04/10/2019 – Ephemeris Extra – Event Horizon Telescope reveals the black hole in galaxy M87
At 10 a.m. I found the live feed from the National Science Foundation presenting the results of the Event Horizon Telescope. It was one of four simultaneous presentations around the world at that hour. The buzz beforehand was that they would present the image of the black hole in our galaxy Sagittarius A*. It was not. The image presented was of the black hole in the galaxy M87, some 55 million light years away. It turns out that The black hole in M87 is easier to image. Our black hole appears to be too variable in brightness for this first attempt. The M87 black hole has a mass of 6.5 billion times that of our sun. Our black hole has a mass of about 3 million suns. The size of a black hole’s event horizon is proportional to its mass. So the M87 black hole is about 2,000 times larger than our black hole, but about 2,000 times farther away. So they would appear to be the same size on the sky.
The first image of the black hole in M87. Credit Event Horizon Telescope/Katie Bouman*.
The round spot in the center is not a shadow, but the event horizon itself. It is black because no light can escape it. The ring around it is the accretion disc of material spiraling in to the black hole. I believe the disc is close to perpendicular to our line of sight, but not close. The brightest part near the bottom is material that is approaching us, while the dimmer part above is material flowing away.
There are many articles and a video of the news conference by pointing you favorite search engine to M87 black hole.
About M87: More formally Messier 87, is a galaxy near the center of a vast cluster of galaxies about 55 million light years from us. Charles Messier found it in 1781 while searching for comets. He recorded it as object number 87 on his list of fuzzy objects that didn’t move and thus were not a comet. We amateur astronomers use his Messier Catalog to view these, what we call, deep sky objects. M87 is a giant elliptical galaxy that was also a radio source called Virgo A.
The Wikipedia article Messier 87 has already been updated to include the results presented of earlier today.
* Update: Dr. Katherine Bouman AKA Katie Bouman lead the team that created the algorithm that processed the data from the eight radio telescopes of the Event Horizon Telescope. Her ideas on how to perform this feat of mathematical and computer wizardry were presented in a TED Talk in 2016.
04/10/2019 – Ephemeris – Looking for the bright planets for this week
Ephemeris for Wednesday, April 10th. Today the Sun will be up for 13 hours and 13 minutes, setting at 8:21, and it will rise tomorrow at 7:05. The Moon, 2 days before first quarter, will set at 2:04 tomorrow morning.
Let’s look at the planets for this week. Mars will be in the western sky this evening, to the right of the V-shaped stars of the face of Taurus the bull. It will set at 12:27 a.m. In the morning sky we have Jupiter which will rise tomorrow at 1:35 a.m. in the east-southeast. It is second to Venus in brightness. Saturn will be next to rise at 3:21 a.m., also in the east-southeast. Venus will rise at 6:05 a.m. again in the east-southeast. By 6:30 in the morning they will be strung out from the southeast to the south. Venus will remain in our morning sky until August when it passes behind the Sun. Tiny Mercury may be glimpsed a bit left and just below Venus in the bright twilight.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars and the Moon in the evening at 9:30 p.m. April 10, 2019. Click on the image to enlarge. Created using Stellarium.
The Moon as it might appear in binoculars or a small telescope tonight at 9 p.m. April 10, 2019. Created using Stellarium.
Morning planets at 6:30 a.m. April 11, 2019. Click on the image to enlarge. Created using Stellarium.
Jupiter, Saturn and Venus with the same magnification at 6:30 a.m. tomorrow morning April 11, 2019. 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 April 10, 2019. The night ends on the left with sunrise on the 11th. Click on the image to enlarge. Created using my LookingUp program.
04/09/2019 – Ephemeris – Tomorrow we may be able to see the supermassive black hole at the center of our galaxy
Ephemeris for Tuesday, April 9th. Today the Sun will be up for 13 hours and 10 minutes, setting at 8:20, and it will rise tomorrow at 7:07. The Moon, 3 days before first quarter, will set at 1:00 tomorrow morning.
