New research on the Antennae Galaxies using the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope shows that this benchmark pair of interacting galaxies is in fact much closer than previously thought - 45 million light-years instead of 65 million light-years.

The Antennae Galaxies are among the closest known merging galaxies. The two galaxies, also known as NGC 4038 and NGC 4039, began interacting a few hundred million years ago, creating one of the most impressive sights in the night sky. They are considered by scientists as the archetypal merging galaxy system and are used as a standard against which to validate theories about galaxy evolution.

Aureum Chaos is a 368 kilometer (229 mile) wide area of chaotic terrain in the eastern part of Valles Marineris. The chaotic terrain is thought to have formed by collapse of the surrounding Margaritifer Terra highland region. Aureum Chaos contains heavily eroded, randomly oriented mesas, plateaus, and knobs -- many revealing distinct layered deposits along their slopes.

These deposits may be formed from remnants of the collapsed highlands, sand carried by Martian winds, dust or volcanic ash that settled out of the atmosphere, or sediments laid down on the floor of an ancient lake.

Sebastien Bouquillon (SYRTE/Obs. de Paris), Ricky Smart (INAF/OATo, Torino) and Alexandre Andrei (Observatorio Nacional, Rio de Janeiro) have used the 2.2m telescope of the European Southern Observatory at La Silla, Chile, to take several photographs of NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite in its orbit, which is about 1.5 million kilometres from Earth.

Perhaps surprisingly, they did so as part of the preparations for ESA's Gaia mission, which scientifically is totally unrelated to WMAP.

The Ulysses mission operations team has won an international award in recognition of their outstanding contributions to the success and scientific productivity of the joint ESA/NASA observatory mission, now orbiting the poles of the Sun.

The ESA/NASA Ulysses team was tapped to receive the 2008 'International SpaceOps Award for Outstanding Achievement' by the International Committee on Technical Interchange for Space Mission Operations and Ground Data Systems, also known as the SpaceOps Committee. The award will be presented during the SpaceOps 2008 Conference, taking place from 12 to 16 May in Heidelberg, Germany.

Two decades of scrutinizing Saturn are finally paying off, as scientists have discovered a wave pattern, or oscillation, in Saturn's atmosphere only visible from Earth every 15 years.

The discovery of the wave pattern is the result of a 22-year campaign observing Saturn from Earth (the longest study of temperature outside Earth ever recorded), and the Cassini spacecraft's observations of temperature changes in the giant planet's atmosphere over time.

New scientific evidence suggests that deep inside the planet Mercury, iron "snow" forms and falls toward the center of the planet, much like snowflakes form in Earth's atmosphere and fall to the ground.

The movement of this iron snow could be responsible for Mercury's mysterious magnetic field, say researchers from the University of Illinois and Case Western Reserve University. In a paper published in the April issue of the journal Geophysical Research Letters, the scientists describe laboratory measurements and models that mimic conditions believed to exist within Mercury's core.

The following new images taken by the High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter spacecraft are now available:

• Rayed Crater in Tharsis Region
  This image shows a small rayed impact crater, about 160 meters (530 feet) in diameter, in the Tharsis region in the northern hemisphere of Mars.


• Lava Stratigraphy in the Flanks of Olympus Mons
  This HiRISE image captures a small part of the giant scarp that marks the base of Olympus Mons, the largest volcano in the solar system.


• Eroded Crater Slopes in Ancient Noachis Region
  This image covers the southern slope of an old impact crater inside a larger and still older crater, in the Martian highlands.


• Changing Frost Patterns in Louth Crater
  This image shows the changing seasonal frost patterns on Louth Crater, located at latitude 70 N.


• Jointed Rocks Near Nilosyrtis Mensae
  This image shows a part of the floor of a large, heavily modified crater in the Nilosyrtis Mensae region.


• Frosted Crater Near Mars' North Pole
  This image was taken over the north polar region of Mars, just south of the layered ice cap.


