshine hours. With the Sun nearing its maximum angle above the celestial equator, the projection of the Earth’s equator on the sky it cuts those longitude timelines quicker because they are closer together than at the equator. This is counters somewhat the Sun’s speed slowing down as the Earth is reaching the farthest point in its orbit. The latest sunset will occur about June 26th, a span of 11 days. In December the span between the earliest sunset and latest sunrise because of the Sun’s increased speed, by being nearly at its closest to us, is 24 days.

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

Addendum

How the Sun’s declination affects how rapidly it appears to cross time lines (meridians)

These graphs show how the earth’s orbit eccentricity and tilt of the Earth’s axis (obliquity) affect sundial time keeping vs. actual clocks. This also affects sunrise and sunset times. The figure 8 in the lower right is the analemma, sometimes seen on old Earth globes, a graphical representation of the equation of time (sundial corrections from apparent to mean solar time).

Table of Earliest and Latest Sunrises and Sunsets during the year for Interlochen/Traverse City area of Michigan. This table was created for 2017, 4 years ago. However, the instant of the summer solstice occurred just after midnight on June 21st, That instant slipped back into just before midnight in 2021. This is why we use the Gregorian calendar. The slide is corrected by having 3 out of four century years being normal years.

06/14/2021 – Ephemeris – Images of the Moon: Then and now

This is Bob Moler with Ephemeris for Flag Day, Monday, June 14th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 3 days before first quarter, will set at 1 am.

The waxing crescent Moon shows its cratered highlands and flat lava plains that early telescopic astronomers fancied as water filled and called them seas, so the nomenclature stuck, and we call them seas to this day. When I grew up in the 1950s I was captivated by the moonscapes painted by Chesley Bonestell with their sharp rugged mountain peaks. The actual lunar landscape turned out to be softer, more rounded. The Earth’s surface features are younger than the Moon’s due to plate tectonics, something few geologists in the 1950s believed in. The Moon’s features are generally billions of years old and erosion by meteoroid impacts and ejecta have covered the landscape with a fine dust, over the eons, that smooths out its features.

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

Addendum

A Chesley Bonestell moonscape. Note the sharp detail including an arch at center right and an overhang at right. Such was the state of our ignorance before spacecraft like Ranger, Surveyor, Lunar Orbiter and Apollo reached the Moon. Click on the image to enlarge. Credit Chesley Bonestell.

Moonscape photographed by JAXA (Japan) spacecraft Kaguya with about the same orientation as the Bonestell painting, except from orbit. Click on the image to enlarge. Credit JAXA/NHK.

Image from Apollo 17 showing lunar erosion. Even the rocks in the foreground show that they were eroded. The image also shows astronaut Dr. Harrison “Jack” Schmidt. Click on the image to enlarge. Credit NASA.

06/11/2021 – Ephemeris – Spotting the one-day-old Moon

This is Bob Moler with Ephemeris for Friday, 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, 1 day past new, will set at 10:56 this evening.

Tonight the thin crescent Moon, some 40 hours old, or more properly 40 hours from eclipsing the Sun, will be to the right and a bit below the bright planet Venus. It might be possible to spot it. I do remember spotting the tiny sliver of a Moon the next evening after a solar eclipse in 1970. But that was in March*, when the ecliptic, the path of the Sun and near the path of all the planets and the Moon, was angled more vertically than it is this time of year. That means that the Moon and planets, when near the Sun, are lower in the sky after sunset than they would be in late winter and early spring. Venus is slowly moving away from the Sun, from our vantage point, while Mars, above and left of it, is slowly retreating toward the Sun. Their apparent paths will cross on July 13th.

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

* On the program, I mistakenly said April.

Addendum

Sunset sky and ecliptic (orange line) 45 minutes after sunset tonight, June 11, 2021. Note the low angle of the ecliptic, the apparent path of the Sun and near the path of the planets. The angle will get even lower as summer progresses. So planets close to the Sun will set shortly after the Sun. Created using Stellarium.

This is the sky one day after the March 7, 1970 eclipse and 45 minutes after sunset. Being March, note how steep the angle of the ecliptic, so planets close to the Sun are higher in the sky. Also, twilight ends quicker in March than in June.

Ephemeris Extra – Sunrise solar eclipse

The partially eclipsed Sun this morning, taken through a solar filter, so it’s redder than it actually was. Taken shortly after 6 am from Traverse City, MI West Middle School. There were quite a bit of clouds on the horizon. Credit Bob Moler.

Here is an unfiltered view taken a few minutes earlier:

Here is an unfiltered shot of the Sun bisected by a cloud. Credit Bob Moler.

06/10/2021 – Ephemeris – Let’s take a belated search for the naked-eye planets for this week

This is Ephemeris for Thursday, June 10th. Today the Sun will be up for 15 hours and 30 minutes, setting at 9:27, and it will rise tomorrow at 5:56. The Moon is new today, and won’t be visible.

Let’s take a belated look at the naked-eye planets for this week. Venus can be spotted low in the west-northwest twilight by 10 pm or a little after. Venus will set at 10:58 pm. Mars can be found in the west at 10:30 tonight, and about to leave the constellation of Gemini, the twins. Tonight it’s below and left of Gemini’s brightest star, Pollux. Mars will set at 12:10 am. Jupiter and Saturn, are in the morning sky. Saturn will rise at 12:40 am. It’s seen with the stars of Capricornus. It has begun its retrograde or westward motion caused by the fact that we are viewing it from another moving planet. Brighter Jupiter, is now in Aquarius, and will rise at 1:28 am. By 5 am, these two planets will be in the south-southeast in the morning twilight.

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

Addendum

Venus in the evening twilight at 10 pm or a half hour after sunset tonight, June 10, 2021. Created using Stellarium.

Mars in the evening with Castor and Pollux at 11 pm or about an hour and a half after sunset. Created using Stellarium.

Jupiter and Saturn at 5 am, one hour before sunrise. Created using Stellarium.

Saturn and Jupiter as seen in a small telescope at the same magnification at 5 am June 11, 2021. Apparent diameters: Saturn, 17.85″, rings, 41.58″; Jupiter, 42.60″. Mars is too far away to make out detail on its surface, except maybe a polar cap. Its apparent diameter is 4.04″. Venus’ apparent diameter is 10.55″ and will be added when it gets far enough from the Sun to be easily seen. The normal cutoff for whether to show a planet here is an apparent diameter of 10″ or greater. The ” symbol means seconds of arc (1/3600th of a degree). Note that Io is transiting the face of Jupiter. It would normally not be visible, but its shadow on Jupiter might be. Created using Cartes du Ciel (Sky Charts).

Planets and the Moon at sunset and sunrise of a single night, starting with sunset on the right on June 10, 2021. The night ends on the left with sunrise on the 11th. Click on the image to enlarge. Created using my LookingUp program.