Category: Astronomy

2019, May 19-21: Moon Passes Jupiter

As Jupiter approaches opposition, the event when our planet Earth is between Jupiter and the sun.  Jupiter and the sun are in opposite sides of the sky.  Jupiter rises when the sun sets and Jupiter sets when the sun rises.  Jupiter is in the south at midnight, when the sun is in the south at noon.

A few weeks before opposition, Jupiter appears in the evening and the morning sky.  Here’s what’s to see depending on when you step outside to see it.

Evening

  • May 19: At 10:30 p.m. CDT, the moon, 15.2 days past its New phase and 98% illuminated, is nearly 7° to the upper right of Jupiter and almost 9° to the left of Antares in the southeastern sky.

  • May 20: At 11 p.m. CDT, the moon, 16.2 days old and 94% illuminated, is nearly 7° up in the southeast and 6.5° to the lower left of Jupiter.

Morning

By morning , the moon appears in the southwest.

  • May 20:  At the beginning of morning twilight (about 4 a.m. CDT), the moon, 15.4 days old and 98% illuminated, is 4.6° to the right of Jupiter.  The Giant planet is 24° up in the south-southwest.

  • May 21:  At the beginning of morning twilight, the moon, 16.5 days old and 93% illuminated, is 25° up in the south and 8.2° to the left of Jupiter.

 

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2019, May 17: Moon in Clasp of the Pincers

On Friday evening (May 17), look toward the southeast for a nearly full moon.  The moon appears between Zubenelgenubi and Zubeneschamali, the northern claw and the southern claw, respectively.  The stars are not overly bright, and the moon’s size is exaggerated in the image above.

Today the stars are the two brightest in Libra, the Scales.  This constellation is the only inanimate object in the zodiac, the constellations that the sun, moon, and planets appear to move through.

The two stars were once part of Scorpius, the Scorpion, that is now rising in the southeast below the moon.  The scorpion was divided into two constellations, but the two stars retained their original names.

So if you imagine that the scorpion is largely below the southeast horizon with its pincers up in the sky holding the moon on this evening.

2019, May 15-16: Moon Passes Spica

Step outside as the sky darkens on Wed (May 15) and Thurs (May 26).  The moon appears to pass the bluish star Spica on the two evenings.  Spica is the brightest star in the constellation Virgo.

On May 15, the moon, 11.1 days past its New phase and 90% illuminated, appears 8° above Spica.

On the next evening, the moon, one day older and 92% illuminated, is over 11° to the left of Spica.

Across these two evenings you can see the moon’s eastward movement compared to the starry background.

We notice several changes in the moon:

  • Phase:  The illuminated portion of the moon changes slightly each night, dramatically across a week.
  • Daily Rising and Setting:  On a warm spring evening, notice the moon’s position, relative to nearby trees and houses, for an hour.  You see it get farther west during that time.  Like the sun, it rises in the eastern sky, sometimes southeast and sometimes northeast, and sets later somewhere in the west that mirrors its rising spot.
  • Daily eastward orbital motion:  Each day, the moon moves slightly to the east.  In about 27 days appears near Spica again, but its phase is not quite the same as on these two nights.

2019: May 11-13: Moon and Leo in Evening Sky

Leo, the Lion, stands high in the southwest as the sky darkens in early to mid-May.  The shape is fairly easy to locate.  Six stars resemble a backwards question mark, also known as “The Sickle” for the farm implement.  A triangle trails farther east.  Regulus is the bottom star of the question mark and represents the lion’s heart.  Denebola marks the lion’s tail.  The celestial lion is majestically facing westward as we view its profile.  The moon moves through the region May 11-13, 2019.  Here’s what to look for:

  • May 11: The moon reaches its First Quarter phase at 8:12 p.m. CDT. One hour after sunset, the moon, 7.1 days past its New Phase and 50% illuminated, is high in the southwest, 8.9° to the right of Regulus.

The angular degree measurement is used in astronomy to determine the separations and sizes of objects.  Because objects have various actual sizes and distances from Earth, the degree is the way for us to communicate apparent sizes and apparent separations.  The full moon has an apparent diameter of about 1/2°.  The charts we use typically exaggerate the size of the moon, so the chart cannot be used for a scale with the moon.  The distance from Regulus to Denebola is about 24°.

