Total Lunar Eclipse 2022 #1

The first of two total lunar eclipses this year visible from Tucson will occur conveniently this Sunday evening, May 15 (16 May 2022 UT).

Here are the local circumstances for Tucson, Arizona.

Time (MST)EventAltitude
7:06 p.m.Moonrise
7:28 p.m.Partial Eclipse Begins
8:29 p.m.Total Eclipse Begins14°
9:12 p.m.Greatest Eclipse21°
9:54 p.m.Total Eclipse Ends26°
10:56 p.m.Partial Eclipse Ends33°
11:30 p.m.Penumbra last visible?35°
11:51 p.m.Penumbral Eclipse Ends36°

There are few astronomical events as impressive as a total lunar eclipse, and we’ll have a front-row seat Sunday evening.

Every month, the full moon passes close to the Earth’s shadow, but because of the Moon’s tilted orbit it usually passes above or below the shadow cone of the Earth. This month is different!

Sunday evening, the Moon orbits right through the Earth’s shadow. At 6:32 p.m., the Moon dips his proverbial toe into the Earth’s shadow, when the Moon is still 7˚ below Tucson’s ESE horizon. This is the undetectable beginning of the eclipse, when the leading edge of the eastward orbiting-Moon “sees” a partial solar eclipse. When no part of the Moon sees anything more than the Earth blocking some but not all of the Sun, we call that a penumbral eclipse. The very subtle penumbral shading may just begin to be detectable around 7:00 p.m., but here in Tucson the Moon won’t even rise until six minutes after that.

When the partial eclipse begins at 7:28 p.m., the lower left edge becomes the first part of the Moon to “see” a total solar eclipse. In other words, from part of the Moon now, the Earth totally eclipses the Sun.

Totality begins at 8:29 p.m. when all of the Moon sees the Earth completely blocking the Sun. Mid-totality occurs at 9:12 p.m., when the center of the Moon is closest to the center of the Earth’s shadow. At that moment, the Moon’s color should be darkest.

That color is caused by sunlight refracting (bending) through the Earth’s atmosphere and shining on the Moon even though from the Moon the Earth is completely blocking the disk of the Sun. The reddish or orangish color imparted to the Moon during totality is the combined light of all the world’s sunrises and sunsets. What a beautiful thought! Had the Earth no atmosphere, the Moon would utterly disappear from view during totality—the time it is completely within the Earth’s umbral shadow.

Totality ends at 9:54 p.m., and the partial eclipse ends at 10:56 p.m. As the last vestiges of partial solar eclipse leave the Moon, the (penumbral) eclipse ends at 11:51 p.m.

This leisurely event can be enjoyed with the unaided eye, binoculars, a telescope, or all three. Don’t let anyone in the family miss seeing it!

Emergence

Physics is the fundamental science in that it describes the workings of the universe at all scales.  No other science is so comprehensive.

Will our knowledge of physics finally lead us to a “Theory of Everything”?  Perhaps, but the Theory of Everything alone will not be able to describe, predict, or explain its full expression upon/within the universe—no more so than our musical notation system can explain how a Brahms symphony was composed, nor its effect upon the listener.

Reductionism states that the whole is the sum of its parts, but emergence states that the whole is more than the sum of its parts.

There are many examples of emergent properties in the natural world, what one might call radical novelty.  Some examples:  crystal structure (e.g. a salt crystal or a snowflake), ripples in a sand dune, clouds, life itself.  Social organization (e.g. a school of fish or a city), consciousness.

John Archibald Wheeler (1911-2008) created a diagram that nicely illustrates an emergent property of the universe that is important to us.

The universe viewed as a self-excited circuit. Starting simply (thin U at right), the universe grows in complexity with time (thick U at left), eventually giving rise to observer-participancy, which in turn imparts “tangible reality” to even the earliest days of the universe.

Richard Wolfson writes,

At some level of complexity, emergent properties become so interesting that, although we understand that they come from particles that are held together by the laws of physics, we can’t understand or appreciate them through physics alone.

I like to think of emergence as an expression of creativity. Our universe is inherently creative, just as we humans express ourselves creatively through music, art, literature, architecture, and in so many other ways.

Creativity is the most natural process in the universe. It’s in our DNA.

But DNA alone can’t explain it.

References

Richard Wolfson, The Great Courses, Course No. 1280, “Physics and Our Universe: How It All Works”, Lecture 1: “The Fundamental Science”, 2011.


“And the end of all our exploring will be to arrive where we started and know the place for the first time.” – T. S. Eliot

Ending Spring Forward, Fall Back

On March 15, the U.S. Senate voted unanimously to end the twice annual switch between Standard Time and Daylight Saving Time. So far so good. That leaves us now with two choices: standard time year round or daylight saving time year round. Unfortunately, they have chosen the latter. The fact that there was no debate on this point suggests the esteemed senators collectively have little understanding of science—or, at least, biology and astronomy.

