## Supernovae in the Milky Way

The first recorded supernova in our Milky Way galaxy (or anywhere else, for that matter) was seen to blaze forth in the constellation Centaurus by astute Chinese astronomers in 185 AD. Including that one, only seven confirmed supernovae have been observed in our Milky Way galaxy, though thousands are discovered each year in other galaxies.

Supernova light reached Earth in AD 185, 393, 1006, 1054, 1181, 1572, and 1604. All seven of these events occurred before the invention of the telescope. Are we overdue for another supernova? Well, given this ridiculously small sample, we can endeavor to do some simple “statistics”. The shortest recorded interval between two Milky Way supernovae was 32 years between 1572 and 1604. The longest interval has been 613 years, between the supernovae of 393 and 1006 (assuming none went unnoticed). On average then (such as it is), we “should” have seen a Milky Way supernova around 1841, and using the longest interval of 613 years, we might be expecting one by the year 2217. Undoubtedly, some supernovae in the Milky Way have escaped detection because they lay behind thick interstellar clouds.

The big mystery to me is why are there no recorded supernova events prior to 185 AD? The earliest extant records of astronomical events go back at least as far as 2316 BC (a comet in the constellation Crater was recorded by Chinese astronomers), but in the intervening 2,500 years there has been no mention of anything that could be attributed to a supernova. Or has there? Some writings before and after 185 AD suggest possible supernovae, but until a supernova remnant is identified, we need to look for other explanations.

Here follows a table of the known observed Milky Way supernovae. Of course, other supernova remnants have been discovered in our Milky Way galaxy, but no record has yet been discovered describing these events. Many of them predate recorded history.

In the table below, you’ll note that these supernovae tend to lie close to the galactic plane (galactic latitude b = 0°)—not at all surprising considering that’s where most of the stars are.

## Some Early Piano Music by Robert Schumann

I discovered the music of Johannes Brahms before that of Robert Schumann, but I revere the latter composer now as well. Knowing much of the music of both, there is no question that Robert Schumann had a huge influence on Brahms. Both wrote four symphonies, all eight of which are favorites of mine.

But here we turn our attention to some of the early piano music of Robert Schumann, completed when Schumann was in his 20s, before he was finally able to marry Clara Wieck, and before his first symphony.

These are performances of considerable beauty, passion, and sensitivity by French pianist Lise de la Salle. I highly recommend this CD (Naïve V 5364). The recording is excellent, and De la Salle seems to have an innate understanding of this music and its often rapidly changing moods, a delight throughout.

The works performed are Scenes from Childhood, op. 15; Abegg Variations, op. 1; and Fantasie in C Major, op. 17.

There are thirteen pieces in Scenes from Childhood. The most famous of these is No. 7 Träumerei (Dreaming), but I also especially like No. 1 (Of foreign lands and peoples) and No. 2 (A curious story).

1. Of foreign lands and peoples
2. A curious story
3. Blind man’s buff
5. Happy enough
6. An important event
7. Dreaming
8. At the fireside
9. Knight of the hobby-horse
10. Almost too serious
11. Frightening
12. Child falling asleep
13. The poet speaks

This is followed by the Schumann’s first published work, the Abegg Variations, op. 1.

The disc concludes with the three-movement work, Fantasie in C Major, op. 17, arguably Schumann’s piano masterpiece, and a real tour de force in this performance by Lise de la Salle. When he wrote this piece, Schumann was already beginning to suffer from a mental disorder that would tragically claim his life only 20 years later—an illness with a physical origin that no doubt today could be easily cured.

For an excellent introduction to Robert Schumann and his wife, Clara Wieck Schumann—a piano virtuoso, composer, and teacher of considerable talent—I wholeheartedly recommend the eight-part video course from Robert Greenberg, “Great Masters: Robert and Clara Schumann – Their Lives and Music” (The Great Courses, Course No. 759).

Even though it is a highly fictionalized account, I would also recommend the 1947 movie Song of Love, starring the incomparable Katharine Hepburn as Clara Wieck Schumann, Paul Henreid as Robert Schumann, and Robert Walker as Johannes Brahms.

## Zodiacal Light 2021

In 2021, 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 2021
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
Zodiacal Light 6:49 – 7:26 p.m. West
31
Zodiacal Light 6:50 – 7:50 p.m. West

 February 2021
SUN MON TUE WED THU FRI SAT
1
Zodiacal Light 6:51 – 7:51 p.m. West
2
Zodiacal Light 6:52 – 7:52 p.m. West
3
Zodiacal Light 6:53 – 7:53 p.m. West
4
Zodiacal Light 6:54 – 7:54 p.m. West
5
Zodiacal Light 6:56 – 7:56 p.m. West
6
Zodiacal Light 6:57 – 7:57 p.m. West
7
Zodiacal Light 6:58 – 7:58 p.m. West
8
Zodiacal Light 6:59 – 7:59 p.m. West
9
Zodiacal Light 7:00 – 8:00 p.m. West
10
Zodiacal Light 7:02 – 8:02 p.m. West
11
Zodiacal Light 7:03 – 8:03 p.m. West
12
Zodiacal Light 7:04 – 8:04 p.m. West
13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28
Zodiacal Light 7:23 – 7:36 p.m. West