  • May 12: One hour after sunset, the moon (8.1d, 62%) is 6.2° to the upper left of Regulus.
  • May 13: The moon is closest to Earth at 4:53 p.m. CDT. An hour after sunset, the moon (9.1d, 73%), nearly 60° up in the south, is 8.5° to the lower right of Denebola– the tail of Leo.

2019, May 6-7: Aldebaran, Mars, and the Crescent Moon

(On the chart above, the moon’s size is exaggerated.  At this scale, the star Zeta would be covered in May 7.)

The chart shows the western sky at about 1 hour after sunset.  Start looking for the moon beginning about 30 minutes after sunset.  Check your sources — television, newspaper, or Internet — for the time of your local sunset.

On May 6, the crescent moon (2.1 days past the New phase, 5% illuminated), 11° up in the west-northwest, is 2.2° to the upper right of Aldebaran, the brightest star in Taurus.   The moon is nearly 14° below Mars.

An hour after sunset, locate Mars between Elnath and Zeta Tauri, 4.5° to the lower left of Elnath and 3.4° to the upper right of the Bull’s southern horn.

On the next evening, an hour after sunset, the moon (3.1 days old, 11% illuminated) is 0.3° to the lower left of Zeta Tauri. Mars is 3.3° to the upper right of the star.

Use a binocular to look that the moon these two evenings.  You’ll notice that the moon’s night portion is slightly illuminated.  This is known as Earthshine.  From the moon, Earth is nearly full, and would be very bright to an observer on the lunar surface; it is bright enough to cast shadows on the moon’s night portion.  Earthshine is from reflected sunlight from Earth’s clouds, land, and oceans.  This sunlight gently illuminates the night portion of the moon in the same manner our planet is illuminated when the moon is near its Full phase.  Click here for an example of the crescent moon with Earthshine.

2019, May 2: Morning Star Venus Meets Crescent Moon

On the morning of May 2, about 30 minutes before sunrise, the moon (27.1 days past the New phase, 7% illuminated) — a thin waning crescent phase — is 4.3° to the lower right of Venus. Look for them low in the east.  Venus is only about 5° up in the east.

Check your local sources — newspaper, television, or internet — for the time of sunrise at your location.  Although they are lower at that time, start looking for them about 45 minutes before the time of your local sunrise.

To find this pair, you’ll need a clear eastern horizon.  Stand on a hill or in an open spot with no trees or houses nearby.

The time interval between the beginning of morning twilight and sunrise grows 24 minutes from this morning through mid-June.  While Venus is rising at the same time interval before sunrise for the next month, it appears in a brighter sky.

The moon is New on May 4.  Look for it during the early evening of May 6 in the west as the sky darkens.

2019, April 22-26: The Morning Moon With Jupiter and Saturn

The moon moves past the morning planets — Jupiter and Saturn — during late April 2019.  The chart above shows them about one hour before sunrise.  Check your local sources — TV, newspaper, Internet — for your local sunrise time.  Here are the highlights of the mornings:

  • April 22: At the beginning of morning twilight, the moon (17.0 days old. 90% illuminated), nearly 28° up in the south-southwest, is over 7° to the upper right of Antares.
  • April 23: At 12:30 a.m. CDT, the moon (17.9d, 90%), about 10° up in the southeast, is 2.8° to the upper right of Jupiter. At the beginning of morning twilight, the moon (18.0d, 82%) is 1.5° to the upper right of Jupiter, 25° up in the south. Saturn is 20° up in the south-southeast, about 26° east of Jupiter.
  • April 24: At the beginning of morning twilight, the moon (19.0d, 74%) is nearly between Jupiter and Saturn. The moon is at the top of the lid of the Teapot of Sagittarius, above Kaus Borealis.
  • April 25: At the beginning of morning twilight, now 105 minutes before sunrise, the moon (20.0d, 65%) is 2.7° to the lower right of Saturn.
  • April 26: At the beginning of morning twilight, the moon (21.0d, 55%) is 9.8° to the lower left of Saturn.