Most astronomers (those that actually observe) and astronomy educators don’t like daylight saving time because it delays the onset of darkness by an hour: most of us observe in the evening and not right before dawn. Cruelly, daylight saving time prevents many young people from experiencing the wonders of the night sky because it gets dark around or after their bedtime during the warmer months of the year.

Non-astronomers (which, let’s face it, includes most of us) that rise early in the morning will spend even more of their year getting up while it is still dark out. In the northern U.S. at least that means that during the winter months, many school children will be going to school in the dark when it is still bitterly cold.

I have written previously on this topic.

As for biology, unless all of us also start our work days and school days an hour later, year-round daylight saving time will further mess with our already-damaged circadian rhythms—and most of us don’t get enough sleep as it is. As many studies have shown, this leads to a number of negative consequences affecting our health and well being.

The answer is, of course, to adopt standard time year-round as Arizona currently does. Even that is now in jeopardy as Arizona is likely to join the bandwagon and go to permanent daylight saving time, if this legislation is enacted.

This legislation now goes to the U.S. House of Representatives and, if it passes there, on to President Biden’s desk to sign into law. If that happens, most/all? of the U.S. will be going to permanent daylight saving time beginning officially November 5, 2023 (actually, March 12, 2023).

Is anyone pushing for year-round standard time instead? You bet.

I encourage you to support this organization, Save Standard Time, a registered 501(c)(4) nonprofit organization.

February is Short, the Moon Makes Haste…

Each night for the next several nights, the Moon sets much later than it did the previous night. This happens for two reasons.

First, this week the plane of the Moon’s orbit is nearly perpendicular to our horizon, so much of the Moon’s orbital motion eastward relative to the background stars (if we could see them) during the day takes it directly away from the western horizon, thus slowing as much as possible its inexorable march towards the west caused by the Earth’s rotation.

Second, this week the Moon is moving north in declination, and this, too, increases the amount of time the Moon stays above the horizon. The closer to the north celestial pole an object is, the longer it stays above our horizon, the further north along the western horizon it sets, and the later it sets. The Moon’s motion during the day northward relative to the celestial equator causes the Moon to set further north than it would have otherwise. The combination of these two factors makes moonset much later each night, as shown in the table below.

But, why doesn’t moonrise also occur much later each morning? As you can see by inspecting the table above, the Moon rises only a little later each day, in marked contrast to the leaps and bounds moonset is later each night. The factors are the same, but the effect is different. Because the Moon is moving north and is thus rising further north every morning, it rises earlier than it would have otherwise. Although the Moon is rising later each day due to its eastward orbital motion, moonrise is only a little later due to the countereffect of an earlier rise time stemming from the Moon’s more northerly declination.

It is no wonder humans have always been fascinated by the Moon’s complex motion. Throughout history, a number of mathematicians have taken up the challenge of trying to understand and predict the Moon’s motion, leading to several important advancements in mathematics.

Zodiacal Light 2022

In 2022, the best dates and times for observing the zodiacal light are listed in the calendar below. The sky must be very clear with little or no light pollution. The specific times listed are for Dodgeville, Wisconsin (42° 58′ N, 90° 08′ W).

Here’s a nicely-formatted printable PDF file of the zodiacal light calendar:

January 2022
SUN MON TUE WED THU FRI SAT
            1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19
Zodiacal Light 6:36 – 6:38 p.m. West
20
Zodiacal Light 6:37 – 7:37 p.m. West
21
Zodiacal Light 6:38 – 7:38 p.m. West
22
Zodiacal Light 6:39 – 7:39 p.m. West
23
Zodiacal Light 6:40 – 7:40 p.m. West
24
Zodiacal Light 6:41 – 7:41 p.m. West
25
Zodiacal Light 6:42 – 7:42 p.m. West
26
Zodiacal Light 6:43 – 7:43 p.m. West
27
Zodiacal Light 6:44 – 7:44 p.m. West
28
Zodiacal Light 6:46 – 7:46 p.m. West
29
Zodiacal Light 6:47 – 7:47 p.m. West
30
Zodiacal Light 6:48 – 7:48 p.m. West
31
Zodiacal Light 6:49 – 7:49 p.m. West
         

February 2022
SUN MON TUE WED THU FRI SAT
    1
Zodiacal Light 6:50 – 7:50 p.m. West
2
Zodiacal Light 7:04 – 7:51 p.m. West
3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18
Zodiacal Light 7:10 – 7:51 p.m. West
19
Zodiacal Light 7:12 – 8:12 p.m. West
20
Zodiacal Light 7:13 – 8:13 p.m. West
21
Zodiacal Light 7:14 – 8:14 p.m. West
22
Zodiacal Light 7:15 – 8:15 p.m. West
23
Zodiacal Light 7:16 – 8:16 p.m. West
24
Zodiacal Light 7:18 – 8:18 p.m. West
25
Zodiacal Light 7:19 – 8:19 p.m. West
26
Zodiacal Light 7:20 – 8:20 p.m. West
27
Zodiacal Light 7:21 – 8:21 p.m. West
28
Zodiacal Light 7:22 – 8:22 p.m. West
         

