AVAILABLE MONTHS

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

2011:  Jan  Feb  Mar  Apr  May  Jun 

APPARENT PATHS OF THE PLANETS

This month, Saturn continues its retrograde motion.  In the middle of April, Mercury too goes retrograde.

Run these links as often as you like, and keep an eye on CELESTIA's clock at top right.  And remember: you can use the J, K and L keys respectively to reverse, slow down and speed up time in CELESTIA.


MERCURY & VENUS: 2010 Apr

Speedy as always, Mercury and Venus move eastward and precede the Sun out of Pisces, but by mid-April Mercury makes a "U-turn"!  It moves westward in central Aries and then achieves Inferior Conjunction at the end of the month, while Venus continues eastward in Taurus.  (1.6.x)   (1.4.1).


MARS: 2010 Apr

Having completed its retrograde loop last month, Mars continues moving eastward in Cancer throughout April  (1.6.x)   (1.4.1).  Because its orbit is relatively similar in size to Earth's orbit, Mars will not "go retrograde" again until early 2012.

Here again are last month's links that let you see Mars's entire retrograde loop of 2009-2010  (1.6.x)   (1.4.1)


JUPITER, URANUS & NEPTUNE: 2010 Apr

Jupiter continues to move slowly eastward through Aquarius in April, but does not quite make it to Pisces.  Uranus and Neptune move eastward in Pisces and Aquarius respectively, but very slowly.  (1.6.x)   (1.4.1)


SATURN: 2010 Apr

Slow-moving, distant Saturn continues its retrograde motion in Virgo throughout the entire month of April.  The gibbous Moon, passing in the last week of the month, is the only other major Solar System object that we see near Saturn throughout April  (1.6.x)   (1.4.1)

Here again are last month's links that let you see Saturn's entire (though smallish) retrograde loop of 2010  (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.


THE SUN

APPARENT PATH OF THE SUN: 2010 Apr

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 April.  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: 2010 Apr

In UTC per CELESTIA 1.6.x (& 1.4.1):
  3rd Qtr: Apr 6, 9:37 (9:38). New: Apr 14, 12:29 (12:30).
  1st Qtr: Apr 21, 18:20 (18:21). Full: Apr 28, 12:19 (12:20).

NOTE: New, 1st Quarter, Full and 3rd 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°.

Produced with our "Moon Phase Calendar" script.  The numbers of the days of the month were added with an image-editing program.


LUNAR PERIGEE & APOGEE: 2010 Apr

Per CELESTIA 1.6.x (and 1.4.1):
    Apogee: Apr 9 2:45 (2:46) UTC; 405,008 km.
    Perigee: Apr 24 21:04 (21:05) UTC; 367,148 km.
Determined by our "Earth-Moon Distance" and "Moon's Apparent Path" scripts.  Note that distances given are the distances between Earth's and the Moon's centers.


LUNAR ANALEMMA: 2010 Apr

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 April.

This phenomenon can be observed using our "Moon's Apparent Path" script.  Compared to the previous three months, the lunar analemma now appears to be widening into a clockwise oval.  Its 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 (and set up) the most awe-inspiring eclipses taking place in our Solar System, 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".

All events listed 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.


JUPITER

As depicted in CELESTIA, here are highlights of the 30 solar eclipses that Io, Europa, Ganymede and Callisto—the "Galilean" moons of Jupiter—produce in April.  You'll see simultaneous solar eclipses this month, as two Galileans cast their shadows on Jupiter at the same time.  As always, examples of the Galilean moons moving into Jupiter's shadow are also included.


SATURN

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 36 and 7 solar eclipses on Saturn in April.  The highlights are as follows:


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: 2010 April

News: