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11/12/2015 – Ephemeris – The North Taurid meteor shower
Ephemeris for Thursday, November 12th. The Sun will rise at 7:35. It’ll be up for 9 hours and 42 minutes, setting at 5:18. The Moon, 1 day past new, will set at 6:19 this evening.
Today is the expected peak of the Northern Taurid meteor shower. While poor in numbers, the two Taurid showers produce many fireballs, that are really, really bright. So bright they are not hindered by a bright moon. They will be visible all night because the radiant, near the head of Taurus the bull will rise in the east by the end of twilight. The radiant is below the Pleiades star cluster and just above the letter V group of stars that is the head of the bull. The path of Encke’s comet, which is responsible, crosses near the Earth’s orbit twice a year. Now and where the Earth is on June 30th. Those meteors then would seem to come from out of the Sun, leaving some to speculate that the Tunguska event in 1908 was caused by a piece of Encke’s Comet.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Taurid Radiant
It turns out that Earth isn’t the only planet to have a meteor shower from Encke’s Comet. It happens to be Mercury. Dave Dickinson has a post on Universe Today pointing to an announcement of data returned from the MESSENGER spacecraft that orbited Mercury at the Division of Planetary Sciences of the American Astronomical Society (#DPS15) meeting this week.
05/07/2015 – Ephemeris – Mercury is at greatest eastern elongation today
Ephemeris for Thursday, May 7th. Today the Sun will be up for 14 hours and 30 minutes, setting at 8:54. The Moon, half way from full to last quarter, will rise at 12:20 tomorrow morning. Tomorrow the Sun will rise at 6:23.
The tiny planet Mercury has been in the news lately because the MESSENGER spacecraft plunged onto its surface a week ago, after having mapped and studied chemical composition of this planet for four years. Today, for Mercury watchers from the Earth, it reached its greatest angular separation from the sun in its orbit, of 21 degrees just before 1 a.m. Mercury has always been a tough planet to study, low to the horizon in twilight. It’s also a tough planet to get to with a spacecraft, being far down the Sun’s gravity well. MESSENGER took 7 years to get there, bleeding off energy by passing Earth, Venus and Mercury itself to fall into orbit of this little world that was full of surprises.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Mercury’s orbit as seen from about 45 degrees north latitude Earth at the greatest eastern elongation at sunset on May 7, 2015. Created using Stellarium.
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The other red line is the plane of the Earth’s orbit. In the spring at sunset it is much closer to vertical than in autumn. The angle of the ecliptic to the horizon at sunset on the vernal equinox is 90° – (your latitude) + 23.5°. Here near 45° north latitude it’s 68.5°. For the sunset at the autumnal equinox the formula is 90° – (your latitude) – 23.5° or 21.5°. The ecliptic will really lay down making planets close to the direction of the Sun hard to spot. In the morning sky the ecliptic will be steep at the autumnal equinox and lay down at the vernal equinox. Thus the best time to spot Mercury, which never strays far from the sun is on late winter and spring evenings and late summer and autumn mornings. Also note that Mercury’s 7 degree inclination to the ecliptic helps it now.
Also note that we are seeing Mercury’s orbit nearly edge on. It will be edge-on in a couple of days. It so happens that a year from now, the morning of May 9th, 2016, for us in the United States, Mercury will transit, or cross in front of, the Sun. Three years ago this June we witnessed the extremely rare transit of Venus. The transit of Mercury isn’t as spectacular or rare, but it’s rare enough.
05/04/2015 – Ephemeris – Last good evening appearance of Mercury for the year*
Note: This program was recorded before the MESSENGER spacecraft crashed into Mercury.
Ephemeris for Monday, May 4th. Today the Sun will be up for 14 hours and 22 minutes, setting at 8:51. The Moon, 1 day past full, will rise at 9:29 this evening. Tomorrow the Sun will rise at 6:27.
The tiny and elusive planet Mercury will be making its final easily observable evening appearance of the year. For the next week or so. Not that Mercury is ever easy to spot. The MESSENGER spacecraft, which has been orbiting Mercury for the past four years is out of fuel and is descending to an impact any day now. It may already have. Mercury is the smallest planet only 50% larger than the diameter of our Moon. There are two planetary satellites larger than it: Jupiter’s Ganymede and Saturn’s Titan. It is a whole lot larger than Pluto, which was demoted to dwarf planet 9 years ago. Mercury is the second densest planet after the Earth. And even Venus with its greenhouse effect is hotter.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
*For northern hemisphere viewers.
Addendum
Mercury, Venus and the setting stars of winter at 10 p.m., May 4, 2015. Created using Stellarium.
Four views of Mercury with colors based on the mineralogy seen. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. Click on image to enlarge.
Here’s your chance to name some craters on Mercury
Here’s a message from Heather Weir at NASA’s Goddard Space Center:
“TO HONOR THE ASTOUNDING ACHIEVEMENTS OF THE MESSENGER MISSION, THERE WILL BE AN INTERNATIONAL COMPETITION TO NAME A CRATER ON MERCURY!
“OPENS DECEMBER 15, 2014 (00:00 UTC) CLOSES JANUARY 15, 2015 (11:59 UTC)
“The MESSENGER Team is seeking help from all Earthlings to suggest names for five impact craters on Mercury. This is a chance to immortalize an important person in the Arts and Humanities from any nation or cultural group by having a crater on the planet Mercury named in their honor! We will accept submissions beginning midnight (00:00 UTC) December 15, 2014 until January 15, 2015 (23:59 UTC). All entries will be reviewed by Team representatives and expert panels. Then, 15 finalist names will be submitted to the International Astronomical Union (IAU) for selection of the 5 winners. Winning submissions will be announced by the IAU to coincide with MESSENGER’s End of Mission Operations in late March/April 2015. Full details are available on the MESSENGER web site http://namecraters.carnegiescience.edu/.”
