Mars Visits the Beehive Star Cluster

Considering the thousands of stars in the sky, it is surprisingly rare to see a star in the same telescope field as one of the planets. The reason is that planets generally require a lot of magnification, and this severely limits the field of view of a telescope when looking at a planet.

On Thursday morning, August 20, just before dawn, the planet Mars will pose in front of a swarm of stellar bees, the Beehive Cluster (Messier 44) in the constellation Cancer. Credit: Starry Night software.

On the morning of Thursday, August 20, we will get a special treat, when the planet Mars appears in the midst of hundreds of stars: the open star cluster known as the Beehive, Praesepe, or Messier 44.

This star cluster is called “the Beehive” because of its resemblance to a swarm of bees. It is also known as “Praesepe,” which is Latin for “manger,” because of its position between the stars Asellus Borealis and Asellus Australis, the northern and southern donkeys. Finally, it is number 44 in Charles Messier’s famous catalog of deep sky objects.

Located 590 light years from the sun, the Beehive is one of the nearest and brightest star clusters in the sky. Its several hundred stars are concentrated in a volume 16 light years across, and it actually outshines all of the individual stars in its constellation, Cancer.

You may be wondering where Mars is in the sky, because we haven’t heard much about it lately. That is because it has been on the far side of the sun in recent months, and impossible to see. It is only now emerging from the sun’s glare and reappearing in the morning sky, just before dawn. Look for it around 5 a.m. this week low in the northeastern sky, and be sure to use binoculars if you want to see the Beehive behind it.

Even in the smallest telescope, Mars should make a pretty picture lying in front of the many stars of the Beehive. But be sure to catch it Thursday or Friday morning, because by Saturday it will have passed the Beehive.

Mars itself will be a disappointing sight, as it is still very far away from Earth, 2.5 astronomical units distant and less than 4 arc seconds in diameter. It won’t be large enough to show much detail until mid-March next year, heading towards its most favorable opposition in over a decade 

Sky Events For August 2015

Moon Phases

Thursday, August 6, 10:03 p.m. EDT

Last Quarter Moon

The Last Quarter Moon rises around midnight and sets around 3 p.m. It is most easily seen just after sunrise in the southern sky.

Friday, August 14, 10:53 a.m. EDT

New Moon

The Moon is not visible on the date of New Moon because it is too close to the Sun, but can be seen low in the East as a narrow crescent a morning or two before, just before sunrise. It is visible low in the West an evening or two after New Moon.

Saturday, August 22, 3:31 p.m. EDT

First Quarter Moon

The First Quarter Moon rises around noon and sets around midnight. It dominates the evening sky.

Saturday, August 29, 2:35 p.m. EDT

Full Moon

The August Full Moon is known as the Corn Moon, Sturgeon Moon, Red Moon, Green Corn Moon, or Grain Moon. It rises around sunset and sets around sunrise; this is the only night in the month when the Moon is in the sky all night long. The rest of the month, the Moon spends at least some time in the daytime sky.

Observing Highlights

Uranus and the Moon

Wednesday/Thursday, August 5/6, dawn

The Moon will be close to Uranus just before sunrise. In southern South America, the Falkland Islands, and parts of Antarctica, the Moon will actually occult Uranus.

Mercury and Jupiter within 0.6 degrees

Thursday, August 6, dusk

Mercury and Jupiter will pass close to each other, appearing within the same telescope field.

Mercury, Jupiter and Regulus within 1 degree

Friday, August 7, dusk

These three bright objects will form a tight triangular pattern low in the western sky after sunset.

Aldebaran and the Moon

Saturday, August 8, early morning

The waning crescent moon will pass close to the bright red star Aldebaran low in morning twilight. The Moon will occult Aldebaran as seen from the Middle East, eastern Europe, northwestern Asia, Scandinavia, Russia, Alaska, and northwestern Canada.

Jupiter and Regulus within 0.5 degrees

Monday, August 10, dusk

Jupiter will pass just north of the bright star Regulus in the constellation Leo.

Perseid meteor shower peaks

Thursday, August 13, 2 a.m.

The Perseid meteor shower is always the most reliable in the year, and this year benefits from having the moon out of the sky for most of the night. Although Perseid meteors can be seen at any time of night, there are always more meteors after midnight because then the Earth is heading directly into the shower. Although they appear to radiate from a point in the constellation Perseus in the northeastern sky, they can be seen anywhere in the sky.

Mars in the Beehive

Thursday, August 20, before dawn

Mars, just past conjunction with the sun, passes in front of the Beehive Cluster, Messier 44.

Moon close to perigee

Saturday, August 29, 8 p.m. local time

The moon will be closest to the Earth at 11 a.m. on August 30, 222,631 miles or 358,290 km. distant. The moon will be below the horizon at that time for observers in North America. The best time to observe this “supermoon” will be just after it rises on Saturday night, August 29. Those living near the ocean should expect higher tides than normal for the next few days.

Planets

Mercury is visible low in the western sky after sunset for most of the month, This apparition is more favorable for observers in the Southern Hemisphere.

Venus moves from the evening to the morning sky on the 15th, but will be hard to observe for northern observers because of its closeness to the sun. Southern observers will have an easier time, and on the 15th may actually be able to observe Venus as a morning star in the east and an evening star in the west.

Mars reappears in dawn twilight after its conjunction with the sun on June 14.

Jupiter is too close to the sun to observe this month.

Saturn is well placed in Libra in the evening sky.

Uranus rises in the late evening in Pisces. 

Neptune rises in the mid-evening in the constellation Aquarius.


Catch The Double Crescents This Week: Venus and the Moon

On Saturday evening, July 18, the crescent moon, moving eastward in the sky, will pass directly below the crescent planet Venus, moving westward, soon to pass below the sun.

On Saturday, July 18, the moon passes just below the planet Venus, both objects showing narrow crescents.  Credit: Starry Night software.

Both objects are being back-lit by the Sun, so that both appear in our sky as crescents. The moon is just three days past new moon, so only nine percent of its disk is lit by the sun. The remaining 91 percent is lit by sunlight reflecting off the surface of the Earth, what is called “earthshine” or “earthlight.” Sometimes this view is also called “the old moon in the new moon’s arms.”

To the naked eye, Venus appears like a brilliant pinpoint of light. Turn your binoculars on it, and that slight additional magnification will allow you to see that Venus is also a narrow crescent.

Because Venus is farther away than the moon, it is lit by the sun at a slightly different angle, so is nineteen percent illuminated, a slightly fatter crescent than the moon.

Some observers have suspected a faint glow coming from the part of Venus not in direct sunlight, a phenomenon called “the ashen light.” No one knows exactly what causes this glow, but it has been reported by many experienced astronomers. Spectroscopic observations have shown pulses in the light, so it might be due to lightning in the hot acidic atmosphere of Venus.

As mentioned above, even small binoculars provide enough magnification to turn the naked-eye pinpoint of Venus into a visible crescent. This is one of many objects in the sky which are revealed or enhanced in binoculars, which is why they are considered an essential tool for all serious skywatchers.

Binoculars for astronomy should have a front aperture of at least 50 millimeters (2 inches). This is seven times the diameter of the fully dark-adapted eye. Such a small binocular has seven times the resolution and 50 times the light-gathering power of the naked eye. 50 millimetre binoculars come in two magnifications, 7 power (7x50) and 10 power (10x50). Both are very useful for astronomy, but I prefer the 10x50 because of its slightly higher magnification and better contrast in a bright sky. I find more powerful binoculars too heavy to hold steadily for any length of time, and mounting them on a tripod defeats the ease of use.