Archive
03/29/2013 – Ephemeris – How we know this Sunday is Easter
Ephemeris for Good Friday, Friday, March 29th. The sun will rise at 7:28. It’ll be up for 12 hours and 38 minutes, setting at 8:06. The moon, 2 days past full, will rise at 11:14 this evening.
Wednesday was the day of the Paschal full moon, the full moon after the first day of spring, which is defined by Christian churches as March 21st. For the date of Easter the actual full moon isn’t used, but a rather complicated formula is used to find the new moon. There’s a complicated correction to then find the date of the full moon, which 2 days ago. This year that formula works out correctly. It can be a day off either way. The next Sunday then is Easter. Orthodox churches use the Julian calendar and a different formula but they’ll celebrate Easter on May 5th. The formula was set up to approximate the Jewish lunar calendar. It works out close this year because Passover started at sunset last Sunday night.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
03/29/2013 – Ephemeris –
Ephemeris for Thursday, March 28th. The sun will rise at 7:30. It’ll be up for 12 hours and 34 minutes, setting at 8:05. The moon, 1 day past full, will rise at 10:01 this evening.
Venus is passing superior conjunction with the sun today. Superior means Venus is passing behind, thought not directly behind the Sun. You can see it only in the images of the SOHO spacecraft. On the Internet google soho nasa to find the site. Our last inferior conjunction of Venus was the transit of Venus last June, when Venus crossed the face of the sun. Mars is about to pass in conjunction with the sun. All its conjunctions are superior. For about a month, starting April 4th. the satellites and rovers cannot receive transmissions from the earth due to the sun’s radio noise, so they are put into a passive state. The Deep Space Network on the earth can pick up their transmissions, though not well during this period due to its greater sensitivity.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Annotated SOHO LASCO C3 image of the sun, behind the occulting disk with Venus and Mars. Image: ESA, NASA
03/27/2013 – Ephemeris – Where’s Comet PanSTARRS and the bright planets this week?
Ephemeris for Wednesday, March 27th. The sun will rise at 7:32. It’ll be up for 12 hours and 31 minutes, setting at 8:04. The moon, at full today, will rise at 8:49 this evening.
It’s time to check out a comet and the two remaining bright planets for this week. Comet PanSTARRS is in the northwest, moving away from the sun, and getting a little higher in the sky as it moves northward rather than eastward. The comet will set at 10:26. The comet is now down to near 4th magnitude, as bright as a relatively faint naked eye star. Jupiter is located in the constellation of Taurus and is in the high southwest during the evening. It will set at 1:35 a.m. Jupiter is a wonderful sight in telescopes with its cloud bands and its moons which change positions each night. The other bright planet Saturn will rise at 10:43 p.m. in the east southeast. It’s located in eastern Virgo. It will pass due south at 3:55 a.m. Saturn is the most beautiful of planets in a telescope.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet PanSTARRS at about 9:15 p.m. from March 27 to April 2, 2013. Note that the comet will pass the Great Andromeda Galaxy in early April. Created using Cartes du Ciel.
Jupiter with the stars of winter in a moon brightened sky at 9:30 p.m. March 27, 2013. Created using Stellarium.
Saturn near Spica and the moon at 6 a.m. on March 28th. The moon will be passing Saturn on Friday afternoon, below the horizon. Created using Stellarium.
03/26/2013 – Ephemeris – The universe is slightly older than we thought
Ephemeris for Tuesday, March 26th. The sun will rise at 7:34. It’ll be up for 12 hours and 28 minutes, setting at 8:02. The moon, 1 day before full, will set at 7:20 tomorrow morning.
Last week NASA and the European Space Agency announced the findings from the Planck satellite. Along with a sharper map of the Cosmic Microwave Background, created at the moment the Universe became transparent some 380,000 years after the Big Bang, Planck data revealed a slightly older universe of 13.82 billion years. This is with the error thought to be in the last measurement. So it’s a refinement. Also the universe appears to be expanding at a slightly lower rate that had been. Of the three main constituents of the universe, ordinary matter out of which you, me and the stars are made of is 4.9 percent, dark matter that holds galaxy clusters together is at 26 percent, while dark energy is at 68.3 percent, a decrease for it.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Cosmic Microwave Background as determined by the Planck satellite. Image credit: ESA and the Planck Collaboration.
03/25/2013 – Ephemeris – What are comets made of?
Ephemeris for Monday, March 25th. The sun will rise at 7:35. It’ll be up for 12 hours and 25 minutes, setting at 8:01. The moon, 2 days before full, will set at 6:51 tomorrow morning.
For Jews this the first day of Passover, which began at sundown last night. I’ll have more to say about the relationship between Passover and Easter, and the astronomical connection later in the week. Comet PanSTARRS is definitely heading away from us now, about 116 million miles Its distance from the sun is now 51 million miles, between Mercury and Venus’s distance from the sun.. Our modern understanding of comets comes from the mid 20th century when Fred Whipple proposed that comets were composed of frozen gasses and dust and small particles of minerals. This has led to the popular description that comets are dirty snowballs. This described the nucleus of the comet, tiny compared to its head or coma.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
03/22/2013 – Ephameris – Comet PanSTARRS: Ancient and not so ancient fears of comets
Ephemeris for Friday, March 22nd. The sun will rise at 7:41. It’ll be up for 12 hours and 16 minutes, setting at 7:57. The moon, 3 days past first quarter, will set at 5:24 tomorrow morning.