March 2022
SUN MON TUE WED THU FRI SAT
    1
Zodiacal Light 7:24 – 8:24 p.m. West
2
Zodiacal Light 7:25 – 8:25 p.m. West
3
Zodiacal Light 7:26 – 8:26 p.m. West
4
Zodiacal Light 8:14 – 8:27 p.m. West
5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
Zodiacal Light 8:47 – 8:59 p.m. West
20
Zodiacal Light 8:48 – 9:48 p.m. West
21
Zodiacal Light 8:49 – 9:49 p.m. West
22
Zodiacal Light 8:51 – 9:51 p.m. West
23
Zodiacal Light 8:52 – 9:52 p.m. West
24
Zodiacal Light 8:53 – 9:53 p.m. West
25
Zodiacal Light 8:55 – 9:55 p.m. West
26
Zodiacal Light 8:56 – 9:56 p.m. West
27
Zodiacal Light 8:57 – 9:57 p.m. West
28
Zodiacal Light 8:59 – 9:59 p.m. West
29
Zodiacal Light 9:00 – 10:00 p.m. West
30
Zodiacal Light 9:02 – 10:02 p.m. West
31
Zodiacal Light 9:03 – 10:03 p.m. West
   

April 2022
SUN MON TUE WED THU FRI SAT
          1
Zodiacal Light 9:05 – 10:05 p.m. West
2
Zodiacal Light 9:11 – 10:06 p.m. West
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

May 2022
SUN MON TUE WED THU FRI SAT
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31        

June 2022
SUN MON TUE WED THU FRI SAT
      1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30    

July 2022
SUN MON TUE WED THU FRI SAT
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31            

August 2022
SUN MON TUE WED THU FRI SAT
  1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25
Zodiacal Light 3:33 – 4:11 a.m. East
26
Zodiacal Light 3:35 – 4:35 a.m. East
27
Zodiacal Light 3:36 – 4:36 a.m. East
28
Zodiacal Light 3:38 – 4:38 a.m. East
29
Zodiacal Light 3:39 – 4:39 a.m. East
30
Zodiacal Light 3:41 – 4:41 a.m. East
31
Zodiacal Light 3:42 – 4:42 a.m. East
     

September 2022
SUN MON TUE WED THU FRI SAT
        1
Zodiacal Light 3:44 – 4:44 a.m. East
2
Zodiacal Light 3:45 – 4:45 a.m. East
3
Zodiacal Light 3:47 – 4:47 a.m. East
4
Zodiacal Light 3:48 – 4:48 a.m. East
5
Zodiacal Light 3:49 – 4:49 a.m. East
6
Zodiacal Light 3:51 – 4:51 a.m. East
7
Zodiacal Light 3:52 – 4:52 a.m. East
8
Zodiacal Light 3:57 – 4:54 a.m. East
9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
Zodiacal Light 4:14 – 5:14 a.m. East
25
Zodiacal Light 4:16 – 5:16 a.m. East
26
Zodiacal Light 4:17 – 5:17 a.m. East
27
Zodiacal Light 4:18 – 5:18 a.m. East
28
Zodiacal Light 4:19 – 5:19 a.m. East
29
Zodiacal Light 4:21 – 5:21 a.m. East
30
Zodiacal Light 4:22 – 5:22 a.m. East
 

October 2022
SUN MON TUE WED THU FRI SAT
            1
Zodiacal Light 4:23 – 5:23 a.m. East
2
Zodiacal Light 4:24 – 5:24 a.m. East
3
Zodiacal Light 4:25 – 5:25 a.m. East
4
Zodiacal Light 4:27 – 5:27 a.m. East
5
Zodiacal Light 4:28 – 5:28 a.m. East
6
Zodiacal Light 4:29 – 5:29 a.m. East
7
Zodiacal Light 4:30 – 5:30 a.m. East
8
Zodiacal Light 5:28 – 5:31 a.m. East
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23
Zodiacal Light 4:48 – 5:12 a.m. East
24
Zodiacal Light 4:50 – 5:50 a.m. East
25
Zodiacal Light 4:51 – 5:51 a.m. East
26
Zodiacal Light 4:52 – 5:52 a.m. East
27
Zodiacal Light 4:53 – 5:53 a.m. East
28
Zodiacal Light 4:54 – 5:54 a.m. East
29
Zodiacal Light 4:55 – 5:55 a.m. East
30
Zodiacal Light 4:56 – 5:56 a.m. East
31
Zodiacal Light 4:57 – 5:57 a.m. East
         

