AMATEUR ASTRONOMY:

WHAT WAS EARLY MARS LIKE?:

Evidence is accumulating that the planet Mars was quite wet in its early life. does this means that it once was home to life ? Here's an article from Space.Com about the latest findings about water on early Mars.

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Early Mars Was All Wet

By Andrea Thompson

A lot more Martian rocks were altered by water than scientists originally thought, suggesting that early Mars was a very wet place.

New observations made by NASA's Mars Reconnaissance Orbiter (MRO), currently circling the planet, have revealed evidence that vast regions of the southern highlands of Mars were altered by water in a variety of environments billions of years ago.

Water is a key condition for life as we know it. Though there is no firm evidence that Mars has ever harbored life, knowing that the planet was once wet suggests that it was at least habitable in the past.

The key to the finding is the discovery that rocks called phyllosilicates are widespread on at least the planet's southern hemisphere. The water present on Mars from about 4.6 billion to 3.8 billion years ago transformed some rocks into these phyllosilicates, which include clays rich in iron, magnesium or aluminum, mica, and kaolinite (an ingredient in Kaopectate).

"In a phyllosilicate, the atoms are stacked up into layers, and all of the phyllosilicates have some sort of water or hydroxyl [oxygen and hydrogen group] incorporated into the crystal structure," said study team member Scott Murchie of Johns Hopkins University.

Previous data from an instrument called OMEGA - Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activite on the Mars Express spacecraft had revealed only a few large outcrops of phyllosilicates, suggesting they were a relative rarity on Mars.

"It sort of gave the false impression that rocks that were altered like this were more restricted than they really are," Murchie said.

But the new observations, made with MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and detailed in the July 17 issue of the journal Nature, reveal "thousands and thousands of outcrops that we can now resolve with the higher resolution of the instrument, and they're scattered all over the planet wherever the older rocks occur," Murchie told SPACE.com.

"What that's suggesting to us is that we're seeing a pervasive subsurface layer that goes back in time — it's been altered by water to clays and related minerals, and it's outcropping all over the place," Murchie added.

The layer of water-altered rocks sits below younger, volcanic rocks and the ubiquitous windblown Martian dust and sand in many places. But in craters and scarps, including Valles Marineris, across the terrain of the southern hemisphere, the ancient clays and other minerals have been exposed.

"It's like going to the bottom rock layer in the Grand Canyon," Murchie said, where ancient layers underlie the whole area, but are only exposed in a few places.

This layering gives scientists a dividing line of about 3.7 to 3.5 billion years ago for a transition in Martian geology: "Before that the rocks were altered into clays, since then they're not," Murchie said.

The variety of clays and other minerals formed also tells scientists that rock was altered by water under a variety of conditions.

"There's a variety of environments that are formed where the rock was lightly altered where you see things like chlorite, to where it was altered with water at really high temperature, where you see mica, to where a lot of water must have flowed through the rock in order to dissolve out the iron and magnesium and you're left with kaolinite," Murchie said.

The alteration of later rocks, such as the sulfates found by the Mars Exploration Rovers (MER), Spirit and Opportunity in the northern hemisphere, on the other hand, formed under much more restricted conditions.

One implication of these findings is that some of the environments that formed the phyllosilicates would not have been antagonistic to any potential life, unlike the conditions that formed the sulfates, which formed in a highly acidic environment similar to battery acid, as Murchie put it.

Whether the MER rovers can get a close-up peek at these phyllosilicates while the robots still roam the Martian surface is uncertain, Murchie said, because so far the rocks haven't been detected near the crafts. But they could be there and simply be obscured in the north from the MRO instruments by dust.

"It doesn't take much to hide something from our optical instrument in orbit," he said, just a few micrometers of dust. "So just brushing away the rock surface could be enough," he added.
Whether or not Spirit and Opportunity get a chance to investigate these intriguing rocks up close, future rover missions, such as the Mars Science Laboratory set to launch 2009, could certainly be aimed at known phyllosilicate-rich sites, Murchie said, shedding more light on the mysteries of early Mars.
Video Player: Mars Reconnaissance Orbiter
Get to Know MRO: Top 10 Facts About NASA's Mars Reconnaissance Orbiter
Zoom In: Water on Mars??

