Archive
04/25/11 – Ephemeris – The constellation of Corvus the crow
Monday, April 25th. The sun rises at 6:42. It’ll be up for 13 hours and 57 minutes, setting at 8:39. The moon, 1 day past last quarter, will rise at 3:32 tomorrow morning.
The small constellation of Corvus the crow is located low in the south southeast at 10 this evening. It’s made of 5 dim stars, but the pattern is a distinctive distorted box with two stars at the upper left marking that corner. To the right is a fainter constellation of a thick stemmed goblet called Crater. Both appear above the long constellation of Hydra the water snake who is slithering just above the southern horizon.. In Greek mythology Corvus, then white, was the god Apollo’s pet. Apollo once bid Corvus to take a cup and fetch him some water. Corvus however dallied and waited for an unripe fig to ripen. Corvus grabbed a snake and returned with a story as to how the snake had delayed him. The angry Apollo turned the crow and all crows to this day black.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Corvus, Crater and Hydra via Stellarium for April 25, 2011 near 10 p.m.
04/22/11 – Ephemeris – The constellation Hydra and public viewing tonight
Good Friday, Friday, April 22nd. The sun rises at 6:47. It’ll be up for 13 hours and 48 minutes, setting at 8:35. The moon, 2 days before last quarter, will rise at 1:57 tomorrow morning.
Hydra the Water snake is the longest of the constellations. Its head is a group of five stars in a close group below a line between Leo the Lion and Gemini the twins in the southwest. Its stars drop down and skirt the horizon and end in the southeast. It takes a low southern horizon to follow its body. The Northwestern Michigan College’s Rogers observatory will be open tonight starting at 9 p.m. for observation of the heavens and the front half of Hydra. The featured celestial object of the evening will be the ringed planet Saturn.. The viewing night will be hosted by the Grand Traverse Astronomical Society and the NMC Astronomical Association. There will be an alternate program if its cloudy.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Hydra via Stellarium for April 22, 2011 at 10 p.m.
04/21/11 – Ephemeris – Queen Berenice’s hair
Thursday, April 21st. The sun rises at 6:48. It’ll be up for 13 hours and 45 minutes, setting at 8:34. The moon, 3 days before last quarter, will rise at 1:10 tomorrow morning.
High in the southeast at 10 p.m. is a tiny and faint constellation of Coma Berenices, or Berenice’s hair. In it are lots of faint stars arrayed to look like several strands of hair. The whole group will fit in the field of a pair of binoculars, which will also show many more stars. The story behind it was that Berenice was the Queen of Egypt, whose husband was away at war. This was in the days when the Greeks ruled Egypt after Alexander conquered it. She offered her golden tresses to the gods for the king’s safe return. The hair, was placed in a temple. However the offering disappeared when the king returned. Ever since then the constellation of Coma Berenices has been seen to commemorate the queen’s sacrifice.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Coma Berenices via Stellarium
Only one of the three stars that mark the constellation belong to the Coma Berenices star cluster near the top of this image. The cluster is about 270 light years away, making it one of the closest star clusters to us.
Coma Berenice Finder Chart via Stellarium
Here’s a star chart based on this evening at 10 p.m. on locating Coma Berenices in the southeastern sky.
Note: Stellarium is a free program. See the right column for a link.
04/20/11 – Ephemeris – The bright planets visible this week
Wednesday, April 20th. The sun rises at 6:50. It’ll be up for 13 hours and 42 minutes, setting at 8:33. The moon, 3 days past full, will rise at 12:13 tomorrow morning.
It’s Wednesday and time again to take a look at the whereabouts of the bright planets for this week. The ringed planet Saturn is rising before sunset and will be visible in the southeast as it gets dark. It’s near the bright star Spica to its lower left. Spica has a blue tinge, while Saturn is yellowish. It will cross the meridian due south at 12:38 a.m. and will set at 6:30 a.m. In telescopes Saturn shows its rings which are a year and a half along their seven and a half year period of opening along with at least one satellite, the large moon Titan. Venus is brilliant in the morning sky and will rise at 5:51 a.m. in the east.. It is really a beautiful sight in the morning twilight, though disappointingly small in a telescope. Jupiter, Mars and Mercury are all too close to the direction of the sun to be visible.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
04/19/11 – Ephemeris – How the Great Bear got its long tail
Tuesday, April 19th. The sun rises at 6:52. It’ll be up for 13 hours and 39 minutes, setting at 8:32. The moon, 2 days past full, will rise at 11:05 this evening.
The Greeks and Romans who saw the Great Bear, the constellation we call Ursa Major, they also saw it having a long tail. We’re more likely to see the Big Dipper. The bowl of the Big Dipper is the bear’s rump, while the handle is that notorious tail. The Big Dipper is overhead at 10 p.m. this evening. Now, to how did the ancient Romans explained the long tail. According to one story a god threw the bear into the sky. I don’t care if you’re immortal or not, you wouldn’t grab the end of the bear with the teeth. However grabbing the tail apparently caused the tail to stretch, giving the long tail we see in our skies. While the skies are dark before moonrise, check out the bear. He’s all there from the tip of his nose to the end of his claws.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Here’s a quotation from Star Names Their Lore and Meaning by Richard Hinckley Allen:
The long tail of the Bear, a queer appendage to a comparitively taillessanimal, is thus accounted for by old Thomas Hood in his didactic style:
Scholar.