There’s a great bit of excitement in astronomical circles for tomorrow’s release of an image of the event horizon of the supermassive black hole at the center of our Milky Way Galaxy, 27 thousand light years away. The black hole is designated Sagittarius A*. Pronounced Sagittarius A Star. Sagittarius is the constellation it’s located in, capital A for the first radio source found in that constellation and an asterisk, pronounced Star. Eight highly accurate radio telescopes located from Greenland to the south pole, from Hawaii to Europe simultaneously record signals and record them to computer disks. The data are processed together to produce an image with the resolving power of a telescope the diameter of the Earth. The event horizon is smaller than our solar system.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Event Horizon Telescope component radio telescopes. Credits: © APEX, IRAM, G. Narayanan, J. McMahon, JCMT/JAC, S. Hostler, D. Harvey, ESO/C. Malin
For more information see this news article from the AAAS Science Magazine: https://www.sciencemag.org/news/2019/04/here-s-what-scientists-think-black-hole-looks.
For a non-technical explanation of black holes and the event horizon check this out: https://www.sciencealert.com/black-holes.
04/08/2019 – Ephemeris – How to find Polaris, the North Star
Ephemeris for Monday, April 8th. Today the Sun will be up for 13 hours and 7 minutes, setting at 8:18, and it will rise tomorrow at 7:09. The Moon, 3 days past new, will set at 11:54 this evening.
The most useful of the navigation stars for the average person is Polaris, the North Star or Pole Star. It is very close to the point in the sky that the Earth’s axis points to in the north. Currently it is about three-quarters of a degree from the pole, about one and a half moon diameters. In 2110 or thereabouts it will approach to slightly less than a moon diameter from the pole before slowly heading away. Polaris is always closer to true north than a magnetic compass in Michigan. To find it use the two stars in front of the Big Dipper’s bowl to point to it. This time of year the Big Dipper is above Polaris, so the pointer stars, that’s what they are called, point down to it. Polaris is at the end of the handle of the faint Little Dipper. The reason for Polaris’ motion is the slow 26,000 year wobbling of the Earth’s axis, called precession.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Ursa Major and Minor, the Big and Little Dippers. See how the two stars at the front of the bowl point to Polaris. It happens that the pointer stars are close to the 11th hour of right ascension (longitude in the sky). The right ascension lines converge at the north celestial pole, just as the longitude lines converge at the Earth’s north pole. Created using Stellarium.
The year I was born, 1941, Polaris was a whole degree from the celestial north pole.
If you’ve ever wondered why right ascension is in hours instead of degrees it’s because the Earth rotates within the celestial sphere, so it’s easier to keep track of the east-west position in the sky by using a clock that set to gain 3 minutes and 56 seconds a day. Such a clock keeps sidereal (star) time rather than solar (sun) time. One hour equals 15 angular degrees or 4 minutes a degree.
04/05/2019 – Ephemeris – Starpardy Quiz at tonight’s meeting of the GTAS
Ephemeris for Friday, April 5th. Today the Sun will be up for 12 hours and 58 minutes, setting at 8:15, and it will rise tomorrow at 7:14. The Moon is new today, and won’t be visible.
An astronomical quiz between the astronomy students and members of the Northwestern Michigan College Astronomy Club vs. the Grand Traverse Astronomical Society will be held tonight at 8 p.m. at the NMC Observatory. Folks attending can watch and learn or join one of the teams. The format is that of the popular Jeopardy show. These quizzes used to be called Star Bowls, after the old College Bowl TV shows. It’s been morphed into the Jeopardy format over the years. The answers and questions are on basic astronomy: constellations, planets, the Earth, astronomical history, current events and the dreaded potpourri. So come, enjoy the fun. After the quiz there will be, weather permitting, a star party
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
04/04/2019 – Ephemeris – A very hairy constellation
Ephemeris for Thursday, April 4th. Today the Sun will be up for 12 hours and 55 minutes, setting at 8:13, and it will rise tomorrow at 7:16. The Moon, 1 day before new, will rise at 7:51 tomorrow morning.
Midway up the sky in the east-southeast at 10 p.m. is a tiny sprinkle of faint stars arrayed to look like several strands of hair. It’s the constellation of Coma Berenices, or Berenice’s hair. The whole group will fit in the field of a pair of binoculars, which is the best way to see it, and will also show more stars. The cluster contains about 50 stars and lies at a distance of 280 light years from us, which makes it the second closest star cluster. The closest being the Hyades, that is the face of Taurus the bull now about to set in the west. The star cluster appears to be about 480 million years old. It is an open or galactic star cluster, born along the plane of the Milky Way. It appears away from the milky band due to its closeness to us.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Coma Berenices finder chart 10 p.m., April 4th. Created using Stellarium.
