03/05/2015 – Ephemeris – Tonight’s moon is the smallest full moon of the year

March 5, 2015 Leave a comment

Ephemeris for Thursday, March 5th.  The Sun will rise at 7:13.  It’ll be up for 11 hours and 21 minutes, setting at 6:35.   The Moon, at full today, will rise at 6:48 this evening.

We’ve heard all about the supermoon, when the moon is at its closest.  This is supposedly best seen when the full moon is rising.  Of course the rising moon or sun, or the setting of these bodies look larger than normal due to an optical illusion.  Well tonight’s full moon is the opposite.  The Moon is at apogee, which is the farthest it gets in its orbit of the Earth.  It’s 253 thousand miles (406 thousand km) from Earth.  So the Moon should be, let me see, a mini-moon?  So the Moon should appear small as it rises tonight.  So if it’s clear tonight you might check out the moon.  Does it appear as large as it usually does?  Or does it appear smaller?  The moon, being alone in the sky lacks anything else to compare its size to.  It makes estimations difficult.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Mini and supermoon comparison

Here are the full mini and supermoons of the year. Created using Cartes du Ceil (Sky Charts)

Categories: Ephemeris Program, The Moon Tags:

03/04/2015 – Ephemeris – Our weekly look at the bright planets

March 4, 2015 Leave a comment

Ephemeris for Wednesday, March 4th.  The Sun will rise at 7:15.  It’ll be up for 11 hours and 18 minutes, setting at 6:34.   The Moon, 1 day before full, will set at 6:59 tomorrow morning.

Lets take a look at the bright planets for this week.  Brilliant Venus is in the west by 7:30 p.m. It will set at 9:13 p.m.  It’s separating from Mars which appears below and right of it.  The Red Planet will set tonight at 8:47 p.m.  Jupiter will appear In the southeastern sky in the evening.  It will be up just about all night, and will set at 6:16 a.m.  It’s near the sickle-shaped head of Leo the lion, and it’s the brightest star-like object in the sky.  In telescopes tonight the moon Io will be behind Jupiter and will pop into sunlight a bit away from the planet at 9:39 p.m.  Tomorrow night the 5th the moon Europa will duck behind Jupiter at 8:48 p.m.  After that only 3 of the moons will be visible, until 12:57 a.m. when Europa will appear on the other side.*  Early risers will be able to spot Saturn which will rise in the east-southeast at 1:25 a.m.   It’s in the south at 6 a.m.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

* Due to a date mix up the radio program may be incorrect.  The occultation of Europa on the 5th being set on the 4th.  The Io occultation is since added.

Addendum

Venus and Mars

Venus and Mars in the west at 7:30 p.m. on March 4, 2015. Created using Stellarium.

Looking south at 9 p.m.

Jupiter, the full Moon and the winter stars at 9 p.m. on March 4, 2014. Created using Stellarium.

Jupiter and its moons

Jupiter and moons at 9:39 p.m., when Io leaves Jupiter’s shadow on March 4, 2015. Created using Cartes du Ceil (Sky Charts).

The Moon

The nearly full moon at 9 p.m. on March 4, 2015. Created using Virtual Moon Atlas.

Saturn & the summer stars

Looking south toward Saturn along with the summer stars and the setting Moon in the west at 6 a.m. March 5, 2015. Created using Stellarium.

Saturn and moons

What Saturn and its moons might appear like in a telescope at 6 a.m., March 5, 2015. Small telescopes will show only the moon Titan. Created using Cartes du Ceil (Sky Charts).

03/03/2015 – Ephemeris – The bright spots on Ceres are still a mystery

March 3, 2015 Leave a comment

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

Ceres from Hubble

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)

White spot from Dawn

The white spot shows as Dawn approaches Ceres. Credit: NASA/JPL.

Ceres 2/19/15

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.

Categories: Asteroid, NASA Tags: , ,

03/02/2015 – Ephemeris – The Dawn spacecraft (The turtle wins the race)

March 2, 2015 Leave a comment

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

Dawn spacecraft at Vesta

Artist’s rendition of the Dawn spacecraft at Vesta. Credit: NASA/JPL

Ion engine test

Ion engine test. Xenon ions glow blue. Credit NASA.

 

02/27/2015 – Ephemeris – Previewing the month of March

February 27, 2015 Comments off

Ephemeris for Friday, February 27th.  The sun will rise at 7:24.  It’ll be up for 11 hours and 3 minutes, setting at 6:27.   The moon, 2 days past first quarter, will set at 4:08 tomorrow morning.

