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In this issue of SpaceTides

Don't be coaxed into a hoax by the Mars myth...  again

Many of you might have received it again. The (annual) malicious e-mail hoax claiming that, on 27 August, Mars will come extremely close to the Earth. So close in fact, that it will look as large as the "full moon"! It also claims that Mars will easily be visible and only within 56 million km from the Earth.  Quick! Run away! (not from Mars, from the hoax!)

Let's again set the record straight:
1. For the month of August 2007, Mars will only rise after 1h00 am.
2. On 27 August 2007, Mars will not be 56 million km away, it will be 175.5 million km away.
3. If Mars is 56 million km from the Earth, it will NOT appear as large as the full moon. In August 2003 Mars came within 56 million km, the closest in 60,000 years, and it was nothing more than a bright speck of light in the sky - the average Mr. Smith and his husky wouldn't even have noticed at all. If Mars came so close to the Earth as to appear as large as our moon, it will not only disturb the Earth's orbit around the Sun, but may also wreak havoc with the tides in the oceans. So please ignore that email and resist the temptation to pass it on to your astronomically-challenged friends!

Go to this Snopes.com article to read the hoax (green box). 

1. Spaceflight news from around the world

Computer rendering of the Phoenix lander on Mars. Credit: NASA

Mars Phoenix lander approaching launch date
NASA news release dated 9 July 2007. Read full release: source.

NASA's next mission to Mars will look beneath a very cold arctic landscape for conditions favorable to past or present life on the Red Planet. But instead of roving to hills or craters, NASA's Phoenix Mars Lander will claw down into the icy soil of the Red Planet's northern plains. The robot will investigate whether frozen water near the Martian surface might periodically melt enough to sustain a liveable environment for microbes. To accomplish that and other key goals, Phoenix will carry a set of advanced research tools never before used on Mars. Launch is slated for 4-5 August 2007. It will take the probe over 6 months to travel to Mars.

Phoenix homepage: http://www.nasa.gov/mission_pages/phoenix/main/index.html

The K10 Red rover. Credit: NASA

NASA robots practicing in the Arctic for future lunar missions
NASA news release dated 20 July 2007. Read full release: source.

Two NASA robots are surveying a rocky, isolated polar desert within a crater in the Arctic Circle here on Earth. The study will help scientists learn how robots could evaluate potential outposts on the Moon or Mars.

The robots, K10 Black and K10 Red, carry 3-D laser scanners and ground-penetrating radar. NASA is planning to send astronauts back to the moon by 2020. Prior to establishing a lunar outpost, the agency must conduct detailed surveys at a variety of locations to produce maps, look for minerals and water, and learn other details.

NASA plans to accomplish its surveys with an automated orbiting spacecraft, not a robotic lander, but the agency still has a keen interest in advancing the laser scanning technology.

The 3-D laser scanner can map topographic features as far as a kilometer away. The ground-penetrating radar, which JPL developed, can map below ground as deep as 5 meters.

Other news in Spaceflight

Shuttle Endeavour approaching launch date to ISS
Space Shuttle Endeavour is ready to fly to the International Space Station, to mainly deliver a third starboard truss segment. Launch of Endeavour on mission STS-118 is officially set for Aug. 7. This is the 22nd shuttle flight to the International Space Station and STS-118 will be the first flight for Endeavour since 2002. More at NASA.gov.

Mars Rovers caught in huge storms
Rover engineers are growing increasingly concerned about the temperature of vital electronics on NASA's Mars Exploration Rover Opportunity while the rover stays nearly inactive due to a series of dust storms that has lasted for more than a month. Rover Spirit, meanwhile, is also accumulating some dust on solar panels under a sky at Gusev Crater that remains nearly as dusty as the worst Spirit has recorded. From NASA.gov.

2. Astronomy: The Lifecycle of Stars

This poster from the Chandra X-ray observatory website is a simplified portrayel of the stellar evolution of stars with different initial mass: how massive and heavy a star is after being formed will determine its fate later in its life. Go to the Chandra website for large, high-res version of poster.

Stars also go through cycles in their lives. From after their initial formation, they pass through several phases - and eventually "die". Our Sun is an estimated 4.6 billion years old and may live for another 5 billion years (5 000 million) before its gas supplies run out. When our Sun nears the so-called "red giant" phase, it will start swelling up as it sheds its outer gas layers (and scorching the Earth in the process), to eventually form a planetary nebula. All that will remain of the Sun is a "white dwarf star", surrounded by the planetary nebula. A white dwarf is a faint, but very dense star which will eventually die out and form a black dwarf. 110 Earths can fit into the diameter of our Sun at its current size. A white dwarf however, may be as large as the Earth, but a teaspoonful of its matter can weigh several tons! White dwarfs usually consist of carbon and oxygen, or in some cases helium.

The "birth place" of stars are nebulous clouds of hydrogen gas in space.  What will happen to a star during its lifecycle will depend on its initial mass shortly after it formed, and for this purpose we can discern between the following categories of stars:
1) those that have a high mass (8 times or more than our Sun's mass),
2) intermediate-mass stars, with 0.5 to 8 solar masses - the group that includes our Sun; and
3) low-mass stars, with 0.1 to 0.5 solar mass. Objects with less than 0.1 solar mass do not have enough gravitational force to produce the core temperature necessary for hydrogen fusion and won't become a star. They typically remain a "brown dwarf".

Massive stars burn their hydrogen fuel much quicker than do stars with less mass. They don't live very long either: sometimes only a few hundred million years, or if they are really massive, only a few millions! These high-mass stars can blow up in spectacular supernova explosions, forming immense gas clouds (nebulae) in space. They don't leave white dwarf stars behind, but form much more exotic objects such as neutron stars, or even black holes if they are massive enough...

Based on information obtained from NASA Worldbook: http://www.nasa.gov/worldbook/star_worldbook.html

3. Interesting Space Facts

The milky way as seen from Earth

- The path of stars that you see on dark nights in the sky is commonly called the milky way (lower case letters). Our spiral galaxy's name is also called the Milky Way (in capital letters!)

- The milky way represents arms of our spiral Milky Way galaxy and appears so bright because of the numerous stars within it. When you look into the milky way in winter you look into the Sagittarius arm and in summer you look towards the Perseus arm. Our Sun is situated in the Orion arm.

- The galactic centre of the Milky Way Galaxy (capital letters!) lies in the direction of the constellation Sagittarius.       

- The dark patches that you see in the milky way consist of cosmic dust and gas, which obscures the light from the stars in the background. One such example of dust and gas is the “Coal Sack nebula” visible below the Southern Cross.

For an in-depth explanation of our Galaxy's spiral structure and names of its spiral arms, visit Wikipedia.org.

4. The Solar System

Artist rendering of the New Horizons probe on its way to the Kuiperbelt.
Credit: JHUAPL/SwRI

Dwarf planet Pluto

Pluto (named after the Greek god of the Underworld), was discovered in 1930 by Clyde Tombaugh. It is almost 6 billion km (6 000 million) from the Sun. Pluto was designated a dwarf planet in August 2006, after a resolution by the International Astronomical Union that a solar system body must adhere to the definition of a planet. Pluto did not meet the criteria, but did met those of a "dwarf planet".

Pluto's diameter is about 2 300 km, making it smaller than our Moon (our Moon is about 3 400 km in diameter). Pluto is sometimes refered to as a double planet because of its largest moon Charon being half the diameter of Pluto. It has 3 discovered moons: Charon, Hydra and Nix.

Pluto is in fact one of the largest members of a group of icy objects located in an area just beyond Neptune called the "Kuiper Belt". The Kuiper Belt is made up of possibly millions of icy and rocky objects such as asteroids. Scientists believe that some comets come from the Kuiper Belt and the still hypothetical Oort Cloud beyond.