AMATEUR ASTRONOMY:

THE RESURRECTION OF "PLANET X":

The search for planets beyond the traditional 6 visible planets has usually been guided by observations of gravitational anomalies. From the hypothetical Vulcan, supposedly orbiting between Mercury and the Sun and consigned to oblivion by Einstein's theory of relativity to the discovery of Neptune (1846) and Pluto (1930) this general picture has held true, even if the previous discovery of Uranus (first observation 1690 and description as a planet in 1781) was made by regular observation. Today the discovery of trans-Plutonian objects such as Sedna- relies more on regular observation once more. The long standing quest for "Planet X" has pretty well fallen by the wayside since the discovery of Pluto and the explaining of orbital anomalies that Pluto couldn't account for. The existence or non-existence of the presumed red or brown dwarf companion of the Sun nicknamed 'Nemesis' (because of its hypothetical role in mass extinctions) remains an open question. But now it seems that the quest for Planet X has opened up once again, not because of planetary orbitals but because of features of the Kuiper Belt in which Pluto and Sedna orbit. Here's the story from Space.Com. Keep on dreaming sci-fi fans.

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Large 'Planet X' May Lurk Beyond Pluto

An icy, unknown world might lurk in the distant reaches of our solar system beyond the orbit of Pluto, according to a new computer model.

The hidden world -- thought to be much bigger than Pluto based on the model -- could explain unusual features of the Kuiper Belt, a region of space beyond Neptune littered with icy and rocky bodies. Its existence would satisfy the long-held hopes and hypotheses for a "Planet X" envisioned by scientists and sci-fi buffs alike.

"Although the search for a distant planet in the solar system is old, it is far from over," said study team member Patryk Lykawka of Kobe University in Japan.

The model, created by Lykawka and Kobe University colleague Tadashi Mukai, is detailed in a recent issue of Astrophysical Journal.

If the new world is confirmed, it would not be technically a planet. Under a controversial new definition adopted by the International Astronomical Union (IAU) last week, it would instead be the largest known "plutoid."

The Kuiper Belt contains many peculiar features that can't be explained by standard solar system models. One is the highly irregular orbits of some of the belt's members.

The most famous is Sedna, a rocky object located three times farther from the sun than Pluto. Sedna takes 12,000 years to travel once around the Sun, and its orbit ranges from 80 to 100 astronomical units (AU). One AU is equal to the distance between the Earth and the Sun.

According to the model, Sedna and other Kuiper Belt oddities could be explained by a world 30 to 70 percent as massive as Earth orbiting between 100 AU and 200 AU from the sun.

At that distance, any water on the world's surface would be completely frozen. However, it might support a subsurface ocean like those suspected to exist on the moons Titan and Enceladus, said Mark Sykes, director of the Planetary Science Institute in Arizona.

"The interesting thing for me is the suggestion of the kinds of very interesting objects that may yet await discovery in the outer solar system," said Sykes, who was not involved in the study. "We are still scratching the edges of that region of the solar system, and I expect many surprises await us with the future deeper surveys."

MARS RISING:

Presently the planet Mars rises in the east southeast about 2 hours before dawn in Aquarius. Its present magnitude of 1 makes it a dim object for viewing in the dawn twilight. In the coming weeks, however, Mars will be rising earlier and progressing into a darker part of the sky, making for better viewing. Throughout the year Mars will be rising progressively earlier until it reaches "opposition" next December. This is also the time when the orbit of the Earth overtakes the slower orbit of Mars and the planets are closest together. At that time Mars will have a magnitude of -1.6, brighter than Sirius. The planet will rise at sunset then and set at sunrise, being highest in the sky around midnight. The closest approach of Mars and the Earth will occur on Dec. 18th when the planets will be about 88 million kilometers apart. The "opposition" when Mars is directly opposite the Sun, rising and setting will actually occur on Christmas Eve. At that time the planet will be best for telescopic viewing.

Just a little heads up here. On August 27th Mars and Earth made a closer approach than they have in 60,000 years, and an email titled 'Mars Spectacular' made its rounds with claims such as Mars being brighter than the full Moon. Seems that every spring and summer the email reappears with its liberal use of exclamation marks. Ignore it. Mars will be better positioned for viewing in the months to come, but the email is a hoax.

