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06/18/2015 – Ephemeris – 26 days to Pluto!
Ephemeris for Thursday, June 18th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31. The Moon, 2 days past new, will set at 10:57 this evening. Tomorrow the Sun will rise at 5:56.
I hope everyone’s been following the progress of the New Horizons spacecraft as it nears the Pluto system. It will reach and pass through the Pluto system on July 14th, only 26 days from now after a journey of 9 years. Now, Pluto is more than a dot in the probe’s cameras, which are used to look for possible hazardous rings of debris, more moons and for navigational purposes. New Horizons is aimed for a window less than a hundred miles on a side, and a few minutes in time. All its moves to study Pluto and its moons have been pre-programmed in and actually tested two years ago to make sure everything works. We will not hear from the spacecraft on encounter day, it will be too busy.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Artist conception of the New Horizons spacecraft at Pluto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
New Horizon’s trajectory through the solar system. Credit: NASA/APL.
New Horizons Encounter Timeline. Credit: NASA/JHAPL.
New Horizons at closest approach to Pluto. Credit: NASA/JHAPL.
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.
04/24/2015 – Ephemeris – The Dawn spacecraft is descending to dwarf planet Ceres’ day side
Ephemeris for Arbor Day, Friday, April 24th. Today the Sun will be up for 13 hours and 54 minutes, setting at 8:38. The Moon, 1 day before first quarter, will set at 2:26 tomorrow morning. Tomorrow the Sun will rise at 6:42.
The Dawn spacecraft with its ion engine is descending into orbit of that other dwarf planet Ceres, the largest body in the asteroid belt. Over the past month Dawn has been maneuvering over Ceres’ night side to descend into a polar orbit to better survey the planet. Last week the Jet Propulsion Laboratory team that has been operating the spacecraft released a video of several photographs of Ceres’ pole as it rotated. It was still a crescent view, but soon we’ll see Ceres up close and very personal. We’ll get a closer look at those enigmatic white spots. Are they just white ice patches on the surface, or are they ice cryovolcanoes spewing water, or something else? Stay tuned.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Ceres animation from April 14-15, 2015. Dawn was 14,000 miles (22,000 km) from Ceres. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. Click the image to enlarge.
This is a newer animation than the one mentioned in the transcript above that was actually written on the 19th. Here’s a link to the NASA page that describes the image. It also has a link to an enlarged frame containing the double bright spot.
This is a processed still image of Ceres from the above animated sequence of images.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
There’s no help figuring out what they are but the smaller spot is resolved into two spots. The bright one is still unresolved. As of yesterday the Dawn spacecraft should be in its first circular orbit of Ceres at an altitude of 8,400 miles (13,500 km) from Ceres for a few weeks before descending to a lower orbit of Ceres the starting the first week in May.
04/23/2015 – Ephemeris – New Horizons’ first glimpse of Pluto and Charon in color
Ephemeris for Thursday, April 23rd. Today the Sun will be up for 13 hours and 52 minutes, setting at 8:37. The Moon, 2 days before first quarter, will set at 1:44 tomorrow morning. Tomorrow the Sun will rise at 6:43.
Last week NASA’s New Horizons team running the spacecraft that’s been in flight to the dwarf planet Pluto released their first color of Pluto and it’s moon Charon. The photo doesn’t show any surface features. That’s to come in the next month or two. However, Pluto shows kind of a pale orange-pink color, hinting of the colorful images to come. Charon is a dull gray like the dwarf planet Ceres, which Dawn is approaching, and our own Moon. How could two bodies with a common origin appear so different? Stay tuned. New Horizons will pass through the Pluto system in a couple of hours on July 14th, but will send back the mother lode of its data over the next 16 months.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
First color picture of Pluto and its moon Charon taken by the New Horizons spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. Click to enlarge.
From the NASA website:
“This image of Pluto and its largest moon, Charon, was taken by the Ralph color imager aboard NASA’s New Horizons spacecraft on April 9 and downlinked to Earth the following day. It is the first color image ever made of the Pluto system by a spacecraft on approach. The image is a preliminary reconstruction, which will be refined later by the New Horizons science team. Clearly visible are both Pluto and the Texas-sized Charon. The image was made from a distance of about 71 million miles (115 million kilometers)—roughly the distance from the Sun to Venus. At this distance, neither Pluto nor Charon is well resolved by the color imager, but their distinctly different appearances can be seen. As New Horizons approaches its flyby of Pluto on July 14, it will deliver color images that eventually show surface features as small as a few miles across.”
03/03/2015 – Ephemeris – The bright spots on Ceres are still a mystery
Ephemeris for Tuesday, March 3rd. The Sun will rise at 7:17. It’ll be up for 11 hours and 15 minutes, setting at 6:32. The Moon, 2 days before full, will set at 6:30 tomorrow morning.
