Aug/Sept 2020

by Bobby

12 Sep 2017 : 20:18


The Night Skies of August/September

The bright stars Altair, Deneb, and Vega form a prominent triangle that is well seen on August evenings from all but the most southerly latitudes. In the northern hemisphere, it is known as the Summer Triangle. Another major site for northern observers is the Perseid meteor shower, visible in mid-month.

Days and nights become equal in length as the equinox approaches, around September 23, marking the start of northern fall and southern spring. The Great Square of Pegasus is well placed for observers in northern latitudes, while in the southern hemisphere the brightest stars are in the western sky.

The Small Magellanic Cloud

by Bobby

18 Sep 2017 : 02:09
 None    September


The SMC Irregular Galaxy

This is the smaller, fainter, and more distant of two irregularly shaped small galaxies accompanying our own. To the naked eye, it looks like a cut off part of the Milky Way. The cluster to its bottom right is NGC 104. It has been proposed by astrophysicists D. S. Mathewson, V. L. Ford and N. Visvanathan that the SMC may in fact be split in two, with a smaller section of this galaxy behind the main part of the SMC (as seen from our perspective), and separated by about 30,000 ly. They suggest the reason for this is due to a past interaction with the LMC splitting the SMC, and that the two sections are still moving apart. They have dubbed this smaller remnant the Mini Magellanic Cloud.

47 Tucanae

by Bobby

18 Sep 2017 : 02:06
 None    September


Globular Cluster Located in Tucana

Also known as 47 Tucanae, this is the second most prominent globular cluster in the entire sky - only Omega Centauri is brighter. To the naked eye, it resembles a hazy star. It appears in the sky near the Small Magellanic Cloud but is actually within our own galaxy. It is not yet clear whether 47 Tucanae hosts a central black hole. Hubble Space Telescope data constrain the mass of any possible black hole at the cluster's center to be less than approximately 1,500 solar masses. However, in February, 2017, astronomers announced that a black hole of some 2,200 solar masses may be located in the cluster; the researchers detected the black hole's signature from the motions and distributions of pulsars in the cluster.

Dumbbell Nebula

by Bobby

18 Sep 2017 : 02:05
 None    September


A Gorgeous Nebula Located in Vulpecula

The easiest planetary nebula to see with binoculars lies in the often-overlooked constellation of Vulpecula, midway between the bright stars Deneb and Altair. Its popular name, the Dumbbell Nebula, comes from its structure - more like a bow tie than a dumbbell - but this is visible only through a telescope. Like many nearby planetary nebulae, the Dumbbell contains knots. Its central region is marked by a pattern of dark and bright cusped knots and their associated dark tails. The knots vary in appearance from symmetric objects with tails to rather irregular tail-less objects. Similarly to the Helix Nebula and the Eskimo Nebula, the heads of the knots have bright cusps which are local photoionization fronts.

Delta Cephei

by Bobby

18 Sep 2017 : 01:21
 None    September


The Double Star Delta Cephei located in Cepheus

This is the prototype of Cepheid variable stars that are used for finding distances in space. The brightness of Delta Cephei rises and falls every 5 days as it pulsates in size; at its peak, the star is more than twice as bright as when at its faintest. Changes in its brightness can be followed with the naked eye by comparing it with nearby stars of known magnitude. Delta Cephei is also an attractive double star, having a fainter companion that is visible with the smallest telescopes.

Stars of this type are believed to form with masses of 3–12 times that of the Sun, and then have passed through the main sequence as B-type stars. With the hydrogen consumed in their core region, these unstable stars are now passing through later stages of nuclear burning.[16] The estimated mass of Delta Cephei, as derived from the color index, is 4.5 ± 0.3 times the mass of the Sun. By comparison, the mass derived from evolutionary models is 5.0 - 5.25 times the Sun's mass.[4] At this stage of its evolution, the outer layers of the star have expanded to an average of 44.5 times the girth of the Sun.

Delphinus the Dolphin

by Bobby

16 Sep 2017 : 07:45
 None    September


Look for Delphinus high in the sky this month...

Description of Delphinus
Delphinus is a constellation in the northern sky, close to the celestial equator. Its name is Latin for dolphin. Delphinus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains among the 88 modern constellations recognized by the International Astronomical Union. It is one of the smaller constellations, ranked 69th in size.

Delphinus' brightest stars form a distinctive asterism that can easily be recognized. It is bordered (clockwise from north) by Vulpecula the fox, Sagitta the arrow, Aquila the eagle, Aquarius the water-carrier, Equuleus the foal and Pegasus the flying horse.

Points of Interest

Gamma Delphini
A double star. A small telescope will separate the two components, which appear yellow and white, of magnitudes 4.3 and 5.2. Both stars lie approximately 100 light-years away. A fainter and closer pair of 8th-magnitude stars, known as Struve 2725 (about 125 light-years away), should be visible in the same field of view.

Job's Coffin
A name given to the box shape formed by the four stars Alpha, Beta, Gamma and Delta Delphini, all of which are of 4th magnitude.

Andromeda the Princess

by Bobby

15 Sep 2017 : 02:27
 None    September


Andromeda is high in the Sky all this Month

Description Of Andromeda

Andromeda is one of the most famous constellations. Andromeda depicts the princess in Greek myth who was chained to a rock as a sacrifice to a sea monster but was saved by the hero Perseus. The constellation contains the nearest major galaxy to us, M31, the Andromeda Galaxy, which is the most distant object visible to the naked eye. In Chinese astronomy, the stars that make up Andromeda were members of four different constellations that had astrological and mythological significance; a constellation related to Andromeda also exists in Hindu mythology. Andromeda is the location of the radiant for the Andromedids, a weak meteor shower that occurs in November.

Points of Interest

The Andromeda Galaxy (M31)
 A spiral galaxy, similar to the Milky Way but larger. On a clear, dark night, it can be seen by the naked eye as an elongated smudge. With binoculars or a small telescope, it looks much larger, extending for several Moon diameters. Even so, this is only the central part of the galaxy, and a larger telescope is needed to see any trace of its spiral arms. Lying about 2.5 million light-years away, M31 is the largest galaxy in the Local Group. It has two small elliptical companion galaxies (the equivalent of our Magellanic Clouds), M32 and NGC 205 (or M110), which can be seen with a telescope with an aperture of 4 in (100 mm) or more.

NGC 752
 An open cluster, visible through binoculars, consisting of faint stars spread over an area of sky wider than the full Moon. It lies about 1,300 light-years away.

NGC 7662
 A planetary nebula, about 4,000 light-years away. It looks small but prominent through a telescope, like a blue-green star of 9th magnitude; high magnification reveals a rounded outline, like an out-of-focus star.

Gamma Andromadea
 One of the most attractive double stars in the sky. It appears to the naked eye as a single star of magnitude 2.1, but even a small telescope will reveal an orange-colored primary, which is a giant star, and a blue companion of 5th magnitude.