Continuing the tour brings us to:

Messier 21

RA: 18h 4m 40s

DEC: -22 deg 30′

Apparent Magnitude: 6.5

M21 is an open cluster of stars in the constellation of Sagittarius. It was discovered and cataloged by Charles Messier on June 5, 1764.

M21 is a relatively young cluster of a mere 4.6 million years of age. It has a few blue giant stars, but Messier 21 is composed mainly of small dim stars. With a magnitude of 6.5, M21 is not visible to the naked eye; however, with the smallest binoculars it can be easily spotted on a dark night.

Messier 22

RA: 18h 36m 24.21s

DEC: -23 deg 54′ 12.2″

Apparent Magnitude: 5.5

M22 is an elliptical globular cluster in the constellation Sagittarius near the Galactic bulge region. It is one of the brightest globulars clusters in the night sky.

M22 is one of the nearer globular clusters to Earth at a distance of about 10,600 light-years away. With a span of 32 arcminutes on the sky, that translates to a spatial diameter of about 100 light-years. An impressive 32 variable stars have been recorded in M22. It is projected in front of the galactic bulge and is therefore useful for its microlensing effect on the background stars in the bulge. With hard work, clear seeing, and a great camera and telescope, these microlensing events can be recorded by amateur astronomers.

Despite its relative proximity to us, this metal-poor cluster’s light is limited by dust extinction, giving it an apparent magnitude of 5.5 making it the brightest globular cluster in the norther hemisphere.

M22 is one of only four globulars clusters that are known to contain a planetary nebula; the other three are M15, NGC 6441 and Palomar 6. The planetary nebula, designated GJJC1, is estimated to be a mere 6,000 years old.

Messier 23

RA: 17h 56.8m

DEC: -19 deg 01′

Apparent Magnitude: 6.9

M23 is an open cluster in the constellation Sagittarius. It was discovered by Charles Messier on June 20, 1764.

Located about 2,150 light-years away from Earth, its radius is around 15-20 light years. There are some 150 identified members in this cluster, the brightest being of magnitude 9.2. M23 can be found with a modestly sized telescope in the rich starfields of the Sagittarius Milky Way. Given the rich star density of the Milky Way, spotting M23 can be a challenge for amateurs.

Messier 24

RA: 18h 17m

DEC: -18 deg 29′

Apparent Magnitude: 4.6

M24, commonly called The Sagittarius Star Cloud is a star cloud in the constellation of Sagittarius, approximately 600 light years wide, which was discovered by Charles Messier in 1764.

The stars, star clusters, nebulae, and other objects comprising M24 are part of the Sagittarius arm of the Milky Way galaxy. Messier described M24 as a “large nebulosity containing many stars” and gave its dimensions as being some 1.5 arc degrees across, an apt description of the star cloud. Some sources improperly identify M24 as the faint cluster NGC 6603, so please be wary of this.

M24 fills a space of significant volume to a depth of 10,000 to 16,000 light-years. This is the most dense concentration of individual stars visible using binoculars, with around 1,000 stars visible within a single field of view.

Messier 25

RA: 18h 31m 36s

DEC: -19 deg 15′

Apparent Magnitude: 4.6

M25 is an open cluster in the Sagittarius constellation. It was discovered by Philippe Loys de Chéseaux in 1745 and included in Charles Messier’s list in 1764.

M25 is at a distance of about 2,000 light-years away from Earth. The spatial dimension of this cluster is about 19 light years across.

Today is the 52nd anniversary of the successful launch of Sputnik, humanities first artificial satellite.

Sputnik was launched into space by the Soviet Union on October 4 1957, far earlier then the United States own Explorer satellite, creating a crisis in America, and igniting the space race between the USSR and USA.

The Satellite

Sputnik was a silver sphere, 585 mm in diameter, hermetically sealed with o-rings, and bearing two omnidirectional antennae. The spacecraft contained a one watt radio transmitter, transmitting on 20.005 and 40.002 MHz; a battery power supply, powering both the radio transmitter and the meteorite detection system; as well as a meteor detection system, consisting of dry nitrogen and a pressure triggered barometric switch. If Sputnik was punctured by a meteor, the nitrogen would rush out of the spacecraft, the switch would be triggered, and the pattern of radio beeps put out would change. The entire system was protected by a heat shield covering the entire sphere.

The radio was attached to two pair of antenna, with one of the pairs being 2.4 meters long, and the other 2.9 meters long. These antenna had a spherically symmetric radiation pattern, so that ground controllers could hear Sputnik no matter what its orientation.

The Crisis

The United States had felt that they were the leaders in missile design and space technology, having spirited away more then their fair share of German scientists and engineers.

However, the launch of Sputnik, and the successive failures of American designs proved otherwise, causing a panic amongst the Americans. “If the Soviets could launch satellites into space, what is going to stop them from launching weapons?”, they reasoned. This fear stimulated lots of science funding, as well as the creation of several government agencies, among them NASA, DARPA, the Polaris missiles, New Math (unfortunately), and modern project management.

Eventually, the Space race would yield the Apollo missions, the unofficial ending to the race, while thirty years later, Soviet Russia would collapse, weakened by poverty, mismanagement, and inadequate food supplies.