Toutatis Safely Passes the Earth

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Toutatis Safely Passes the Earth

http://www.universetoday.com/am/publish/toutatis_safely_passes_earth.

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Summary - (Sep 29, 2004) As predicted, Asteroid Toutatis made its

closest approach to the Earth today, passing a mere 1.5 million km

(930,000 miles) away from our planet - 4 times the distance from the

Earth to the Moon. The 4.6 km (2.9 mile) long asteroid hasn't made

an approach this close since 1353. Since it was first discovered in

1989, Toutatis has been closely studied by astronomers because it

has an orbit that brings it close to the Earth every 4 years.

Unfortunately, it's still too dim to see with the unaided eye, but

skilled amateur astronomers with telescopes watching the southern

skies have spotted it. Toutatis won't get this close again until

2562.

 

Full Story - Today, September 29, 2004, is undisputedly the Day of

Toutatis, the famous "doomsday" asteroid.

 

Not since the year 1353 did this impressive "space rock" pass so

close by the Earth as it does today. Visible as a fast-moving faint

point of light in the southern skies, it approaches the Earth to

within 1,550,000 km, or just four times the distance of the Moon.

 

Closely watched by astronomers since its discovery in January 1989,

this asteroid has been found to move in an orbit that brings it

close to the Earth at regular intervals, about once every four

years. This happened in 1992, 1996, 2000 and now again in 2004.

 

Radar observations during these passages have shown that Toutatis

has an elongated shape, measuring about 4.6 x 2.4 x 1.9 km. It

tumbles slowly through space, with a rotation period of 5.4 days.

 

The above images of Toutatis were taken with the ESO Very Large

Telescope (during a technical test) in the evening of September 28.

They were obtained just over 12 hours before the closest approach

that happens today at about 15:40 hrs Central European Summer Time

(CEST), or 13:40 hrs Universal Time (UT). At the time of these

observations, Toutatis was about 1,640,000 km from the Earth, moving

with a speed of about 11 km/sec relative to our planet.

 

They show the asteroid as a fast-moving object of magnitude 10,

about 40 times fainter than what can be perceived with the unaided,

dark-adapted eye. They also prove that Toutatis is right on track,

following exactly the predicted trajectory in space and passing the

Earth at a safe distance, as foreseen.

 

Detailed calculations, taking into account all available

observations of this celestial body, have shown that although

Toutatis passes regularly near the Earth, today's passage is the

closest one for quite some time, at least until the year 2562. The

ESO observations, obtained at a moment when Toutatis was very close

to the Earth, will help to further refine the orbital calculations.

 

The "parallax effect" demonstrated!

Simultaneous images obtained with telescopes at ESO's two

observatories at La Silla and Paranal demonstrate the closeness of

Toutatis to the Earth. As can be seen on the unique ESO PR Photo

28e/04 that combines two of the exposures from the two

observatories, the sighting angle to Toutatis from the two

observatories, 513 km km apart, is quite different. Astronomers

refer to this effect as the "parallax". The closer the object is,

the larger is the effect, i.e., the larger will be the shift of the

line-of-sight.

 

Interestingly, the measured angular distance in the sky of the

beginnings (or the ends) of the two trails (about 40 arcsec),

together with the known distance between the two observatories and

the position of Toutatis in the sky at the moment of the exposures

fully define the triangle "Paranal-Toutatis-La Silla" and thus allow

to calculate the exact distance to the asteroid.

 

It is found to be very close to that predicted from the asteroid's

position in its orbit and that of the Earth at the moment of this

unique observation, 1,607,900 km. This exceptional, simultaneous set

of observations thus provides an independent measurement of

Toutatis' distance in space and, like the measured positions, a

confirmation of its computed orbit.

 

More information about Toutatis is available at the dedicated

webpage by the French discoverers and also at the specialised Near-

Earth Objects - Dynamic Site.

http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?objects:Toutatis;main