MERCURY'S LIQUID CORE:

Mercury. The first planet from the sun, laying at a distance of 0.3871 au from Sol, about 1/3rd of the distance from the Sun to Earth. Mercury has a diameter of 4,878 km, once more about 1/3d of the diameter of Earth but a mass of only 5.53% that of our planet. Its gravity is only about 28.4% that of the Earth, and its year is only about 88 days. Its rotation, however, is slower. A Mercurian day is about 59 Earth days. It's this rotation that is important in the latest discovery about Mercury. As reported in the May 4th edition of Science magazine, the journal of the AAAS, a team of astronomers from Cornell University measured small twists in the planet's rotation. They did this by sending a radio signal to reflect off the planet from a station at Goldstone, California and catching the signal again at another station in Green Bank, West Virginia.Other signals were also sent from the Arecibo Observatory in Puerto Rico and analysed at Goldstone. Their conclusion after 5 years of observation was that their values were twice as large as they would be if Mercury's core was solid. Jean-Luc Margot of Cornell states that they have a 95% confidence level in their results which are best interpreted as the result of Mercury having at least a partially molten core.

This explains the results of the flyby of Mariner 10 thirty years ago which detected a small magnetic field around the planet, something that simply couldn't occur if the planet had a solid core. The speculation is that lighter elements such as sulphur are present in Mercury's core in amounts substantial enough to lower its melting point enough to produce a magma. This challenges the standard model of planet formation which says that the terrestrial planets such as Mars, Earth, Venus and Mercury formed from heavier elements with high melting points that condensed near to the Sun while the outer planets formed in zones where lighter elements could condense. The speculation that explains this anomaly is that there was some sort of "mixing" in the early solar system whereby planetesimals carrying lighter elements were transported into the inner solar system where they were part of planet formation.

Mercury will be studied further when NASA's Messenger spacecraft makes its first flyby in 2008.

Mercury (Greek- Hermes) was the messenger of the gods and patron of merchants, messengers, lawyers and thieves. Only the "messengers" don't fit in the above lot. It solar facing surface is about 400 degrees centigrade while the far side is -170 degrees. Worse than a Manitoba day. The very eccentric orbit of Mercury and its high variation in speed would produce some strange effects if you were standing on the surface (with nuclear sunblock of course). The Sun would be seen to rise, stop, back up and set in the east, rise again, move to the west, set again, rise in the west and finally set in the east. Seems like the Sun can't make up its mind.

Mercury presently cannot be viewed, but it will appear again in the evening sky after the sun sets in late May and early June.

SATURN SPOTTING:

The planet Saturn is presently making one of its retrograde motions and passing from the constellation of Leo westward to the faint constellation of Cancer. It previously passed to Leo from cancer last fall in Sept and Oct.. Looking down the alley from her city location Molly cannot distinguish any of the stars of Cancer, but she can easily make out most of the stars of Leo and at least Castor, Pollux, Tejat and Alhena in Gemini (the constellation immediately to the west of Cancer). Saturn is about 15 degrees to the west of Algiebra(the second star in the "hook" of Leo, and a bit further towards the zenith than the bright star Regulus (the beginning of the "hook"). Viewing is a bit restricted because of the light of the first quarter Moon. Tonight, at about 11:00 pm Central Standard Time, Leo and Saturn are a bit to the east of due south. Orion has begun to advance towards the horizon in the southwest. Sirius, the brightest star in the sky, is almost due south.

For further information on the planet Saturn go to the Wikipedia article and the Nine Planets site. The two sites complement each other.

A little interesting Saturn factoid. The actual length of a Saturnian day is uncertain. The gaseous nature of the planet leaves no firm "handle" to measure the period of rotation. Astronomers have relied on radio measurements of the planet's magnetic field to make their estimates, but recent findings have shown that geyser activity on the small Saturnian moon Encaledus inhibits the rotation of the planet's magnetic field to a speed less than that of the actual rotation. The most recent measurements place Saturn's "day" as about 10 hours and 47 minutes. Interestingly enough comparative measurements have shown that this is about 6 to 8 minutes longer than the time Saturn took to rotate in the 1980s when the first measurements were taken.

Anyways, more on Saturn, Leo and the other constellations mentioned later.

Molly