• Layered Rock in Noctis Labyrinthus
  This scene is the floor of a trough in Noctis Labryinthus, a region of chaotic terrain located between the Tharsis Rise and Valles Marineris.


• Mantled Craters in Terra Cimmeria
  This image shows the intersection of two overlapping craters, although it is unknown which of the two formed first.

NASA's Phoenix Mars Lander is scheduled to land on the Martian northern plains near 68° north latitude, 127° west longitude on May 25, 2008.

In preparation for the landing, NASA's Mars Reconnaissance Orbiter has been monitoring weather in the region around the landing site. On April 20, 2008, the orbiter's Context Camera captured this view showing two active dust devils within the Phoenix landing ellipse.

ESA's orbiting X-ray observatory XMM-Newton has been used by a team of international astronomers to uncover part of the missing matter in the universe.

10 years ago, scientists predicted that about half of the missing 'ordinary' or normal matter made of atoms exists in the form of low-density gas, filling vast spaces between galaxies.

Opportunity is healthy and all subsystems are performing as expected, with the exception of the Instrument Deployment Device (the robotic arm). Power has improved slightly during the last week, primarily as the result of a better state of charge in the batteries.

Given the recent difficulties with the robotic arm, the rover hasn't been using the batteries as much as usual. Energy has averaged about 380 watt-hours (almost enough energy to light four 100-watt bulbs for one hour).

Titan and Earth have much in common, but not when it comes to sand. On Earth, sand grains form by breaking things down, but on Titan, the opposite may be true - with much of the sand a product of building things up.

That's one theory Cassini scientists are considering after studying Titan's massive sand dunes with the visible and infrared mapping spectrometer on the Cassini Saturn orbiter. The new observations raise the possibility that much of the sand grows from hydrocarbon particulates fallen from the sky that, once on the ground, join together and become sand grain-size particles.

The Johns Hopkins University Applied Physics Laboratory is sending a spacecraft closer to the sun than any probe has ever gone - and what it finds could revolutionize what we know about our star and the solar wind that influences everything in our solar system.

NASA has tapped APL to develop the ambitious Solar Probe mission, which will study the streams of charged particles the sun hurls into space from a vantage point within the sun's corona -- its outer atmosphere -- where the processes that heat the corona and produce solar wind occur.

The following new images taken by the Imaging Science Subsystem (ISS) on the Cassini spacecraft are now available:

• F Ring Informants (Released 21 April 2008)
  Ever-changing kinks and wiggles define Saturn's dynamic F ring.
  


• The Orbiting Fleet (Released 22 April 2008)
  A fleet of small moons patrols the outskirts of Saturn's icy rings.
  


• Ring Escort (Released 23 April 2008)
  Pandora loops around Saturn, confining the narrow F ring as it goes.
  


• Scrambled Edge (Released 1 May 2008)
  The outer edge of Saturn's A ring displays intriguing structure in this Cassini spacecraft view.
  


• Beauty Marks (Released 2 May 2008)
  Two dark spots drift across the northern skies of Saturn.

The following new images taken by the Thermal Emission Imaging System (THEMIS) on the Mars Odyssey spacecraft are now available:

• Triplet Crater (Released 28 April 2008)
  It is not uncommon for multiple pieces of a meteor to impact Mars close together at the same time.
  


• Landslide (Released 29 April 2008)
  A landslide deposit is visible in this image of an unnamed crater in Terra Cimmeria.
  


• Granicus Valles (Released 30 April 2008)
  Granicus Valles originates from fracture systems of the Elysium Volcanic Complex.
  


• Elysium Planitia (Released 1 May 2008)
  This interesting surface texture is located in Elysium Planitia.
  


• Ridges (Released 2 May 2008)
  Intersecting ridges create an unusual surface in this region of Noachis Terra.

When it comes to giving birth, galaxies don't seem to have a "ticking biological clock."

In fact, observations from NASA's Spitzer Space Telescope show that old galaxies were the biggest producers of new stars when our universe was half of its current age of 13.6 billion years.