Approximate 7 power binocular field of view of the Coma Berenices Cluster. Created using Cartes du Ciel (Sky Charts).
04/03/2019 – Ephemeris – Let’s check out the bright planets for this week
Ephemeris for Wednesday, April 3rd. Today the Sun will be up for 12 hours and 52 minutes, setting at 8:12, and it will rise tomorrow at 7:18. The Moon, 2 days before new, will rise at 7:27 tomorrow morning.
Let’s look at the planets for this week. Mars will be in the western sky this evening, to the right of the V shaped stars of the face of Taurus the bull. It will set at 12:31 a.m. In the morning sky we have Jupiter which will rise tomorrow at 2:02 a.m. in the east-southeast. It is second to Venus in brightness. Saturn will be next to rise at 3:48 a.m., also in the east-southeast. Venus will rise at 6:13 a.m. again in the east-southeast. By 7 in the morning they will be strung out from the southeast to the south. Venus will remain in our morning sky until August when it passes behind the Sun. It will emerge to become a bright addition to our winter and spring evening skies later this year and next. Mercury will be
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mars in the evening at 9 p.m. April 3, 2019. Click on the image to enlarge. Created using Stellarium.
Morning planets at 6:45 a.m. April 4, 2019. Click on the image to enlarge. Created using Stellarium.
Jupiter, Saturn and Venus with the same magnification at 6:45 a.m. tomorrow morning April 4, 2019. 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 April 3, 2019. The night ends on the left with sunrise on the 4th. Click on the image to enlarge. Created using my LookingUp program.
04/02/2019 – Ephemeris – Hydra the longest constellation
Ephemeris for Tuesday, April 2nd. Today the Sun will be up for 12 hours and 49 minutes, setting at 8:11, and it will rise tomorrow at 7:20. The Moon, 3 days before new, will rise at 7:03 tomorrow morning.
In the south and southeastern sky at 10 p.m. can be found the constellation of Hydra the water snake. Unlike the monster of the same name this Hydra has but one head, which is its most distinctive part. At 10 p.m. look to the south. The head of Hydra is located below a line from the constellation Leo the Lion in the south and Gemini high in the west-southwest, and directly below Cancer the crab. Hydra’s head is a small but distinctive group of 6 stars that make a drooping loop to the right. The rest of Hydra wends its way diagonally to the southeastern horizon below the bright blue star Spica in Virgo. Some delineations of Hydra have the tail tickling the constellation Libra which is just about to rise at that time.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Hydra the water snake finder animation for 10 p.m. April 2nd.. Hydra is the longest of all the constellations. Click on the image to enlarge. Created using Stellarium and GIMP.
04/01/2019 – Ephemeris – Previewing April skies
Ephemeris for April Fools Day, Monday, April 1st. Today the Sun will be up for 12 hours and 46 minutes, setting at 8:10, and it will rise tomorrow at 7:22. The Moon, half way from last quarter to new, will rise at 6:37 tomorrow morning.
Last year we were fooled by an abundance of snow in April. Hopefully we won’t be tricked again. Daylight hours in the Interlochen/Traverse City area and will increase from 12 hours and 46 minutes today to 14 hours 11 minutes on the 30th. The altitude, or angle, of the Sun above the southern horizon at local noon will ascend from 50 degrees today to 60 degrees on the 30th. The altitude of the Sun in the Straits area will be a degree lower, but their daylight hours will be a bit longer. The actual time of local apparent noon this month for the Interlochen/Traverse City area, when the Sun passes due south, will be about 1:43 p.m. This month Mars will be our only evening planet.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
April Evening Star Chart
Star Chart for April 2019 (10 p.m. EDT April 15, 2019). Created using my LookingUp program. Click on image to enlarge.
The planets and stars are plotted for the 15th at 10 p.m. EST in the evening and 6 a.m. for the morning chart. These are the chart times. Note that Traverse City is located approximately 45 minutes behind our time meridian, West 75° longitude. (An hour 45 minutes behind our daylight saving time meridian during EDT). To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.
