Astronomy: The Week Ahead – Sun 15 Mar to Sat 21 Mar 2015


Sunday March 15

Aquila “the Eagle” is a summer constellation that can currently be seen in the southeast before sunrise. It is dominated by its brightest star, magnitude 0.75 Altair, which is 17 light years from us. The distinctive diamond shape of Aquila defines the eagle’s wings, as it flies along the Milky Way. Aquila is sometimes called “the graveyard of stars” as it contains many planetary nebulae, stars at the ends of their lives. Out in front of Aquila are several smaller constellations, created to fill empty spaces in the sky.


Monday March 16

Two famous constellations in the morning sky currently are Sagittarius and Scorpius. Scorpius, on the right, is the very familiar shape of a scorpion. Sagittarius though is rarely seen as the constellation, but rather, an “asterism” known as The Teapot. An asterism is a shape made from stars that is not a constellation. Here you can see Sagittarius (The Archer) includes The Teapot (highlighted), but extends around and below the asterism. On a dark night, look at The Teapot and see if you can discern the “steam” coming from its spout, in the form of the Milky Way.


Tuesday March 17

It’s always fun to observe solar system events, as we can see changes occurring.

Shadow transits on Jupiter are a favorite, as the shadows from Jupiter’s moons make inky black spots on the disk of the planet. Late tonight Io and its shadow transit.

Here are two transits you can observe this week:

Moon Date Start Date Finish
Io 3/17 23:49 3/18 02:10
Europa 3/21 20:17 3/22 02:17


Wednesday March 18

NGC 2359 is an emission nebula in Canis Major. While often overlooked, it is rich in detail and very pleasing to observe. You’ll need darker skies and a narrowband filter such as Orion’s UltraBlock will help bring out its details. Once you observe this object, it will become a favorite.

It is located 16,000 light years distant, and has a size of 8 arc-minutes. Radiation from a super-hot Wolf-Rayet star is causing the nebula to fluoresce. Another object similar to this in the summer sky is the Crescent Nebula in Cygnus.


Thursday March 19

Antares is well known as the heart of Scorpius, the scorpion. A red giant star, if placed where our sun is, it would extend out beyond the orbit of Mars. And, it is so light, it would float in water.

Did you know Antares is a double star? Its companion is known as The Green Pea. It takes good seeing (steady atmosphere) to separate the pair, and the Green Pea is often lost in the glare of bright Antares, but you can do in a telescope at moderately high power. Antares is magnitude 0.96, and the companion 5.5. Antares is 370 times brighter!


Friday March 20

New Moon is here! A full night of dark sky observing to welcome spring. Occasionally the New Moon is directly along the ecliptic, and we experience a solar eclipse. Today there is a Total Solar Eclipse, but it is mostly over the Arctic and north Atlantic. A partial eclipse will be visible to observers in Europe and Africa.

Today also marks the Vernal Equinox, beginning of spring. It occurs at 3:45 P.M. PDT.


Saturday March 21

NGC 2169 is a fun open cluster to observe in Orion, discovered by Italian astronomer Giovanni Batista Hodierna in 1654. At magnitude 5.9, it is at the threshold of naked-eye visibility. It is actually two open clusters in one, Collinder 38, and Collinder 83, around 3800 light years from us. What makes this object fun is its striking resemblance to the number 37. It’s hard to believe when you see it!

Happy viewing!


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