Drawing of the path of near-Earth asteroid 2012ge DA14 when it passes close to Earth on Feb. 15, 2013. (NASA)

Earth is about to have a close encounter with an asteroid, the nearest an object of its size has ever come to our planet.

The fly-by is expected to occur at around 1924 UTC on Feb. 15, according to scientists at NASA’s Jet Propulsion Laboratory.

The US space agency says there’s no chance the asteroid will collide with Earth.

“This is a record-setting close approach,” says Don Yeomans of NASA’s Near Earth Object Program at JPL. “Since regular sky surveys began in the 1990s, we’ve never seen an object this big get so close to Earth.”

Scientists expect the asteroid to pass us at a distance of about 27,700 km from the surface of the Earth. That’s close enough for it to pass inside the ring of a number of geosynchronous weather and communications satellites currently orbiting the Earth at about 36,000 km from Earth’s surface above the equator.

However, the asteroid should fly well above most of the satellites and spacecraft circling the planet, including the International Space Station (ISS).

To get an idea of just how close the 2012 DA14 asteroid will get to us, consider that it will come nearer to us than the moon, about 1/13th of the distance to the Moon, which is 384,400 km from Earth.

It’s expected to whiz by our planet quite fast, at a speed of about 7.8 kilometers per second in a south-to-north direction. This will be the closest an asteroid has come to Earth in at least 30 years and will give researchers a unique opportunity  to study it.

The 2012 DA14 is quite small, weighing about 130,000 metric tons and measuring about 45 meters across, less than the width of a soccer field. Astronomers believe it is made of stone, rather than metal or ice.

The asteroid was discovered by astronomers at the OAM Observatory in La Sagra, Spain less than a year ago, on Feb. 23, 2012, which is why “2012″ is part of its name.

NASA video feature of asteroid fly-by

A few other asteroids have flown even closer to Earth, but they were much smaller than the one expected to zoom by this month.  Scientists say objects of this size fly this close to the Earth about once every 40 years; an actual collision with Earth happens about every 1,200 years.

The 2012 DA14 asteroid is so tiny, it’s expected to look like a small point of light, even to those using the biggest optical telescopes. Difficult to see with the naked eye, it will be easily visible with a good set of binoculars or a small telescope.

Astronomers say the best place to see the asteroid will be in Indonesia, but people in Eastern Europe, Asia and Australia should also be able to get a glimpse.

The public can watch the event through live feeds from telescopes in La Sagra and Tenerife, Spain.

NASA astronomers at the Goldstone Deep Space Communications Complex (GDSCC) in California’s Mojave Desert will use radar imaging to determine the orbit of the asteroid, allowing them to better predict future encounters. The imaging data will also be used to create a 3D map showing the asteroid from all sides and should reveal more about the asteroid’s physical characteristics, such as its size and spin.

(Photo: NASA, M.Masetti)

If you think you have what it takes to build a satellite, NASA has just introduced an online game that might appeal to you.

With “Build It Yourself: Satellite!” the US space agency offers users the chance to act as engineers and astronomers who conceive and build their own special virtual satellite.

“It’s fun to play,” says Maggie Masetti, a NASA webmaster who created the game. “And users will learn something about satellite instrumentation and optics and how they are used to make scientific discoveries, as well about a large range of different existing astronomical missions.”

The game lets players choose what kind of science their satellite will study. They can then customize the sophisticated technical aspects of their satellite – such as what wavelengths their creation will operate at and what kind of tools, instruments and optics will give them the best opportunity to learn as much as possible about their chosen science.

Artist conception of James Webb Space Telescope (Image: NASA)

A number of astronomical missions, some dating back to 1980s, are available to game players.  You can go from rather small x-ray telescopes, like NASA’s Rossi X-ray Timing Explorer, to the much larger and popular  Hubble Space Telescope.

The game is available in two sizes so players can choose the one better suited to their monitor.  If you’re stuck with a slower computer, the game offers a special toggle button that will reduce the quality of the graphics but will make the game run faster.

The new gaming experience was inspired by the James Webb space telescope, which is being built now and is scheduled for launch in 2018.

Said to have the latest cutting-edge technology, the Webb space telescope will help scientists expose the secrets of the universe by taking them far back in time, toward the Big Bang.  Webb will be the most powerful telescope ever built by the space agency.

Who knows, maybe after playing “Build It Yourself: Satellite!” you’ll realize you have the talent and ability to become a real-life rocket scientist!

Time-lapse of the construction of the giant structural steel frame that will be used to assemble the mirrors and instruments of the James Webb Space Telescope.

S/2010 J 1 in motion Sept. 8, 2010. Animation is sped up by a factor of 2000. The actual time between each image in the animation is roughly 38 minutes. (Photo:Canada-France-Hawaii Telescope)

Astronomers have found that one of two recently-discovered moons of Jupiter is just two kilometers in diameter and may be the smallest of Jupiter’s 67 satellites.

Back in September 2010, scientists discovered two unknown distant satellites of Jupiter while conducting routine tracking observations of the planet’s previously identified moons.

To confirm that these were indeed new satellites of Jupiter, and not asteroids, the scientists re-observed them several more times during the autumn of 2010.

The International Astronomical Union’s Minor Planet Center designated the two new moons as S/2010 J 1 and S/2010 J 2.

S/2010 J 1 was discovered in September 2010 from images taken with the Palomar Observatory’s 200-inch Hale Telescope.  At its furthest, this moon is about 30,774,922 kilometers from Jupiter.

The second moon, S/2010 J 2, about 26,541,445 kilometers from the giant planet, was discovered the same month on images taken with the MegaCam mosaic CCD camera by the 3.6m Canada-France-Hawaii telescope (CFHT).  After checking observational data, astronomers also later found that the satellite was weakly visible, on Sept 7, 2010, at the Palomar Observatory.

It’s interesting to note that the moon that would come to be called S/2010 J 1, was first detected back in 2003, but was never classified as a satellite because it couldn’t be found in required follow-up observations.

The astronomers say the size of the two moons can be estimated on factors that are based on their brightness.  S/2010 J 1 is estimated to be around three kilometers in diameter. S/2010 J 1, the faintest and probably smallest Jovian moon, has been estimated to be about two kilometers in diameter.

Red diamonds show the 2010-11 observed locations of S/2010 J 1, while blue triangles show the locations of S/2010 J 2. The predicted positions of the satellites for the best fit orbits from JPL are plotted at 48-hour intervals, shown by the red and blue dots for S/2010 J 1 and S/2010 J 2, respectively (Courtesy: Mike Alexandersen)

S/2010 J 1 and S/2010 J 2 are designated as irregular satellites, or provisional moons, and are not given actual names by the International Astronomy Union (IAU) because their discoveries have not been confirmed.

Moons such as the S/2010 J 1 and S/2010 J 2 have been found to be clustered in families of other satellites with similar colors and orbits. Scientists believe these families may have formed as a result of ancient collisions with comets or asteroids with former larger moons.

S/2010 J 1 appears to belong to the Carme group, or family, while S/2010 J 2 appears to belong to the Ananke group.