Note the chart times of 10 p.m. and 5 a.m. are for the 15th. For each week before the 15th add ½ hour (28 minutes if you’re picky). For each week after the 15th subtract ½ hour. The planet positions are updated each Wednesday on this blog. For planet positions on dates other than the 15th, check the Wednesday planet posts on this blog.
April Morning Star Chart
Star Chart for April mornings 2019 (5 a.m. EST April 15, 2019). Created using my LookingUp program. Click on image to enlarge.
For a list of constellation names to go with the abbreviations click here.
- Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
- Leaky dipper drips on Leo
- Follow the arc of the handle of the Big Dipper to the star Arcturus, and
- Extend like a spike to Spica,
- The Summer Triangle is in red.
- LyrR is the radiant of the Lyrid meteor shower that peaks on the 22nd.
Twilight Limits, Nautical and Astronomical
| EDT | |||||||
| Traverse City |
Morning twilight | Evening twilight | Dark night | Moon | |||
| Date | Astro. | Nautical | Nautical | Astro. | Start | End | Illum. |
| 2019-04-01 | 5h47m | 6h24m | 21h17m | 21h53m | 21h53m | 5h47m | 0.13 |
| 2019-04-02 | 5h45m | 6h22m | 21h18m | 21h55m | 21h55m | 5h45m | 0.07 |
| 2019-04-03 | 5h43m | 6h20m | 21h20m | 21h57m | 21h57m | 5h43m | 0.03 |
| 2019-04-04 | 5h41m | 6h18m | 21h21m | 21h58m | 21h58m | 5h41m | 0 |
| 2019-04-05 | 5h38m | 6h16m | 21h22m | 22h00m | 22h00m | 5h38m | 0 |
| 2019-04-06 | 5h36m | 6h14m | 21h24m | 22h01m | 22h01m | 5h36m | 0.02 |
| 2019-04-07 | 5h34m | 6h12m | 21h25m | 22h03m | 22h48m | 5h34m | 0.06 |
| 2019-04-08 | 5h32m | 6h10m | 21h27m | 22h05m | 23h54m | 5h32m | 0.12 |
| 2019-04-09 | 5h30m | 6h08m | 21h28m | 22h06m | – | 5h30m | 0.2 |
| 2019-04-10 | 5h27m | 6h06m | 21h30m | 22h08m | 1h00m | 5h27m | 0.3 |
| 2019-04-11 | 5h25m | 6h04m | 21h31m | 22h10m | 2h04m | 5h25m | 0.41 |
| 2019-04-12 | 5h23m | 6h02m | 21h33m | 22h11m | 3h03m | 5h23m | 0.53 |
| 2019-04-13 | 5h21m | 6h00m | 21h34m | 22h13m | 3h55m | 5h21m | 0.64 |
| 2019-04-14 | 5h19m | 5h58m | 21h36m | 22h15m | 4h40m | 5h19m | 0.75 |
| 2019-04-15 | 5h16m | 5h56m | 21h37m | 22h16m | – | – | 0.85 |
| 2019-04-16 | 5h14m | 5h54m | 21h39m | 22h18m | – | – | 0.93 |
| 2019-04-17 | 5h12m | 5h52m | 21h40m | 22h20m | – | – | 0.93 |
| 2019-04-18 | 5h10m | 5h50m | 21h42m | 22h22m | – | – | 0.98 |
| 2019-04-19 | 5h07m | 5h48m | 21h43m | 22h24m | – | – | 1 |
| 2019-04-20 | 5h05m | 5h46m | 21h45m | 22h25m | – | – | 0.99 |
| 2019-04-21 | 5h03m | 5h44m | 21h46m | 22h27m | 22h27m | 23h19m | 0.96 |
| 2019-04-22 | 5h01m | 5h42m | 21h48m | 22h29m | 22h29m | – | 0.9 |
| 2019-04-23 | 4h59m | 5h40m | 21h49m | 22h31m | 22h31m | 0h24m | 0.82 |
| 2019-04-24 | 4h56m | 5h38m | 21h51m | 22h33m | 22h33m | 1h24m | 0.74 |
| 2019-04-25 | 4h54m | 5h36m | 21h52m | 22h34m | 22h34m | 2h16m | 0.64 |
| 2019-04-26 | 4h52m | 5h35m | 21h54m | 22h36m | 22h36m | 3h01m | 0.54 |
| 2019-04-27 | 4h50m | 5h33m | 21h55m | 22h38m | 22h38m | 3h39m | 0.45 |
| 2019-04-28 | 4h48m | 5h31m | 21h57m | 22h40m | 22h40m | 4h12m | 0.35 |
| 2019-04-29 | 4h45m | 5h29m | 21h58m | 22h42m | 22h42m | 4h41m | 0.26 |
| 2019-04-30 | 4h43m | 5h27m | 22h00m | 22h44m | 22h44m | 4h43m |
0.18 |
Twilight calendar was generated using Cartes du Ciel (Sky Charts).