November 2022
SUN MON TUE WED THU FRI SAT
    1
Zodiacal Light 4:59 – 5:59 a.m. East
2
Zodiacal Light 5:00 – 6:00 a.m. East
3
Zodiacal Light 5:01 – 6:01 a.m. East
4
Zodiacal Light 5:02 – 6:02 a.m. East
5
Zodiacal Light 5:03 – 6:03 a.m. East
6
Zodiacal Light 4:35 – 5:04 a.m. East
7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22
Zodiacal Light 4:21 – 5:21 a.m. East
23
Zodiacal Light 4:22 – 5:22 a.m. East
24
Zodiacal Light 4:23 – 5:23 a.m. East
25
Zodiacal Light 4:24 – 5:24 a.m. East
26
Zodiacal Light 4:25 – 5:25 a.m. East
27
Zodiacal Light 4:26 – 5:26 a.m. East
28
Zodiacal Light 4:27 – 5:27 a.m. East
29
Zodiacal Light 4:28 – 5:28 a.m. East
30
Zodiacal Light 4:29 – 5:29 a.m. East
     

December 2022
SUN MON TUE WED THU FRI SAT
        1
Zodiacal Light 4:30 – 5:30 a.m. East
2
Zodiacal Light 4:31 – 5:31 a.m. East
3
Zodiacal Light 4:32 – 5:32 a.m. East
4
Zodiacal Light 4:33 – 5:33 a.m. East
5
Zodiacal Light 4:41 – 5:34 a.m. East
6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

The best nights to observe the zodiacal light at mid-northern latitudes occur when the ecliptic plane intersects the horizon at an angle of 60° or steeper. The dates above were chosen on that basis, with the Sun at least 18° below the horizon and the Moon below the horizon being used to calculate the times. An interval of time of one hour either before morning twilight or after evening twilight was chosen arbitrarily because it is the “best one hour” for observing the zodiacal light. The zodiacal light cone will be brightest and will reach highest above the horizon when the Sun is 18° below the horizon (astronomical twilight), but no less.

If you are interested in calculating the angle the ecliptic makes with your horizon for any date and time, you can use the following formula:

\cos I = \cos \varepsilon \sin \phi-\sin \varepsilon \cos \phi \sin \theta

where I is the angle between the ecliptic and the horizon, ε is  the obliquity of the ecliptic, φ is the latitude of the observer, and θ is the local sidereal time (the right ascension of objects on the observer's meridian at the time of observation).

Here’s a SAS program I wrote to do these calculations:

References
Meeus, J. Astronomical Algorithms. 2nd ed., Willmann-Bell, 1998, p. 99.

Meteor Shower Calendar 2022

Here’s our meteor shower calendar for 2022.  It is sourced from the IMO’s Working List of Visual Meteor Showers (https://www.imo.net/files/meteor-shower/cal2022.pdf, Table 5, p. 25).

Each meteor shower is identified using its three-character IAU meteor shower code.  Codes are bold on the date of maximum, and one day either side of maximum.

Some additional events have been added to the calendar from Sources of Possible or Additional Activity, Table 6a, p. 27). I used the following abbreviations for the Table 6a events that do not have a standard three-character meteor code:

GY2 = 2006 GY2
209 = 209P/LINEAR
CK1 = C/1852 K1

Here’s a printable PDF file of the meteor shower calendar shown below:

Happy meteor watching!

January 2022
SUN MON TUE WED THU FRI SAT
            1
DLM QUA
2
DLM QUA
3
DLM QUA
4
DLM QUA
5
DLM QUA
6
DLM QUA
7
DLM QUA
8
DLM QUA
9
DLM QUA KCA
10
DLM QUA GUM KCA
11
DLM QUA GUM KCA
12
DLM QUA GUM
13
DLM GUM
14
DLM GUM
15
DLM GUM
16
DLM GUM
17
DLM GUM
18
DLM GUM
19
DLM GUM
20
DLM GUM
21
DLM GUM
22
DLM GUM
23
DLM
24
DLM
25
DLM
26
DLM
27
DLM
28
DLM
29
DLM
30
DLM
31
DLM ACE
         
February 2022
SUN MON TUE WED THU FRI SAT
    1
DLM ACE
2
DLM ACE
3
DLM ACE
4
DLM ACE
5
ACE
6
ACE
7
ACE
8
ACE
9
ACE
10
ACE
11
ACE
12
ACE
13
ACE
14
ACE
15
ACE
16
ACE
17
ACE
18
ACE
19
ACE
20
ACE
21 22 23 24 25
GNO
26
GNO
27
GNO
28
GNO
         
