Weekend Star Party: NGC 246, NGC 288, and NGC 253

Friday, November 1 - On this day in 1977, Charles Kowal made a wild discovery: Chiron. It was the first discovery of a multitude of tiny, icy bodies that lie in the outer reaches of our solar system. Collectively known as Centaurs, they reside in unstable orbits between Jupiter and Neptune and are almost certainly "refugees" from the Kuiper Belt.

Tonight let's go for something small but white-hot as we head for a dwarf star and planetary nebula, NGC 246. You'll find it just a bit more than a fistwidth north-northeast of Beta Ceti (RA 00 47 03.34 Dec -11 52 18.9).

NGC 246 - Credit: Palomar Observatory Courtesy of Caltech
NGC 246 - Credit: Palomar Observatory Courtesy of Caltech

First discovered by Sir William Herschel and cataloged as object V.25, this 8th magnitude planetary nebula has a wonderful patchy, diffuse structure that envelops four stars. Around 1600 light-years away, the nebulosity you can see around the exterior edges was once the outer atmosphere of a star much like our own Sun. At the center of the nebula lies the responsible star - the fainter member of a binary system. While it is now in the process of becoming a white dwarf, we can still enjoy the product of this expanding shell of gas that is often called the "Skull Nebula."

Saturday, November 2 - Today celebrates the birth of an astronomy legend - Harlow Shapely. Born in 1885, the American-born Shapley paved the way in determining distances to stars, clusters, and the center of our Milky Way galaxy. Among his many achievements, Shapely was also the Harvard College Observatory director for many years. Today in 1917 also represents the night that first light was seen through the 100" Hooker telescope at Mount Wilson Observatory - the largest telescope in the world at the time.

Of course, Dr. Shapley spent his fair share of time on the Hooker telescope as well. One of his many points of study was globular clusters, their distance, and their relationship to the halo structure of our galaxy. Tonight let's have a look at a very unusual little globular located about a fistwidth south-southeast of Beta Ceti and just a couple of degrees north-northwest of Alpha Sculptor (RA 00:52:47.5 Dec -26:35:24), as we have a look at NGC 288.

NGC 288 - Credit: Palomar Observatory Courtesy of Caltech
NGC 288 - Credit: Palomar Observatory Courtesy of Caltech

Discovered by William Herschel on October 27, 1785, and cataloged by him as H VI.20, this class X globular cluster blew apart scientific thinking in the late 1980's when a study of perimeter globulars showed it to be more than 3 million years older than similar globular clusters. The study used the color magnitude diagrams of Hertzsprung and Russell: By identifying both its blue and red branches, it was shown that many of NGC 288's stars are being stripped away by tidal forces and contributing to the formation of the Milky Way's halo structure. In 1997, three additional variable stars were discovered in this cluster.

At magnitude 8, this small globular is easy for southern observers, but faint for northern ones. If you are using binoculars, be sure to look for the equally bright spiral galaxy NGC 253 to the globular cluster's north.

Sunday, November 3 - A On this day in 1955, one of the few documented cases of a person being hit by a meteorite occurred. What are the odds on that? After around 2:00 a.m. will be the peak of the Southern Taurid meteor shower. Well known for producing fireballs, the Taurid radiant area is, of course, the constellation of Taurus and red giant Aldeberan, but did you know the Taurids are divided into two streams?

It is surmised that the original parent comet shattered as it passed our Sun around 20,000 to 30,000 years ago. The larger "chunk" continued orbiting and is known as periodic comet Encke. The remaining debris field turned into smaller asteroids, meteors and larger fragments that often pass through our atmosphere creating the astounding "fireballs" known as bolides. Although the fall rate for this particular shower is rather low, at seven per hour, these slow traveling meteors (27 km or 17 miles per second) are usually very bright and appear to almost "trundle" across the sky. With the chances high all week of seeing a bolide, this makes a bit of quiet contemplation under the stars worthy of a morning walk.

Laika Courtesy of NASA
Laika Courtesy of NASA

In 1957 the Russian space program launched its first "live" astronaut into space - Laika. Carried on board Sputnik 2, our canine hero was the first living creature to reach orbit. The speedily developed Sputnik 2 was designed with sensors to transmit the ambient pressure, breathing patterns and heartbeat of its passenger, and also had a television camera on board to monitor its occupant. The craft also studied ultraviolet and x-ray radiation to further assess the impact of space flight upon live occupants. Unfortunately, the technology of the time offered no way to return Laika to Earth, so she perished in space. On April 14, 1958, Laika and Sputnik 2 returned to Earth in a fiery re-entry after 2,570 orbits.

Since we've got the scope out, let's go have another look at that galaxy we spied last night. Discovered by Caroline Herschel on September 23, 1783, NGC 253 (RA 00 47.6 Dec -25 17) is the brightest member of a concentration of galaxies known as the Sculptor Group, near to our own local group and the brightest of all outside it. Cataloged as both H V.1 and Bennett 4, this 7th magnitude beauty is also known as Caldwell 65, and due to both its brightness and oblique angle is often called the "Silver Dollar Galaxy."

As part of the SAC 110 best NGCs, you can even spot this one if you don't live in the Southern Hemisphere. At around 10 million light-years away, this very dusty, star-forming Seyfert galaxy rocks in even a modest telescope!

Until next week, keep reaching for the stars!