See my blog post: Twilight Zone for the definitions of the different periods of twilight here: https://bobmoler.wordpress.com/2018/09/27/.
NASA Calendar of Planetary Events
Date Local Time Event
Apr 1 Mo Venus: 34.6° W
2 Tu 12:17 AM Moon-Venus: 3° N
2 Tu 07:01 PM Moon-Mercury: 4° N
5 Fr 04:50 AM New Moon
9 Tu 02:40 AM Moon-Mars: 5° N
9 Tu 11:43 AM Moon-Aldebaran: 2.2° S
11 Th 02:59 PM Mercury Elongation: 27.7° W
11 Th 07:59 PM Moon North Dec.: 22° N
12 Fr 02:08 PM Moon Ascending Node
12 Fr 03:06 PM First Quarter
13 Sa 04:12 PM Moon-Beehive: 0.2° N
14 Su 08:08 PM Mars-Aldebaran: 6.5° N
15 Mo 04:22 AM Moon-Regulus: 2.7° S
16 Tu 02:03 PM Mercury-Venus: 4.3° N
16 Tu 06:02 PM Moon Perigee: 364200 km
19 Fr 07:12 AM Full Moon
22 Mo 07:58 PM Lyrid Shower: ZHR = 20
22 Mo 08:06 PM Uranus Conjunction
23 Tu 07:36 AM Moon-Jupiter: 1.8° S
24 We 05:22 PM Moon South Dec.: 22.1° S
25 Th 10:38 AM Moon-Saturn: 0.4° N
25 Th 11:02 AM Moon Descending Node
26 Fr 06:18 PM Last Quarter
28 Su 02:20 PM Moon Apogee: 404600 km
May 1 We Venus: 27.8° W
All event times are given for UTC-5 hr: Eastern Standard or UTC-4 hr: Daylight Saving Time starting April 10th.
Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC),
http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html.
If you go to the above site you can print out a list like the above for the entire year or calendar pages for your time zone.
Sun and Moon Rising and Setting Events
Ephemeris of Sky Events for NMC Observatory |
||||||||||
|
April, 2019 – Local time zone: EDT |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
Date |
Sun |
Twilight* |
Moon |
Illum |
||||||
|
Rise |
Set |
Hours |
End |
Start |
Phase |
R/S** |
Time |
Fractn |
||
|
Mon |
1 |
07:23a |
08:09p |
12:45 |
09:14p |
06:19a |
Rise |
06:37a |
10% |
|
|
Tue |
2 |
07:21a |
08:10p |
12:49 |
09:15p |
06:17a |
Rise |
07:02a |
5% |
|
|
Wed |
3 |
07:20a |
08:12p |
12:52 |
09:17p |
06:15a |
Rise |
07:26a |
2% |
|
|
Thu |
4 |
07:18a |
08:13p |
12:55 |
09:18p |
06:13a |
Rise |
07:50a |
0% |
|
|
Fri |
5 |
07:16a |
08:14p |
12:58 |
09:19p |
06:11a |
New |
Set |
08:37p |
1% |
|
Sat |
6 |
07:14a |
08:15p |
13:01 |
09:21p |
06:09a |
Set |
09:41p |
3% |
|
|
Sun |
7 |
07:12a |
08:17p |
13:04 |
09:22p |
06:07a |
Set |
10:47p |
7% |
|
|
Mon |
8 |
07:11a |
08:18p |
13:07 |
09:24p |
06:05a |
Set |
11:53p |
13% |
|
|
Tue |
9 |
07:09a |
08:19p |
13:10 |
09:25p |
06:03a |
Set |
12:59a |
21% |
|
|
Wed |
10 |
07:07a |
08:20p |
13:13 |
09:27p |
06:01a |
Set |
02:03a |
31% |
|
|
Thu |
11 |
07:05a |
08:22p |
13:16 |
09:28p |
05:59a |
Set |
03:02a |
41% |
|
|
Fri |
12 |
07:03a |
08:23p |
13:19 |
09:30p |
05:57a |
F Qtr |
Set |
03:54a |