March 2022
SUN MON TUE WED THU FRI SAT
    1
GNO
2
GNO
3
GNO
4
GNO
5
GNO
6
GNO
7
GNO
8
GNO
9
GNO
10
GNO
11
GNO
12
GNO
13
GNO
14
GNO
15
GNO
16
GNO
17
GNO
18
GNO
19
GNO
20
GNO
21
GNO
22
GNO
23
GNO
24
GNO
25
GNO
26
GNO
27
GNO
28
GNO
29 30 31    
April 2022
SUN MON TUE WED THU FRI SAT
          1 2
3 4 5 6 7 8 9
10 11 12 13 14
LYR
15
PPU LYR
16
PPU LYR
17
PPU LYR
18
PPU LYR
19
ETA PPU LYR
20
ETA PPU LYR
21
ETA PPU LYR
22
ETA PPU LYR
23
ETA PPU LYR
24
ETA PPU LYR
25
ETA PPU LYR
26
ETA PPU LYR
27
ETA PPU LYR
28
ETA PPU LYR
29
ETA LYR
30
ETA LYR
May 2022
SUN MON TUE WED THU FRI SAT
1
ETA
2
ETA
3
ELY ETA
4
ELY ETA
5
ELY ETA
6
ELY ETA
7
ELY ETA
8
ELY ETA
9
ELY ETA
10
ELY ETA
11
ELY ETA
12
ELY ETA
13
ELY ETA
14
GY2 ARI ELY ETA
15
GY2 ARI ETA
16
GY2 ARI ETA
17
ARI ETA
18
ARI ETA
19
ARI ETA
20
ARI ETA
21
ARI ETA
22
ARI ETA
23
ARI ETA
24
209 ARI ETA
25
209 ARI ETA
26
209 ARI ETA
27
ARI ETA
28
ARI ETA
29
ARI
30
TAH ARI
31
TAH ARI
       
June 2022
SUN MON TUE WED THU FRI SAT
      1
TAH ARI
2
ARI
3
ARI
4
ARI
5
ARI
6
ARI
7
ARI
8
ARI
9
ARI
10
ARI
11
ARI
12
ARI
13
ARI
14
ARI
15
ARI
16
ARI
17
ARI
18
ARI
19
ARI
20
ARI
21
ARI
22
JBO ARI
23
JBO ARI
24
JBO ARI
25
JBO
26
JBO
27
JBO
28
JBO
29
JBO
30
JBO
   
July 2022
SUN MON TUE WED THU FRI SAT
          1
JBO
2
JBO
3
CAP
4
CAP JPE
5
CAP JPE
6
CAP JPE
7
CAP JPE
8
CAP JPE
9
CAP JPE
10
CAP JPE
11
CAP JPE
12
CAP SDA JPE
13
CAP SDA JPE
14
CAP SDA JPE
15
CAP SDA PAU
16
CAP SDA PAU
17
PER CAP SDA PAU
18
PER CAP SDA PAU
19
PER CAP SDA PAU
20
PER CAP SDA PAU
21
PER CAP SDA PAU
22
PER CAP SDA PAU
23
PER CAP SDA PAU
24
PER CAP SDA PAU
25
PER CAP SDA GDR PAU
26
PER CAP SDA GDR PAU
27
PER CAP SDA GDR PAU
28
PER CAP SDA GDR PAU
29
PER CAP SDA GDR
30
PER CAP SDA GDR PAU
31
PER CAP SDA GDR PAU
           
August 2022
SUN MON TUE WED THU FRI SAT
  1
PER CAP SDA PAU
2
PER CAP SDA PAU
3
KCG PER CAP SDA PAU
4
KCG PER CAP SDA PAU
5
KCG PER CAP SDA PAU
6
KCG PER CAP SDA PAU
7
KCG PER CAP SDA PAU
8
KCG PER CAP SDA PAU
9
KCG PER CAP SDA PAU
10
KCG PER CAP SDA PAU
11
KCG PER CK1 CAP SDA
12
KCG PER CK1 CAP SDA
13
KCG PER CK1 CAP SDA
14
KCG PER CAP SDA
15
KCG PER CAP SDA
16
KCG PER SDA
17
KCG PER SDA
18
KCG PER SDA
19
KCG PER SDA
20
KCG PER SDA
21
KCG PER SDA
22
KCG PER SDA
23
KCG PER SDA
24
KCG PER
25
KCG
26 27
28
AUR
29
AUR
30
AUR
31
AUR
     
September 2022
SUN MON TUE WED THU FRI SAT
        1
AUR
2
AUR
3
AUR
4
AUR
5
SPE AUR
6
SPE
7
SPE
8
SPE
9
DSX SPE
10
STA DSX SPE
11
STA DSX SPE
12
STA DSX SPE
13
STA DSX SPE
14
STA DSX SPE
15
STA DSX SPE
16
STA DSX SPE
17
STA DSX SPE
18
STA DSX SPE
19
STA DSX SPE
20
STA DSX SPE
21
STA DSX SPE
22
STA DSX
23
STA DSX
24
STA DSX
25
STA DSX
26
STA DSX
27
STA DSX
28
STA DSX
29
STA DSX
30
STA DSX
 
October 2022
SUN MON TUE WED THU FRI SAT
            1
STA DSX
2
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Globulars Galore

So far, a total of 162 globular clusters have been discovered in our Milky Way galaxy.