The Dawn spacecraft is approaching the asteroid Ceres. It will be gently captured by Ceres on the 6th. This as an update from the date I gave you yesterday. Then the spacecraft will spiral closer and closer to the asteroid over the next few months. There is a mystery spot on Ceres, a bright spot that was visible by the Hubble Space Telescope orbiting Earth. As Dawn got close enough to resolve Ceres it too saw the bright spot. As the spacecraft got even closer the spot showed to be smaller and smaller. I thought it might be a crater that penetrated into Ceres icy interior. But the latest image, taken February 19th shows that the bright spot has a companion spot, both inside a crater and still too small to resolve. It’s still a mystery.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Hubble’s best photo of Ceres. Note the white spot near the top of the image. Image Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI)
The white spot shows as Dawn approaches Ceres. Credit: NASA/JPL.
The bright spot is two. Picture taken February 19, 2015 from 29,000 miles (46,700 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
This photo will be the best photo of the bright spots until the end of April, an Dawn maneuvers over the night side of Ceres.
On March 2nd NASA held a Dawn Mission Pre- Close Approach News Briefing which can be found on YouTube.
03/02/2015 – Ephemeris – The Dawn spacecraft (The turtle wins the race)
Ephemeris for Monday, March 2nd. The sun will rise at 7:19. It’ll be up for 11 hours and 12 minutes, setting at 6:31. The moon, 3 days before full, will set at 6:00 tomorrow morning.
On Thursday March 5th NASA’s Dawn spacecraft will fall under the gravitational influence of the asteroid, or actually recently promoted dwarf planet Ceres and enter orbit. The journey took 7 years including an intermediate year-long stop at the asteroid Vesta. Dawn uses the latest in ion thrusters, or latest when it was launched. Using power generated by its solar panels it ejects xenon ions from one of its three ion thrusters to produce a thrust comparable to the weight of a piece of paper. It can accelerate the spacecraft from zero to 60 miles per hour in a few days. In the tale of the hare and the tortoise it’s in the tortoise class, at least to start. Ion engines are 10 times as efficient as chemical rockets and they can thrust for years.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Artist’s rendition of the Dawn spacecraft at Vesta. Credit: NASA/JPL
Ion engine test. Xenon ions glow blue. Credit NASA.
02/23/2015 – Ephemeris – The Launch of the DSCOVR satellite
Ephemeris for Monday, February 23rd. The sun will rise at 7:30. It’ll be up for 10 hours and 51 minutes, setting at 6:22. The moon, 2 days before first quarter, will set at 12:24 tomorrow morning.
On Wednesday the 11th the DSCOVR satellite was launched to a special point between the Earth and the Sun called the Lagrangian point 1 or the Earth-Sun L1 point. It’s a point of gravitational equilibrium between the Earth and the Sun, about a million miles sun-ward of the Earth, or four times the distance of the Moon. It will take the craft over 100 days to get there, which it will slowly orbit. It will act as an early warning sentinel, replacing the aging ACE spacecraft. It will give us about an hour’s warning of incoming coronal mass ejections or CMEs erupting from the Sun. It also has an earth pointing camera with various filters pointed to the full earth and occasionally the far side of the new Moon.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
SpaceX Falcon 9 V1.1 first stage burns to launch DSCOVR to the Earth-Sun L1 point. Credit: NASA. Click to enlarge.
Click to enlarge
Earth-Sun Lagrangian Points. Source: Wikimedia Commons, Xander89. Click to enlarge.
12/26/2014 – Ephemeris – Tragedies and triumphs of 2014
Ephemeris for Friday, December 26th. The sun will rise at 8:18. It’ll be up for 8 hours and 49 minutes, setting at 5:08. The moon, 2 days before first quarter, will set at 11:02 this evening.
2014 was a year of personal tragedy and also tragedy and triumph in space. The Space tragedies came in October with the destruction and loss of Orbital Science’s third supply mission to the International Space Station when the their Antares rocket blew up right after launch. A few days later Virgin Galactic’s SpaceShipTwo disintegrated on a test flight killing a pilot. In the Triumph department the European Space Agency’s Rosetta caught up and orbited its comet 67P, for short, in August and bounced down its lander Philae in November. It wasn’t supposed to bounce, but stick the landing. Bruised and battered Philae delivered its science before its batteries died. And this month an unmanned Orion capsule made its maiden voyage into space.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orbital Sciences Antares rocket explodes seconds after liftoff on October 28, 2014. Credit NASA.
SpaceShipTwo disintegrates October 31, 2014 killing a pilot. Credit USA Today.
After a second bounce on the Comet 67P the Philae lander ended up sideways apparently on the base of a cliff. Researchers were able to get data from just about all the instruments before the battery discharged. The team hopes and the comet gets closer to the sun and the sun angle changes they can revive Philae. Credit: ESA.
Screen capture of Delta IV Heavy rocket liftoff carrying the Orion test article into orbit on December 4, 2014. Credit .NASA via BBC
Ride back to the earth with Orion via a camera mounted in a window. The window is facing aft as the capsule re-enters the atmosphere heat shield first at 20,000 miles per hour. You’ll experience everything except the G forces. It comes with appropriate spacey music. It’s as close as I’ll ever get to ride in one of these things.
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.
Bob Moler's Ephemeris Blog 