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In this issue of SpaceTides

Dear SpaceTides Subscribers

Welcome to all new subscribers, who came on board at Scope-X in Johannesburg in April, as well as those who subscribed at Boyden Observatory in Bloemfontein in the past 2 months.

For current subscribers: don't worry - you didn't miss the May issue of SpaceTides, I missed it! This issue will serve as the newsletter for May and June.

In future, the "Photo Sense" section will show pictures taken by orbiting Space Telescopes.

Regards,

Gerrit Penning
Editor

Total subscribers as at 1 June 2007: 815 (+76 from previous issue #53)

1. Spaceflight news from around the world

Shuttle Atlantis ready on its launchpad. NASA/Ken Thornsley

Space Shuttle preparing for launch on 8 June 2007
Extracts from a NASA news release dated  31 May 2007.

NASA senior managers selected June 8 as the official launch date for space shuttle Atlantis.  7 astronauts are scheduled to lift off on mission STS-117 to the International Space Station.

During the 11-day mission and three spacewalks, the crew will work with flight controllers at NASA's Johnson Space Center, Houston, to install a 17-ton segment on the station's girder-like truss and deploy a set of solar arrays. The mission will increase the International Space Station's power capability in preparation for the arrival of new science modules from the European and Japanese space agencies.

Astronaut Clayton Anderson will replace current station crew member Sunita Williams, who has lived on the station since December. Williams will return to Earth on Atlantis.

2. Astronomy news from around the world

Note that the blue colour is only a representation of how the dark matter's gravity distorts light waves from background galaxies, it is not the dark matter itself! Dark matter hasn't been seen yet as it doesn't reflect light. NASA/ESA/JHU

Hubble sees ghostly ring of dark matter around galaxy cluster
Hubble ESA Information Centre news release dated 15 May 2007

Astronomers using NASA's Hubble Space Telescope have discovered a ghostly ring of dark matter that formed long ago during a titanic collision between two massive galaxy clusters. The ring's discovery is among the strongest evidence yet that dark matter exists. Astronomers have long suspected the existence of the invisible substance as the source of additional gravity that holds together galaxy clusters. Such clusters would fly apart if they relied only on the gravity from their visible stars. Although astronomers don't know what dark matter is made of, they hypothesize that it is a type of elementary particle that pervades the universe. Dark matter makes up the bulk of the universe's material and is believed to make up the underlying structure of the cosmos.

The Hubble composite image at the left shows the ring of dark matter in the galaxy cluster Cl 0024+17. The ring-like structure is evident in the blue map of the cluster's dark matter distribution. The map was derived from Hubble observations of how the gravity of the cluster distorts the light of more distant galaxies, an optical illusion called gravitational lensing.

Although astronomers cannot see dark matter, they can infer its existence by mapping the distorted shapes of the background galaxies. This map is superimposed on a "Hubble Advanced Camera for Surveys" image of the cluster taken earlier in November 2004. Read full article.

One of the most energetic events ever detected in space
Chandra Press Room article dated 30 May 2007

NASA's Chandra X-ray Observatory captured a sight of awesome upheaval. It has seen an arc of incredibly hot gas extending over two million light years, which requires one of the most energetic events ever detected. Although astronomers cannot exactly say what formed this arc of gas, they can provide two interesting explanations:

The favored explanation is that two massive galaxy clusters are undergoing a collision at a speed of 6.4 million km/h. Shock waves generated by the collision of the two clusters' hot gas clouds could produce a sharp change in pressure along the boundary where the collision is occurring, giving rise to the observed arc-shaped structure.

Another possible explanation is that the disturbance was caused by an outburst generated by the infall of matter into a supermassive black hole located in a central galaxy. The black hole inhales much of the matter but expels some of it outward in a pair of high-speed jets, heating and pushing aside the surrounding gas.

The image on the left is what you see if you look at this area in optical wavelengths. The same area of the sky appears dramatically different when viewed in X-rays (Chandra image at the right).

An arc-like feature to the lower left in the cluster's hot gas is about 2 million light years long (X-ray image).

Credit: NASA/CXC/CfA/R.P.Kraft; Optical: Pal.Obs. DSS

Read full article.

3. Interesting Space Facts

NASA's Space Shuttle

-The outside skin of the shuttle can reach temperatures of up to 1 650 °C upon re-entry into Earth's atmosphere.
When the liquid hydrogen in the space shuttle's main engine is burned with liquid oxygen upon launch, the temperature in the engine's combustion chamber increase to more than 3 300 °C. Compare these figures with the Sun's surface temperature of about 6 000 °C... (although the Sun's core temperature is an estimated 15 million degrees Celsius).

-After lift-off, it takes only eight minutes for the space shuttle to reach its orbit around Earth and travel at its orbital speed of over 27,300 kilometers per hour (equal to travelling between Bloemfontein and Johannesburg in only 52 seconds...)

-The turbo pump on the main engine of the Shuttle is so powerful that it could drain an average family-sized swimming pool in only 25 seconds.