More information on Pluto at Wikipedia: http://en.wikipedia.org/wiki/Pluto
Website for the New Horizon's probe en route to Pluto: http://pluto.jhuapl.edu/

This is the 10th part in a 12-part series about the Solar System.

5. Sky Observation Log

The area around Scorpius and Sagittarius on 21 August 2007.
Credit: Stellarium.

Planets - August 2007
Mercury is visible in the east before the sun rises until about the 8th of August. It reappears in the evening skies later in the month. Venus is shining very bright in the evening skies until mid-month. Mars is visible from after 1h00 in the mornings in Taurus. Jupiter shines almost directly overhead in the evenings, close to the Scorpion. Saturn is saying farewell and can only be seen during the first week after sunset in the west. Uranus is in Aquarius while Neptune is in Capricornus. Dwarf planet Ceres can be found in Taurus, while Pluto is in Sagittarius. Asteroid Vesta is located in Ophiuchus close to Jupiter.

Stars & Constellations - August 2007
Above the northern horizon you will find constellations such as Corona Borealis (the Northern Crown), Hercules the Hero and Lyra the Harp. Rising shortly after Lyra is the early spring constellation of Cygnus the Swan. Above your head you will find the Scorpion, followed by Sagittarius the Archer. The large constellation of Ophiuchus, with its two Serpents, can be found below Scorpius slightly to the north. Aquila the Eagle is visible in all its glory in the north-eastern skies, flying gracefully into the milky way.

Deep Sky Objects for binoculars and telescopes - August 2007
Binoculars: M8 (Lagoon nebula), M20 (Trifid nebula) and M22 (a bright, large globular cluster) all in Sagittarius. NGC 6633 (open cluster) in Ophiuchus.
Telescopes: M11 (Wild Duck open cluster) in Scutum, M17 (Swan nebula) in Sagittarius,
NGC 6397 (a globular cluster) in Ara.

Other night sky phenomena
New Moon on 13 August 2007
Full Moon on 28 August 2007
August 1 to 10: Venus, Saturn and the star Regulus closely group after sunset in west.
August 21: Close pairing of asteroid Vesta, planet Jupiter and natural satellite Moon.


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 infrared image from NASA's Spitzer Space Telescope shows the Helix nebula, a cosmic starlet often photographed by amateur astronomers for its vivid colours and eerie resemblance to a giant eye. "

"The nebula, located about 700 light-years away in the constellation Aquarius, belongs to a class of objects called planetary nebulae. Discovered in the 18th century, these colourful beauties were named for their resemblance to gas-giant planets like Jupiter.  Planetary nebulae are the remains of stars that once looked a lot like our sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible colours. Our own sun will blossom into a planetary nebula when it dies in about five billion years".

Credit: NASA/JPL-Caltech/K. Su (Univ. of Ariz.). Click to go to source (Spitzer: Caltech)

7. Astronomy in Southern Africa

Boyden Observatory open evening on 25 August 2007:
The next Boyden open evening in Bloemfontein will be on 25 August 2007 (Saturday). Please see the press, including local newspapers, for information about times and other details.

ASSA national website updated:
Go to the website of the national Astronomical Society of Southern Africa for the latest news in SA Astronomy and other related info.

What's up in the August night skies on the SAAO website:
http://www.saao.ac.za/public-info/sun-moon-stars/august/

KAT - XDM saw First Light in July 2007
"The eXperimental Development Model (XDM) is a 15-m diameter radio telescope antenna of novel design intended to reduce antenna construction cost per square metre and bring it close to that needed to make Square Kilometre Array (SKA) affordable. IST Holdings are the prime contractors building XDM at Hartebeesthoek."  From HartRAO: http://www.hartrao.ac.za/news/070716XDM_first_light/index.html