Many of the recent globulars that have been discovered are either heavily obscured by intervening interstellar matter at visible wavelengths (and thus detectable only in the infrared), or they are so diffuse that they are difficult to detect against the field stars.

Here’s a list of the 88 constellations, and how many globulars have been found in each.

Milky Way Globular Clusters

46 of the 88 constellations harbor globulars (52%). Sagittarius contains the most globular clusters, 36, representing nearly 22% or about 1/5 of the total. This is perhaps not surprising as the center of our Milky Way galaxy (Sgr A*) is located at a distance of 26,673 ± 72 ly from our Solar System in the direction of Sagittarius near the Sagittarius-Ophiuchus-Scorpius border.

Only two other constellations host more than 5 globular clusters: Ophiuchus is in 2nd place with 25, and Scorpius comes in 3rd with 20. Together these three adjacent constellations, Sagittarius, Ophiuchus, and Scorpius, contain a total of 81 globular clusters, exactly half (50%) of all the known Milky Way globulars! Truly, then, the Sagittarius+Ophiuchus+Scorpius region can be called the “Realm of the Globulars”.

The northernmost globular cluster is Palomar 1 (Cepheus, α2000 = 3h33m19s, δ2000 = +79°34’55”), and the southernmost globular cluster is IC 4499 (Apus, α2000 = 15h00m19s, δ2000 = -82°12’50”).

Apus
NGC 6101
IC 4499

Aquarius
NGC 6981 (M72)
NGC 7089 (M2)
NGC 7492

Aquila
NGC 6749
NGC 6760
Palomar 11

Ara
NGC 6352
NGC 6362
NGC 6397
ESO-SC06
FSR 1735

Auriga
Palomar 2

Boötes
NGC 5466

Canes Venatici
NGC 5272 (M3)

Capricornus
NGC 7099 (M30)
Palomar 12

Carina
NGC 2808

Centaurus
NGC 5139 (Omega Centauri)
NGC 5286
Ruprecht 106

Cepheus
Palomar 1

Cetus
Whiting 1

Chamaeleon
ESO 37-01 (E3)

Columba
NGC 1851

Coma Berenices
NGC 4147
NGC 5024 (M53)
NGC 5053

Corona Australis
NGC 6541

Crater
Crater (Laevens 1)

Delphinus
NGC 6934
NGC 7006
Laevens 3

Eridanus
Eridanus

Hercules
NGC 6205 (M13)
NGC 6229
NGC 6341 (M92)
Palomar 14

Horologium
NGC 1261
Arp-Madore 1

Hydra
NGC 4590 (M68)
NGC 5694
Arp-Madore 4

Lepus
NGC 1904 (M79)

Libra
NGC 5897

Lupus
NGC 5824
NGC 5927
NGC 5986

Lynx
NGC 2419

Lyra
NGC 6779 (M56)

Musca
NGC 4372
NGC 4833
Van den Bergh-Hagen 140 (BH 140)

Norma
NGC 5946
FSR 1716
Lynga 7
RLGC 1

Ophiuchus
NGC 6171 (M107)
NGC 6218 (M12)
NGC 6235
NGC 6254 (M10)
NGC 6266 (M62)
NGC 6273 (M19)
NGC 6284
NGC 6287
NGC 6293
NGC 6304
NGC 6316
NGC 6325
NGC 6333 (M9)
NGC 6342
NGC 6355
NGC 6356
NGC 6366
NGC 6401
NGC 6402 (M14)
NGC 6426
NGC 6517
IC 1257
HP 1
Palomar 6
Palomar 15

Pavo
NGC 6752

Pegasus
NGC 7078 (M15)
Palomar 13

Puppis
NGC 2298

Pyxis
Pyxis

Sagitta
NGC 6838 (M71)
Palomar 10

Sagittarius
NGC 6440
NGC 6522
NGC 6528
NGC 6540
NGC 6544
NGC 6553
NGC 6558
NGC 6569
NGC 6624
NGC 6626 (M28)
NGC 6637 (M69)
NGC 6638
NGC 6642
NGC 6652
NGC 6656 (M22)
NGC 6681 (M70)
NGC 6715 (M54)
NGC 6717
NGC 6723
NGC 6809 (M55)
NGC 6864 (M75)
2MS-GC01
2MS-GC02
Arp 2
Van den Bergh-Hagen 261 (BH 261)
Djorgovski 2 (Djorg 2)
Palomar 8
Sagittarius II (Laevens 5)
Terzan 5
Terzan 7
Terzan 8
Terzan 9
Terzan 10
Terzan 12
UKS 1
VVV-CL001