52% |
|
Sat |
13 |
07:02a |
08:24p |
13:22 |
09:31p |
05:55a |
Set |
04:39a |
64% |
|
|
Sun |
14 |
07:00a |
08:25p |
13:25 |
09:33p |
05:53a |
Set |
05:18a |
74% |
|
|
Mon |
15 |
06:58a |
08:27p |
13:28 |
09:34p |
05:51a |
Set |
05:52a |
84% |
|
|
Tue |
16 |
06:57a |
08:28p |
13:31 |
09:35p |
05:49a |
Set |
06:23a |
91% |
|
|
Wed |
17 |
06:55a |
08:29p |
13:34 |
09:37p |
05:47a |
Set |
06:52a |
97% |
|
|
Thu |
18 |
06:53a |
08:30p |
13:37 |
09:38p |
05:45a |
Set |
07:22a |
100% |
|
|
Fri |
19 |
06:51a |
08:32p |
13:40 |
09:40p |
05:43a |
Full |
Rise |
08:55p |
99% |
|
Sat |
20 |
06:50a |
08:33p |
13:43 |
09:42p |
05:41a |
Rise |
10:08p |
97% |
|
|
Sun |
21 |
06:48a |
08:34p |
13:45 |
09:43p |
05:39a |
Rise |
11:18p |
92% |
|
|
Mon |
22 |
06:46a |
08:35p |
13:48 |
09:45p |
05:38a |
Rise |
12:24a |
85% |
|
|
Tue |
23 |
06:45a |
08:37p |
13:51 |
09:46p |
05:36a |
Rise |
01:23a |
77% |
|
|
Wed |
24 |
06:43a |
08:38p |
13:54 |
09:48p |
05:34a |
Rise |
02:15a |
68% |
|
|
Thu |
25 |
06:42a |
08:39p |
13:57 |
09:49p |
05:32a |
Rise |
03:00a |
59% |
|
|
Fri |
26 |
06:40a |
08:40p |
14:00 |
09:51p |
05:30a |
L Qtr |
Rise |
03:38a |
49% |
|
Sat |
27 |
06:39a |
08:41p |
14:02 |
09:52p |
05:28a |
Rise |
04:11a |
40% |
|
|
Sun |
28 |
06:37a |
08:43p |
14:05 |
09:54p |
05:26a |
Rise |
04:40a |
31% |
|
|
Mon |
29 |
06:36a |
08:44p |
14:08 |
09:55p |
05:24a |
Rise |
05:06a |
23% |
|
|
Tue |
30 |
06:34a |
08:45p |
14:11 |
09:57p |
05:23a |
Rise |
05:30a |
15% |
|
|
* Nautical Twilight |
||||||||||
|
** Moonrise or moonset, whichever occurs between sunset and sunrise |
||||||||||
03/29/2019 – Ephemeris – The Stars Mizar and Alcor in the Big Dipper
Ephemeris for Friday, March 29th. Today the Sun will be up for 12 hours and 36 minutes, setting at 8:06, and it will rise tomorrow at 7:27. The Moon, 1 day past last quarter, will rise at 5:03 tomorrow morning.
The most interesting star in the Big Dipper is Mizar and its dim companion Alcor. It is the second star from the end of the handle, where the bend in the handle takes place. Folks with good vision can see the dimmer star right next to Mizar. In ancient times it was used as an eye test for visual acuity for warriors. As such it was known as the “Horse and the Rider”. Mizar is second magnitude, in the second rank of star brightness invented by the Greek astronomer Hipparchus in the 2nd century BC. He ranked stars in 6 classes, from first magnitude for the brightest to 6th for the dimmest visible to the naked eye. Alcor comes in at 4th magnitude. It does suffer a bit by being very close to Mizar which is 6 times brighter.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