During March the increase in daylight hours are at its greatest, with Spring 3 weeks away.  Daylight hours will increase from 11 hours and 9 minutes Sunday to 12 hours and 42 minutes on the 31st.  Along with that the altitude of the sun at noon will increase from 38 degrees Sunday to 49 ½ degrees at month’s end.  Local noon, by the way for Interlochen and Traverse City is about 12:50 p.m, which is mainly due to the fact that our standard time meridian happens to run through Philadelphia.  That’s before daylight time starts in a bit more than a week.  Then our time meridian will run by the eastern tip of Nova Scotia, so local noon, when the Sun is due south will occur at 1:50 p.m.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

March 2015 star chart

Star Chart for March 2015. Created using my LookingUp program.

The Moon is not plotted.  The planets and stars are plotted for the 15th at 10 p.m. EDT.  That is chart time.

Evening astronomical twilight ends at 8:07 p.m. EST on March 1st, increasing to 9:49 p.m. EDT on the 31st.

Morning astronomical twilight starts at 5:43 a.m. EST on March 1st, and decreasing to 5:45 a.m. EDT on the 31st.  (Yes it is a decrease, thanks to the imposition of daylight time on March 8th)

Add a half hour to the chart time every week before the 15th and subtract and hour for every week after the 15th.

For a list of constellation names to go with the abbreviations click here.

The green pointer from the Big Dipper is:

  • Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
  • Drill a hole in the bowl of the Big Dipper and the water will drip on the back of Leo the Lion.
  • Follow the arc of the Big Dipper’s handle to Arcturus

Calendar of Planetary Events

Credit:  Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC)

To generate your own calendar go to http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html

Times are Eastern Standard Time on a 24 hour clock.  Some additions made to aid clarity.

Conjunctions like the Moon-Saturn: 2.4° S means Saturn will appear 2.4° south of the Moon.

Mar 01 Su Venus: 30.1° E
05 Th 02:35 Moon Apogee: 406,400 km
05 Th 13:05 Full Moon
07 Sa 16:04 Moon Ascending Node
12 Th 04:25 Moon-Saturn: 2.4° S
13 Fr 13:48 Last Quarter
13 Fr 21:39 Moon South Dec.: 18.3° S
19 Th 15:38 Moon Perigee: 357,600 km
20 Fr 05:36 New Moon
20 Fr 05:46 Total Solar Eclipse
  20  Fr 18:45 Vernal Equinox
20 Fr 22:19 Moon Descending Node
21 Sa 18:13 Moon-Mars: 1° N
22 Su 15:51 Moon-Venus: 2.9° N
25 We 02:55 Moon-Aldebaran: 0.9° S
26 Th 10:29 Moon North Dec.: 18.2° N
27 Fr 03:43 First Quarter

02/26/2015 – Ephemeris – The strange month of February

February 26, 2015 Comments off

Ephemeris for Thursday, February 26th.  The sun will rise at 7:25.  It’ll be up for 11 hours and 1 minute, setting at 6:26.   The moon, 1 day past first quarter, will set at 3:21 tomorrow morning.

Let’s take a shot at why February is the shortest month.  Blame the ancient Romans and their poor timekeeping skills.  The Roman calendar was based on the Sun, or rather the seasons, what we would call the tropical year, rather than the Moon.  With a lunar calendar it was easy to tell if it was off by a day or two.  The Romans apparently started with a 12 month calendar starting in March with spring.  Before the calendar reform of 45 BC months had alternating days of 29 and 31 except for February which had 28.  That left them a bit short, so it appears that they added a month Intercalaris every few years or so to fix it.  That eventually came down to adding a day to February every 4 years to fix the problem.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Look quick! A new comet escapes the Sun

February 26, 2015 Comments off

A sun grazing comet was discovered in SOHO chronograph images.  And unlike Comet ISON 15 months ago which checked in but didn’t check out.  This one escaped to possibly become visible in our evening sky.  It was the 2875th comet discovered on SOHO chronograph images.  Usually it ends there, but the comet, now named C/2015 D1 (SOHO).

Comet track

Hot off the press. Comet 2015 D1 was part of the download of comet elements this afternoon. Here’s the track with estimated magnitudes for tonight and the next week. Created using Cartes du Ceil (Sky Charts).

A more comprehensive post from Universe Today is here.

 

Categories: Comet, Observing Tags: , ,
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