 March 2021
SUN MON TUE WED THU FRI SAT
1
Zodiacal Light 7:25 – 8:25 p.m. West
2
Zodiacal Light 7:26 – 8:26 p.m. West
3
Zodiacal Light 7:27 – 8:27 p.m. West
4
Zodiacal Light 7:28 – 8:28 p.m. West
5
Zodiacal Light 7:29 – 8:29 p.m. West
6
Zodiacal Light 7:31 – 8:31 p.m. West
7
Zodiacal Light 7:32 – 8:32 p.m. West
8
Zodiacal Light 7:33 – 8:33 p.m. West
9
Zodiacal Light 7:34 – 8:34 p.m. West
10
Zodiacal Light 7:36 – 8:36 p.m. West
11
Zodiacal Light 7:37 – 8:37 p.m. West
12
Zodiacal Light 7:38 – 8:38 p.m. West
13
Zodiacal Light 7:40 – 8:40 p.m. West
14
Zodiacal Light 8:41 – 9:41 p.m. West
15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
Zodiacal Light 9:03 – 10:03 p.m. West
31
Zodiacal Light 9:04 – 10:04 p.m. West

 April 2021
SUN MON TUE WED THU FRI SAT
1
Zodiacal Light 9:05 – 10:05 p.m. West
2
Zodiacal Light 9:07 – 10:07 p.m. West
3
Zodiacal Light 9:08 – 10:08 p.m. West
4
Zodiacal Light 9:10 – 10:10 p.m. West
5
Zodiacal Light 9:11 – 10:11 p.m. West
6
Zodiacal Light 9:13 – 10:13 p.m. West
7
Zodiacal Light 9:14 – 10:14 p.m. West
8
Zodiacal Light 9:16 – 10:16 p.m. West
9
Zodiacal Light 9:17 – 10:17 p.m. West
10
Zodiacal Light 9:19 – 10:19 p.m. West
11
Zodiacal Light 9:20 – 10:20 p.m. West
12
Zodiacal Light 9:22 – 10:22 p.m. West
13
Zodiacal Light 9:24 – 10:24 p.m. West
14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30

 May 2021
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 2021
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 2021
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 2021
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

 September 2021
SUN MON TUE WED THU FRI SAT
1 2 3 4
5 6
Zodiacal Light 3:52 – 4:52 a.m. East
7
Zodiacal Light 3:53 – 4:53 a.m. East
8
Zodiacal Light 3:54 – 4:54 a.m. East
9
Zodiacal Light 3:56 – 4:56 a.m. East
10
Zodiacal Light 3:57 – 4:57 a.m. East
11
Zodiacal Light 3:58 – 4:58 a.m. East
12
Zodiacal Light 4:00 – 5:00 a.m. East
13
Zodiacal Light 4:01 – 5:01 a.m. East
14
Zodiacal Light 4:02 – 5:02 a.m. East
15
Zodiacal Light 4:04 – 5:04 a.m. East
16
Zodiacal Light 4:05 – 5:05 a.m. East
17
Zodiacal Light 4:06 – 5:06 a.m. East
18
Zodiacal Light 4:08 – 5:08 a.m. East
19
Zodiacal Light 4:59 – 5:09 a.m. East
20 21 22 23 24 25
26 27 28 29 30

 October 2021
SUN MON TUE WED THU FRI SAT
1 2
3 4 5
Zodiacal Light 4:28 – 5:28 a.m. East
6
Zodiacal Light 4:30 – 5:30 a.m. East
7
Zodiacal Light 4:31 – 5:31 a.m. East
8
Zodiacal Light 4:32 – 5:32 a.m. East
9
Zodiacal Light 4:33 – 5:33 a.m. East
10
Zodiacal Light 4:34 – 5:34 a.m. East
11
Zodiacal Light 4:35 – 5:35 a.m. East
12
Zodiacal Light 4:37 – 5:37 a.m. East
13
Zodiacal Light 4:38 – 5:38 a.m. East
14
Zodiacal Light 4:39 – 5:39 a.m. East
15
Zodiacal Light 4:40 – 5:40 a.m. East
16
Zodiacal Light 4:41 – 5:41 a.m. East
17
Zodiacal Light 4:42 – 5:42 a.m. East
18
Zodiacal Light 5:03 – 5:43 a.m. East
19 20 21 22 23
24 25 26 27 28 29 30
31

 November 2021
SUN MON TUE WED THU FRI SAT
1 2 3 4
Zodiacal Light 5:03 – 6:03 a.m. East
5
Zodiacal Light 5:04 – 6:04 a.m. East
6
Zodiacal Light 5:05 – 6:05 a.m. East
7
Zodiacal Light 4:06 – 5:06 a.m. East
8
Zodiacal Light 4:07 – 5:07 a.m. East
9
Zodiacal Light 4:08 – 5:08 a.m. East
10
Zodiacal Light 4:09 – 5:09 a.m. East
11
Zodiacal Light 4:10 – 5:10 a.m. East
12
Zodiacal Light 4:12 – 5:12 a.m. East
13
Zodiacal Light 4:13 – 5:13 a.m. East
14
Zodiacal Light 4:14 – 5:14 a.m. East
15
Zodiacal Light 4:15 – 5:15 a.m. East
16
Zodiacal Light 4:16 – 5:16 a.m. East
17
Zodiacal Light 5:06 – 5:17 a.m. East
18 19 20
21 22 23 24 25 26 27
28 29 30

 December 2021
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

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.