Comet PanSTARRS is moving northward and away from the sun. It is slowly being seen higher in the west northwest when first spotted. The head of PanSTARRS’ brightness should be down to 3rd magnitude, as bright as the star in the Big Dipper that connects the handle to the bowl. Comets, in ancient times, were thought to be omens of the death of kings, famines and the such. Ancient astronomers and astrologers. were used to the motions of the planets, though they never really understood them, they could model the motions with varying degrees of accuracy. Comets were the wild cards, disrupting the plan of the gods, and so were considered bad news. Western astronomers from Aristotle up to Kepler thought they were atmospheric phenomena.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet PanSTARRS about an hour and a quarter after sunset for March 22 through the 25th. Created using Stellarium and Cartes du Ciel. Click on the image to enlarge.
Comets were thought to be bad news:
The comet of 1857
Comets as daggers or swords. Bad news? You bet.
Comet leaves destruction in its wake. A woodcut.
03/21/2013 – Ephemeris – Where did Comet PanSTARRS come from?
Ephemeris for Thursday, March 21st. The sun will rise at 7:43. It’ll be up for 12 hours and 13 minutes, setting at 7:56. The moon, 2 days past first quarter, will set at 4:52 tomorrow morning.
Comet PanSTARRS is heading away from both the sun and the earth. It heading northward. Its orbit is inclined nearly 90 degrees away from the plane of the earth’s orbit. PanSTARRS will recede far past Neptune or the Kuiper Belt of objects that include the dwarf planet Pluto into the Oort cloud of cometary objects that extend out to a light year or 6 trillion miles from the sun. This cloud was named after Dutch astronomer Jan Oort. The comet may be ejected from the solar system. It’s orbit is currently calculated to be slightly hyperbolic. If that holds up, it will drift among the stars. It is thought that occasionally, in millions of years a star comes close or through the Oort cloud and scatters them.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Artist’s impression of the Oort Cloud. (NASA/JPL). Hat Tip: Universe Today.
Comet PanSTARRS in the next 5 days at 9:15 p.m. Created using Stellarium and Cartes du Ciel.
03/20/2013 – Ephemeris – When does spring start, and where is Comet PanSTARRS and the bright planets this week?
Ephemeris for Wednesday, March 20th. The sun will rise at 7:45. It’ll be up for 12 hours and 10 minutes, setting at 7:55. The moon, 1 day past first quarter, will set at 4:17 tomorrow morning.
The sun will cross the earth equator shortly at 7:02 a.m. bringing the season of spring. It’s the vernal equinox. Comet PanSTARRS is in the west northwest low on the horizon. It can best be seen about 9:15 or so. It will set at 9:52 p.m. Jupiter is located in the constellation of Taurus and is in the high southwest during the evening. It will set at 2:00 a.m. Jupiter is a wonderful sight in telescopes with its cloud bands and its moons which change positions each night. The other bright planet Saturn will rise at 11:12 p.m. in the east southeast. It’s located in eastern Virgo. Saturn will pass due south at 4:24 a.m. Saturn is the most beautiful of planets when seen in telescopes. It will be in the southwest for early risers.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet PanSTARRS in the next 5 days at 9:15 p.m. Created using Stellarium and Cartes du Ciel.
Jupiter, the moon and winter stars at 10 p.m. on March 20, 2013. Created using Stellarium.
Saturn and the morning stars at 6 a.m. on March 21, 2013. Created using Stellarium.
03/19/2013 – Ephemeris – PanSTARRS, of course, plus a spring preview
Ephemeris for Tuesday, March 19th. The sun will rise at 7:47. It’ll be up for 12 hours and 6 minutes, setting at 7:53. The moon, at first quarter today, will set at 3:38 tomorrow morning.
Comet PanSTARRS continues to be seen low in evening twilight. It is moving now into the west northwest. When it becomes dark enough it will display a fan shaped tail in binoculars. It is moving away from both the sun and the earth. Tomorrow will see our own milestone as the earth moves into a position where the sun appears over the earth’s equator, and the sun sets at the south pole of the earth and rises at the north pole. It will be the vernal or spring equinox. Australians and other folks south of the equator may prefer to call it the March equinox, because for them autumn starts. The exact time the sun will appear to cross the equator heading northward will be 7:02 tomorrow morning. The sun will keep heading northward until June 21st.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Comet PanSTARRS for this week’s weekdays at 9:15 p.m. Created using Stellarium and Cartes du Ciel.
The earth as seen from the sun near the vernal equinox. See the earth from north pole to south pole. Created using Celestia.
03/18/2013 – Ephemeris – Comet PanSTARRS, the view from Stereo B
Ephemeris for Monday, March 18th. The sun will rise at 7:48. It’ll be up for 12 hours and 3 minutes, setting at 7:52. The moon, 1 day before first quarter, will set at 2:54 tomorrow morning.
Comet PanSTARRS is now a prominent part of our twilight after sunset. It should be visible from maybe 8:40 until 9:41 p.m. when it sets, clear skies and a low horizon willing. Photographs are coming in from all over, including a time lapse movie from the satellite Stereo B, which is now nearly behind the sun looking back at the comet and the earth in the background. The dust tail of the comet was being ejected in sheets, possibly due to the rotation of the comet’s nucleus. Comets generally eject gas and dust from one of more hot spots. When rotated toward the sun they become active and begin to spew gas and dust. When rotated away, they become quiet once again. It looks like Comet PanSTARRS is matching its original brightness estimates.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The video from Stereo B can be found here:
and here:
http://stereo.gsfc.nasa.gov/gallery/item.php?id=selects&iid=182
Comet PanSTARRS in the next 5 days at 9:15 p.m. Created using Stellarium and Cartes du Ciel.
Bob Moler's Ephemeris Blog 