As the MESSENGER mission to orbit and study the solar system’s innermost planet Mercury is coming to an end when the spacecraft runs out of fuel in a few more months, the MESSENGER team has selected five small but important craters that need names.
The link above will provide all the information needed to enter including rules, pictures, descriptions of the craters to be named and a list of craters already named.
The official naming rules for craters are these: “Deceased artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field and have been recognized as art historically significant figures for more than 50 years.”
Tip of the old astronomer’s observing cap to the NASA/JPL Solar System Ambassadors.Program.
12/29/11 – Ephemeris – Astronomical highlights from 2011
Thursday, December 29th. The sun will rise at 8:18. It’ll be up for 8 hours and 51 minutes, setting at 5:10. The moon, 3 days before first quarter, will set at 11:00 this evening.
Let’s look at the best astronomical events of 2011. To my mind Comet Lovejoy’s survival near the sun is one. The announcements from the Kepler satellite keep coming in. Over 2000 planets in other solar systems suspected including a planet 2.4 times the size of the earth in its star’s habitable zone, two planets of another star about the size of the earth and a planet with two suns. A fourth moon of Pluto was discovered, worrying scientists operating the New Horizons spacecraft that will reach Pluto in 3 and a half years that there may be a debris field around the dwarf planet. This year the MESSENGER satellite gained orbit of the innermost planet Mercury, and the Dawn spacecraft began orbiting the asteroid Vesta. Those are just a sample.
* Times, as always are for the Traverse City/Interlochen area of Michigan.
03/17/11 – Ephemeris – MESSENGER spacecraft arrives at Mercury tonight
Ephemeris for St. Patrick’s Day, Thursday, March 17th. The sun will rise at 7:51. It’ll be up for 11 hours and 59 minutes, setting at 7:50. The moon, 2 days before full, will set at 6:48 tomorrow morning.
This evening the MESSENGER Spacecraft will fire its main engine for 15 minutes to put itself in orbit of the planet Mercury. The rocket firing will be at 8:45 this evening. Due to light time delays caused by Mercury being 97 million miles away, we won’t know if the rocket fired until 8:54. While its high gain antenna won’t be pointed at earth, we should get a signal from its omni- directional antenna. We did get a signal from Cassini with its orbital insertion of Saturn in 2004, and that was nearly a billion miles away. I don’t know if NASA TV’s covering the insertion live, but Johns Hopkins Applied Physics Laboratory is having a live webcast. Google “messenger mercury live orbital insertion” It was the first hit. I’ll have the address on the blog. http://messenger.jhuapl.edu/mer_orbit.html
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
What we used to know about Mercury
On Thursday evening, 8:45 p.m. March 17 EDT (12:45 a.m. March 18 UTC) the MESSENGER spacecraft will complete the second of NASA’s 2011 planetary trifecta when it will, if all goes well, fire its rocket engine to drop into orbit of the tiny planet Mercury. We’ve had six quick peeks at Mercury so far. Three by the Mariner 10 spacecraft in the 1970’s which looked at the same half of the planet due to Mercury’s unique rotational period. And three more by MESSENGER as it used Mercury to put on the breaks, so it would be going slow enough this time, so it’s rocket engine could drop it into polar orbit of the planet.
At first blush, Mercury looks like the moon. But it’s not. The moon is light, being made up, apparently, of mostly the crustal materials expelled by the earth and another Mars sized body. So it has a relatively small core. Mercury, on the other hand has a large core, and is the second densest planet at 5.43 grams per cubic centimeter. It’s only beaten out by the earth’s 5.52 g/cm3.
We’re going to learn a lot more about Mercury in the next year or so as MESSENGER maps Mercury and the complex interaction between it and the solar wind and magnetic field coming from the sun. Lets look back at the early history of our knowledge of Mercury.
It seems the that early Greeks noticed this elusive planet. They saw it in the morning sometimes, and then they saw it in the evening. At first they thought it was two separate planets that they gave the name Hermes in the evening and Apollo in the morning before they figured out that it was the same planet. The name Mercury we know the planet by today is the Roman equivalent of Hermes.
Another revelation came later. In my youth Mercury was thought to be in tidal lock with the sun, like our moon is to the earth. The rather poor markings found on the planet seen low in the sky at dusk and dawn seemed to bear that out an 88 day rotation to match its 88 day revolution of the sun. It wasn’t until 1965 that radar observations proved that the rotation was 2/3 of 88 days. Every 2 orbits of the sun Mercury rotates 3 times. It seems that the best times to spot Mercury are when it’s in the same part of its orbit, but basically every other return to that spot. Funny thing. The northern hemisphere’s best views of Mercury are for its eastern elongation on spring evenings and western elongations on autumn mornings. In effect we’re viewing Mercury at the same point in its orbit, when it is near its perihelion, when it is closest to the sun. The southern hemispheric observers get to see more favorable views of Mercury, when it’s farthest from the sun.
As we’ve found with all the planets that we’ve gotten a close look at, the generalities of our long-standing ignorance is brushed away. Each planet is its own unique place in the sun.
Taken from my March, 2011 article in the Stellar Sentinel,the newsletter of the Grand Traverse Astronomical Society.
Here is the MESSENGER web page. This mission is run for NASA by the Johns Hopkins Applied Physics Laboratory.
MESSENGER’s First Look at Mercury’s Previously Unseen Side
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Bob Moler's Ephemeris Blog 