Scorpius
NGC 6093 (M80)
NGC 6121 (M4)
NGC 6139
NGC 6144
NGC 6256
NGC 6380
NGC 6388
NGC 6441
NGC 6453
NGC 6496
Djorgovski 1 (Djorg 1)
ESO 452-SC11
FSR 1758
Liller 1
Terzan 1
Terzan 2
Terzan 3
Terzan 4
Terzan 6
Tonantzintla 2 (Ton 2)

Sculptor
NGC 288

Scutum
NGC 6712
Mercer 5
RLGC 2

Serpens (Caput)
NGC 5904 (M5)
Palomar 5

Serpens (Cauda)
NGC 6535
NGC 6539
IC 1276

Sextans
Palomar 3

Telescopium
NGC 6584

Tucana
NGC 104 (47 Tuc)
NGC 362

Ursa Major
Palomar 4

Vela
NGC 3201

Virgo
NGC 5634

References

Fundamental parameters of Galactic globular clusters (as of May 2021)
https://people.smp.uq.edu.au/HolgerBaumgardt/globular/
Accessed: November 29, 2021

A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty
The GRAVITY Collaboration, R. Abuter, A. Amorim, M. Bauböck, J. P. Berger, H. Bonnet, W. Brandner, Y. Clénet, V. Coudé du Foresto, P. T. de Zeeuw
A&A, 625 (2019) L10

An Almost-Total Partial Lunar Eclipse

Tonight, half of the world—including the U.S.—will be treated to a partial lunar eclipse that is so deep that it is almost total. At mid-eclipse, which occurs at 3:02:56 a.m. CST, only about 45 arcseconds of the Moon’s south-southeastern limb (as seen in the sky) will extend beyond the Earth’s umbral shadow into the penumbral shadow. This is extraordinary. Tonight’s eclipse will be the longest partial lunar eclipse since February 18, 1440, and a partial lunar eclipse this long won’t occur again until February 8, 2669.

Here is the time for each important event during the eclipse, given in Central Standard Time, and—allowing for time zone corrections—the same everywhere the eclipse is visible, plus local circumstances for Dodgeville, Wisconsin.

Time (CST)EventAltitude
12:02:09 a.m.Penumbral Eclipse Begins65˚
1:18:43 a.m.Partial Eclipse Begins58˚
3:02:56 a.m.Greatest Eclipse42˚
4:47:07 a.m.Partial Eclipse Ends24˚
5:19:03 a.m.Astronomical Twilight Begins18˚
5:52:45 a.m.Nautical Twilight Begins12˚
6:03:44 a.m.Penumbral Eclipse Ends10˚
Partial Lunar Eclipse of Friday, November 19, 2021

The Moon is in the constellation Taurus for this eclipse, and you’ll enjoy seeing the Pleiades star cluster nearby become increasingly visible as the eclipse progresses towards maximum. Enjoy!

Animation courtesy of Shadow & Substance
https://www.shadowandsubstance.com

Seth Barnes Nicholson

American astronomer Seth Barnes Nicholson was born 130 years ago this day in Springfield, Illinois on November 12, 1891. He attended Drake University in Des Moines from 1908-1912, receiving a B.S. degree in physics (with an astronomy emphasis) in 1912. At Drake, Nicholson was inspired to pursue a career in astronomy by Prof. D. W. Morehouse (then astronomy professor and later president of Drake University). He went on to obtain a Ph.D. in astronomy at the University of California in 1915.

Even though Nicholson died in 1963, he held the distinction until the year 2000 of discovering more moons of Jupiter than anyone since Galileo. Both men discovered four satellites each. Their record has now been surpassed. Graduate student Scott Sheppard and his colleagues at the University of Hawaii discovered 10 new moons of Jupiter in 2000 using an 88-inch telescope and a sensitive CCD camera atop Mauna Kea in Hawaii. Jupiter is now known to harbor 79 moons.

While at Drake, undergraduates Seth Nicholson and his wife-to-be Alma Stotts calculated the orbit of an asteroid discovered by Joel Metcalf in 1909. In those days before electronic computers, the privilege of naming an asteroid usually went not to the discoverer but to the person calculating its orbit! So, in 1911, the asteroid became known as 694 Ekard—which is “Drake” spelled backwards. One wonders why they didn’t choose the name Drake, because not until 2001 was an asteroid given that name. 9022 Drake was discovered in 1988 by Carolyn & Eugene Shoemaker and it is named after Michael J. Drake (1946-2011). Discovered just a year later—though numbered earlier (requires an accurate orbit)—and receiving a name only in 2015, asteroid 4772 Frankdrake is named after SETI pioneer Frank Drake (1930-).