-The main engine of the space shuttle weighs only 1/7th as much as a train locomotive engine does, but delivers as much horsepower as 39 locomotives.

-Kennedy Space Centre's two "Crawlers" are the largest tracked vehicles on Earth. They are used to transport the shuttle on its platform from the Vehicle Assembly Building (VAB) to the launch pad, but takes almost 5 hours to do so at 1.6 km/h!

NASA Human Spaceflight website

4. The Solar System

The planet Neptune, photo taken by the venerable Voyager 2 space probe. Credit: NASA-JPL.

Neptune was the first planet discovered using mathematical prediction rather than through telescopic observations. Disturbances in the orbit of Uranus led astronomers to theoretically determine Neptune's existence. It was subsequently found by telescope.

Neptune is the 8th planet from the Sun and the 4th largest in the solar system. As with Uranus, Neptune is commonly referred to as an "ice giant", consisting of molten rock and metal in its core surrounded by a mantle of icy rock, water, ammonia and methane.

The planet's vast atmosphere consists mostly of hydrogen and helium. Its blue appearance is due to a small presence of methane. Neptune has the strongest winds of all the planets; some has been measured moving as mush as 2,100 km/h.

The planet has a very faint ring system. It has 13 discovered moons, of which Triton is the largest. Neptune has not been orbited by a satellite yet: the famous Voyager 2 probe did however, fly by Neptune while on its tour of the outer gas giants.

More at Wikipedia.org.
This is the 9th part in a 12-part series about the Solar System.

5. Sky Observation Log

Looking east in the June 2007 evenings towards Scorpius, with bright Jupiter dominating the view.

Credit: Stellarium.

Planets - mid June 2007
Mercury is visible in the evening sky until the 11th of June. Venus shines remarkably bright in the evening a few hours after sunset in the north-west, in the direction of the Cancer constellation (distance from Earth: 0.65 AU, magnitude -4.2). Mars rises in the morning skies around 3h00. Jupiter can be seen throughout the night, located below Scorpius. It shines quite bright! (distance from Earth: 4.3 AU, magnitude -2.2).  Saturn can be seen in the evening skies, until about 21h00, in the constellation of Leo. For telescopes only: Uranus can be seen from after midnight, while Neptune is visible for most of the night.

Stars & Constellations - June 2007
There is still some time to catch the autumn constellations such as Corvus, Crater, Hydra, Leo etc. If you are interested in galaxy hunting, the time is NOW! Especially well placed in the evening sky is Virgo, full of faint galaxies.  Scorpius is rising in the east, leading in deep winter for its southern hemisphere observers. It is littered with beautiful binocular objects (see below). Bootes, with its bright star Arcturus is rising in the north-east. The Southern Cross, with Centaurus surrounding it, is situated high in the southern skies.

Deep Sky Objects for binoculars and telescopes - June 2007
Binoculars:
Coma Berenices Star Cluster (even visible with the unaided eye) above the northern horizon.
M6: "Butterfly Cluster". Beautiful small open cluster below the tail of Scorpius (left of M7).
M7: "Ptolemy's Cluster". Large and bright open cluster also below the Scorpion's tail

Telescopes:
NGC 6231: Bright open cluster in the tail of Scorpius, surrounded by the "Lizard" star field.
NGC 3242 (faint!) "The Ghost of Jupiter" planetary nebula. For larger telescopes.
M83 (faint!) Spiral galaxy in Hydra called the Southern Pinwheel.
M104 (faint!) The Sombrero Galaxy. No doubt one of the best galaxies in the night sky.

Full Moon on 1 June and 30 June
New Moon on 15 June
Venus close to M44 Beehive cluster on 13 June 2007 (north-west)

Sources: detailed sky phenomena can be found in the 2007 Sky Guide handbook. Where are all these objects situated? Contact us for a free sky map, or download Stellarium.

 6. Photo Sense

"This majestic view taken by NASA's Spitzer Space Telescope tells an untold story of life and death in the Eagle nebula, an industrious star-making factory located 7,000 light-years away in the Serpens constellation. The image shows the region's entire network of turbulent clouds and newborn stars in infrared light". More info.
Image credit: NASA/JPL-Caltech/N. Flagey (IAS/SSC) & A. Noriega-Crespo (SSC/Caltech)

7. Astronomy in Southern Africa

ASSA National's website updated
The website of the National Astronomical Society of Southern Africa has been updated with the latest news in SA Astronomy and sky information for June 2007: http://assa.saao.ac.za

Latest on SKA/meerKAT
Read more about one of South Africa's most exciting astronomy projects.  The latest newsletter can be found at http://www.ska.ac.za/newsletter/index.html.

SA's second satellite: launch postponed until admin issues are resolved
Read an article on Mail & Guardian's website regarding the satellite's launch delay.

Want to build your own telescope? Join an astronomy club?
The best way to start with astronomy and star gazing as a hobby is to let someone familiar with it show you how to start. Go to a meeting of an astronomy club in Southern Africa.