I marvell why (seeing she hath the forme of a beare) her tail should be so long.
Master.
Imagine that Jupiter, fearing to come too nigh unto her teeth, layde hold of her tayle, and thereby drew her up into heaven; so that she of herself being very weightie, and the distance from the earth to the heavens very great, there was a great likelihood that her taile must stretch. Other reason I know none.
My rather crude drawing of Ursa Major, the Great Bear
04/18/11 – Ephemeris – Paschal Full Moon
Monday, April 18th. The sun rises at 6:53. It’ll be up for 13 hours and 37 minutes, setting at 8:30. The moon, 1 day past full, will rise at 9:49 this evening.
Last night our time the moon was full. It was the Paschal full moon, the first full moon of spring, or officially after March 21st. Western Christian churches celebrate Easter at the Sunday following. That would be the 24th, just one day short of the latest possible date of Easter. Eastern churches use a slightly different calendar and a different calculation method, but this year they celebrate Easter the same date. The calculation methods were chosen to make Easter roughly coincide with Jewish Passover. Christian churches use a calendar based on the earth’s orbit of the sun, or actually the seasons, while the Jewish calendar is based on the lunar cycle. That’s also pretty close this year because Passover begins tonight at sundown.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
04/15/11 – Ephemeris – Naming lunar features
Friday, April 15th. The sun rises at 6:58. It’ll be up for 13 hours and 28 minutes, setting at 8:27. The moon, 2 days before full, will set at 5:41 tomorrow morning.
If you’ve notices that the names we use for features on the moon sound familiar when used in other contexts, you’re right. Lunar craters are named for astronomers, scientists, philosophers and explorers. The mountains on the moon are named for earthly mountain ranges. The great lava plains, misnames seas are given fanciful names like the Sea of Tranquility, which I usually leave in the original Latin. In this case Mare Tranquilitatis. The naming convention for craters pretty much holds for the other bodies of the solar system. The next bodies to get crater names will be Mercury, which the MESSENGER spacecraft went into orbit of last month and the asteroid Vesta, which the Dawn spacecraft will reach in July.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
See this Wikipedia article on planetary nomenclature.
04/14/11 – Ephemeris – The gibbous moon
Thursday, April 14th. The sun will rise at 7:00. It’ll be up for 13 hours and 25 minutes, setting at 8:25. The moon, half way from first quarter to full, will set at 5:13 tomorrow morning.
The moon tonight is in its gibbous phase. The word gibbous means hump backed. At this phase the moon is severely interfering with the dimmer stars. So looking at the moon with a telescope becomes a good option. The moon will be bright and ruin any dark adaption your eye had before looking at it. Remember the sun shines on the moon with the same strength that it does on the earth, since it’s at roughly the same distance from the sun as the earth. The brightest spot on the earth facing side of the moon will be emerging into the lunar morning light this evening. It will be showing that brightness in a few days, but now it is the crater at the upper left edge of the moon, just coming into light. It is the crater Aristarchus.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The gibbous moon for April 14, 2011. Created using Virtual Moon Atlas.
The crater Aristarchus is moving into the morning lunar daylight.
04/13/11 – Ephemeris – The Bright planets this week
Wednesday, April 13th. The sun will rise at 7:02. It’ll be up for 13 hours and 22 minutes, setting at 8:24. The moon, 2 days past first quarter, will set at 4:45 tomorrow morning.
It’s Wednesday and time again to take a look at the whereabouts of the bright planets for this week. The ringed planet Saturn is rising before sunset and will be visible low in the southeast as it gets dark. It will cross the meridian due south at 1:07 a.m. and will set at 7:12 a.m. In telescopes Saturn shows its rings which are a year and a half along their seven and a half year period of opening along with at least one satellite, the large moon Titan. Venus is brilliant in the morning sky and will rise at 6:00 a.m. in the east.. It is really a beautiful sight in the morning twilight, though disappointingly small in a telescope. Jupiter, Mars and Mercury are all too close to the direction of the sun to be visible.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
04/12/11 – Ephemeris – Saturn and its moon Titan
Tuesday, April 12th. The sun will rise at 7:04. It’ll be up for 13 hours and 19 minutes, setting at 8:23. The moon, 1 day past first quarter, will set at 4:16 tomorrow morning.
The planet Saturn, now rising up in the southeastern sky is always the most wonderful sight in a small telescope. The rings are slowly opening to the sun, however for us on the earth, whose orbit is tilted by about 2 and a half degrees to the Saturn’s orbit of the sun, the rings appear to be closing just a bit right now. After June they will open up again. Tonight a small telescope will also reveal Saturn’s largest satellite or moon which will be off the edge of the longest extent of the rings to the east of Saturn. Titan is the second largest moon in the solar system, after Jupiter’s Ganymede. It is larger than the planet Mercury and the only moon with a substantial atmosphere. Titan’s surface atmospheric pressure is slightly greater than the earth’s.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Saturn and some of its bright moons for April 12, 2011. Created using Cartes du Ciel
Titan is the easiest moon to see. Rhea is more difficult. The others being close to Saturn tonight may be impossible to spot. The free programs Cartes du Ciel and Stellarium will show the positions of Saturn’s satellites. See the Free Astronomical Software links in the right. Stellarium does have a problem getting the satellite brightness right, they’re too bright.
