AVAILABLE MONTHS

2010:  Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec 

2011:  Jan  Feb  Mar  Apr  May  Jun 


 1.6.x & 1.4.1 LINKS

Throughout this website you will find pairs of links labeled "1.6.x" and "1.4.1".  Click here for a brief explanation.


UTC: CELESTIA'S DISPLAY OF TIME

CELESTIA's clock displays Coordinated Universal Time, UTC.  Click here for a brief explanation.

APPARENT PATHS OF THE PLANETS

Mercury spends much of the month of February "catching up" with Mars and Neptune.  Venus "passes" distant Pluto.

Note: in the 1.6.x and 1.4.1 links in this column below, planets east ("left") of the Sun are visible in your sky after sunset, while planets west ("right") of the Sun are visible before sunrise.

Run the links below as often as you like, and keep an eye on CELESTIA's clock near the top right corner of the program's window.  Don't forget that you can use your keyboard's   J  K   and   L   keys respectively to reverse, slow down and speed up time in CELESTIA.


MERCURY: 2011 Feb

Mercury spends the entire month moving eastward, "catching up" with Mars and Neptune on the 20th.  But all three are so near the Sun that they will be not be visible in its brightness  (1.6.x)   (1.4.1)


VENUS: 2011 Feb

Moving east in Sagittarius, Venus passes distant Pluto before mid-month  (1.6.x)   (1.4.1)


MARS: 2011 Feb

Mars is "overtaken" by the Sun very early in the month near central Capricornus.  It then appears very close to Neptune and Mercury on the 20th  (1.6.x)   (1.4.1)


JUPITER & URANUS: 2011 Feb

Jupiter "distances" itself from slower Uranus all month, and then leaves western Pisces to enter the corner of Cetus before February ends  (1.6.x)   (1.4.1)


SATURN: 2011 Feb

Nearly stationary as February opens, Saturn continues its retrograde motion for the whole month  (1.6.x)   (1.4.1)


NEPTUNE: 2011 Feb

Slow-moving Neptune hugs the border of Capricornus and Aquarius, as the Sun, Mercury and Mars proceed past it  (1.6.x)   (1.4.1)

CELES-TIPS

The following will help you enjoy this page's many links that run events directly in CELESTIA.  If you're new to the program, these tips will also help you learn to use it.

You'll find more information about many of CELESTIA's controls on our  Learning Center  page.


NEW!  ASTRONOMY POSTERS!

This month we proudly present our first "downloadable" astronomy posters!  And more are coming!  If you enjoy posters, you'll love these!  Their impressive detail, sheer beauty and enlightening explanations will make our  Time Zones poster  and  Earth's Tides poster  welcome additions to any collection, classroom, library or office!

THE SUN

APPARENT PATH OF THE SUN: 2011 Feb

Here are the Sun's positions along the Ecliptic at 00:00 UTC on the days shown.

The slightly curved lines above and below the Ecliptic show the extent of the Zodiac, which you may download from our  Bonuses  page and add to any version of CELESTIA.  Note that the curve in the Zodiac lines is the result of CELESTIA's rendering in perspective.

W A R N I N G !     It is never safe to look directly at the real Sun with the naked eye!  Moreover, looking at it through a telescope or binoculars—even for an instant—can cause permanent blindness!  NEVER DO IT!  Consult the professionals at your local planetarium or observatory to learn how you can safely "observe" the Sun and any SOLAR eclipse!

Of course, you can safely view CELESTIA's depiction of the Sun's apparent path in the sky in February.  Here are the links:  (1.6.x)   (1.4.1).  Note that versions 1.6.x and 1.4.1 differ in the way their "follow" and "lock" features work.  If you "follow" Earth and then "lock" the Sun to it, versions 1.6.x and 1.4.1 respectively maintain the "attitudes" of the Ecliptic and the the Celestial Equator.  This means that the Ecliptic remains "level" when you run the first link, but begins to tilt when you run the second!  Differences like this will be discussed on our  Help  page.


HALF OF EARTH IN SUNLIGHT & DARKNESS

During your voyages in CELESTIA, would you like to be able to position yourself directly over the center of the half of Earth in sunlight or the half in darkness at any time this month?  On our  Tips  page, you'll find that it's quite easy to do so!  If you're any kind of sky watcher at all, you probably know just how helpful this can be!

THE MOON

PHASES OF THE MOON: 2011 Feb

In UTC per CELESTIA 1.6.x:
  New: Feb 3, 2:31.  1st Qtr: Feb 11, 7:18.
  Full: Feb 18, 8:36.  Last Qtr: Feb 24, 23:27.
(Celestia 1.4.1 usually indicates respective phase times within about one minute of those in version 1.6.x.)