Double Star Discovery: TYC 724-273-1

On 20 Oct 2021 UT, I observed the star TYC 724-273-1 in the constellation Orion being covered up by the asteroid 444 Gyptis. The star disappeared at 5:31:53.856 UT and reappeared at 5:32:10.506, a duration of 16.65 seconds.

The published apparent visual magnitude of this star is 11.5 and the published apparent visual magnitude of 444 Gyptis at the time of the event is 12.5.

The combined magnitude (mc) of star + asteroid just before (and after) the occultation event is given by

m_{c}=m_{o}-2.5\log_{10}\left (10^{0.4(m_{o}-m_{*})}+1  \right )

where mo is the magnitude of the asteroid
     and m* is the magnitude of the star

This gives us a combined magnitude of 11.14 just before the occultation.

While the asteroid is covering up the star, you should only see the asteroid, so the magnitude should decrease from 11.14 to 12.5, a magnitude drop of 1.36 magnitudes.

Much to my surprise, I observed a magnitude drop of only 0.54.

Is it possible that 444 Gyptis only covered up one component of a previously undiscovered double star? That idea is bolstered by the fact that the event occurred 14.8 seconds earlier than predicted, a full 3.7σ early.

Entertaining the double-star idea, our task is to determine the magnitudes of the two blended stars and which one got covered up. Let us call the magnitudes of the two components m*1 and m*2, with m*1 being the component that got covered. We already know that m*1 + m*2 must equal m* = 11.5. We also know that the observed magnitude drop of the m*1 plus the unobserved magnitude drop that the m*2 star would have had must equal the expected magnitude drop of 1.36. This gives us enough information to calculate m*1 and m*2 individually.

m_{*1} = -\log_{10}\left (10^{-\left (m_{c}+\Delta m_{obs}  \right )/2.5}-10^{-0.4m_{o}}  \right )/0.4

m_{*2} = -\log_{10}\left (10^{-\left (m_{*}/2.5\right )}-10^{-0.4m_{*1}}  \right )/0.4

where mo is the magnitude of the asteroid
     and m* is the magnitude of the star
     and mc is the magnitude of the star + asteroid
     and m*1 is the magnitude of the occulted star component
     and m*2 is the magnitude of the unocculted star component
     and Δmobs is the observed magnitude drop

This gives us a magnitude of 12.36 for the occulted component and 12.15 for the unocculted component. Thus we can see that I observed the fainter component of the double star being occulted by asteroid 444 Gyptis.

Finally, we can do an extra check to make sure that the magnitudes of the two star components plus the asteroid equals the combined magnitude of 11.14 we expected right before the occultation occurred.

m_{c}=-2.5\log_{10}\left (10^{-0.4m_{*1}}+10^{-0.4m_{*2}}+10^{-0.4m_{o}}  \right )

Here’s a little SAS program I wrote to do the calculations.

data magdrop;
   format mstar mastr mcomb pdelm odelm mstr1 mstr2 mtot 5.2;
   mstar = 11.5;
   mastr = 12.5;
   odelm = 0.54;
   x = 0.4*(mastr - mstar);
   mcomb = mastr - 2.5*log10(10**x + 1);
   pdelm = mastr - mcomb;
   mstr1 = log10(10**((mcomb+odelm)/-2.5) - 10**(-0.4*mastr))/-0.4;
   mstr2 = log10(10**(mstar/-2.5) - 10**(-0.4*mstr1))/-0.4;
   mtot = -2.5*log10(10**(-0.4*mstr1)+10**(-0.4*mstr2)+10**(-0.4*mastr));
   file print;
   put 'Published Magnitude of Occulted Star = ' mstar;
   put 'Magnitude of Asteroid = ' mastr;
   put 'Combined Magnitude Right Before Occultation = ' mcomb;
   put 'Predicted Magnitude Drop = ' pdelm;
   put 'Observed Magnitude Drop = ' odelm;
   if (odelm/pdelm > 0.5 and mstr1 > mstr2) or
      (odelm/pdelm < 0.5 and mstr1 < mstr2) then do;
      put 'Magnitude of Star Component Occulted = ' mstr2;
      put 'Magnitude of Star Component Not Occulted = ' mstr1;
   end;
   else do;
      put 'Magnitude of Star Component Occulted = ' mstr1;
      put 'Magnitude of Star Component Not Occulted = ' mstr2;
   end;
   put 'Total Magnitude of Both Star Components + Asteroid = ' mtot;
run;

Published Magnitude of Occulted Star = 11.50                                                      
Magnitude of Asteroid = 12.50                                                                     
Combined Magnitude Right Before Occultation = 11.14                                               
Predicted Magnitude Drop = 1.36                                                                   
Observed Magnitude Drop = 0.54                                                                    
Magnitude of Star Component Occulted = 12.36                                                      
Magnitude of Star Component Not Occulted = 12.15                                                  
Total Magnitude of Both Star Components + Asteroid = 11.14