NOTE: New, 1st Quarter, Full and Last Quarter Moons respectively are defined to occur when the Geocentric Ecliptic Longitudes of the Moon and the Sun differ by 0°, 90°, 180° and 270°.

To watch a short video demonstrating the Phases of the Moon,  click here.

The above diagram is produced with our "Moon Phases Calendar" script.  The numbers of the days of the month were added with an image-editing program.

To watch a short video of our Moon Phases Calendar in action,  click here.


LUNAR APOGEE & PERIGEE: 2011 Feb

Per CELESTIA 1.6.x:
    Apogee: Feb 6, 23:02 UTC; 405,912 km.
    Perigee: Feb 19, 07:22 UTC; 358,273 km.
(Celestia 1.4.1 usually indicates apogee and perigee times within about one minute of those in version 1.6.x.  Both versions of Celestia almost always indicate equal apogee distances and equal perigee distances.)

Determined by our "Earth-Moon Distance" and "Moon's Apparent Path" scripts.  Note that distances given are those between Earth's and the Moon's centers. 


LUNAR ANALEMMA: 2011 Feb

Here is the lunar analemma, generated by the Moon's positions relative to the mean lunar orbit and the Ecliptic at 0:00 UTC every day of February.

This phenomenon can be observed using our "Moon's Apparent Path" script.  The analemma's change of shape month after month begins to give us an idea of just how irregular the lunar orbit is.


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Various astronomical "shadow events" occur throughout the Solar System!  This month's more interesting ones are featured here.

SHADOW WORKS

Here we highlight the most awe-inspiring eclipses taking place in our Solar System.  We also set them up so that all you need to do is click on their links.  Don't forget that you can generate lists of Earth's, Jupiter's, Saturn's, Uranus's, Neptune's and even Pluto's eclipses, using CELESTIA's own built-in "Eclipse Finder."  You'll find it in the program's menu under "Navigation".

Unless noted otherwise, the events identified below are displayed as if viewed from Earth, their magnifications shown in parentheses at the lower right of CELESTIA's window.  Events involving more than one moon are often cyclical, so usually only the first example is given, and then the period of the cycle.

Remember: you can press the   M   key to toggle Moon Labels on and off .


JUPITER

Jupiter is now in that part of its orbit where its equatorial plane, and the orbital planes of the Galileans, are all tilting more and more relative to the Sun.  So fewer eclipses will occur on the largest planet.  In addition, the Galileans are more "spread out" from one another in their orbits this month, so no simultaneous solar eclipses (i.e. involving more than one major moon) occur.

Nonetheless, there are times when two or more Galileans are visible near Jupiter.  Here are highlights of the 28 solar eclipses that are spawned by Io, Europa, Ganymede and Callisto this month, while the shadow of Jupiter stretches to the east (left).  Whenever Io and Europa enter the Jovian shadow this month, they do so hidden by Jupiter.  Many times they can be seen as they emerge from Jupiter's shadow.

With this Galilean info, you can understand why some events involving more than one moon repeat.  It also lets you predict when they may do so again.
Periods:
   Io:  1.769 days
   Europa:  3.551 days
   Ganymede:  7.155 days
   Callisto:  16.69 days
Resonances:
   Io & Europa: 2 to 1
   Io & Ganymede: 4 to 1
   Europa & Ganymede: 2 to 1


SATURN

Like Jupiter, Saturn is now in that part of its orbit where its equatorial plane, as well as the orbital planes of its major equatorial moons, are all tilting more and more relative to the Sun.  So fewer and fewer eclipses will occur on the ringed planet for some time. 

While CELESTIA 1.6.x shows the shadows of Titan, Rhea, Iapetus, Dione and Tethys, version 1.4.1 displays only the shadows of Titan, Rhea & Iapetus.  So, 1.6.x and 1.4.1 respectively show 25 and no solar eclipses on Saturn in February.  In addition, version 1.6.x reveals no two moons producing simultaneous solar eclipses this month.

To aid in your viewing, here are the periods of Saturn's major moons.  These do not exhibit the resonances that Jupiter's Galileans display.  Still, you can use this info to predict subsequent eclipses of a single moon.
   Tethys:  1.888 days
   Dione:  2.737 days
   Rhea:  4.518 days
   Titan:  15.95 days
   Iapetus:  79.33 days


URANUS, NEPTUNE & Dwarf Planet PLUTO

Neither Uranus nor Neptune will experience eclipses for decades.  Dwarf planet Pluto will experience no eclipses by Charon for about a century!


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News: 2011 February

News: