Now’s your best chance to view Mercury

The month of October is going to be particularly kind to astronomy enthusiasts this year, with Jupiter, Mars, and Venus set to draw unusually close to each other in the night sky, and the tricky-to-spot Mercury scheduled to make a rare bright appearance in the Northern Hemisphere.

You don’t get this kind of show for free though – over the next three weeks, the best time to view Mercury will be at around 5:45am (ET), with Jupiter, Mars, and Venus expected to switch up their positions relative to each other every morning. So best set your alarm and get ready to tell your tired body it’s all for science.

The first morning of note is Friday October 17, when Jupiter will finally catch up to Mars in the east so they’re just 0.5 degrees apart – as Joe Rao at points out, that’s about the width of the Moon in our night sky. This will be the first such conjunction between these two planets since 22 July 2013, and it’ll be the last till 7 January 2018.

During the week of October 22 to 29, Venus will join the party, and the three planets will align, with just 5 degrees between them. “That’s a big deal, because the next planetary trio won’t occur again until January 2021,” Bruce McClure and Deborah Byrd report for

Jupiter, Mars, and Venus will be closest together early in the morning on October 26, with Jupiter having such a close encounter with Venus, they’ll form what’s known as a ‘double planet’ for about 3 hours. “Another grouping of three planets won’t happen again until 10 January 2021,” say McClure and Byrd.

If that’s not enough to get you up in the (very early) morning, perhaps the opportunity to catch a glimpse of Mercury will be.

“Mercury rises before the Sun all of this month and is surprisingly easy to see from now through Halloween,” advises. “All you have to do is just look well below and to the left of our three other morning planets and above the eastern horizon during morning twilight, from about 30 to 45 minutes before sunrise for a bright yellowish-orange ‘star’.”

October 16 is set to be the best morning for Mercury viewing for this entire year, with its position relative to the Sun – about 18-degrees to the east of it – causing the light reflected off its surface to increase dramatically over the next couple of days, making it easy to see with the naked eye. And if you miss that one, on October 30, Mercury will be brighter than any star in the sky, except the brightest of them all, Sirius.

If planets aren’t your thing (wait, what? who are you?) from October 20 to 22, you can view the incredible Orionids Meteor Shower. The shower will occur throughout October, but on the night of October 21 and the morning of October 22, it will hit its peak, often delivering around 20 meteors per hour. It’s made up of the dust trails left behind by comet Halley.

Happy sky watching!

Source: Now’s your best chance to view Mercury – here’s how

Now’s your best chance to view Mercury

How Earth looks from outer space

If you were looking with the eye alone, how far away in space would our planet Earth still be visible?

Here is Earth from 900 million miles away, from the vantage point of the rings of Saturn.  Image via the Cassini spacecraft, which has been orbiting Saturn since 2004.

How far away from Earth can we be, to see it still with our own eyes?

To answer this question, you have to take into account how brightly Earth reflects sunlight. And the sun itself is an important factor. As seen from any great distance, Earth appears right next to the sun – and, from a great distance, the glare of our local star would make Earth difficult or impossible to see. But spacecraft exploring our solar system have given us marvelous views of Earth. So imagine blasting off and being about 300 kilometers – about 200 miles – above Earth’s surface. That’s the height at which the International Space Station (ISS) orbits. The surface of the Earth looms large in the window of ISS. In the daytime, you can clearly see major landforms. At night, you see the lights of Earth’s cities.

Earth in daylight, from ISS in 2012. The U.S. Great Lakes shine in the sun.  Read more about this image.

ng at an altitude of about 240 miles over the eastern North Atlantic, the Expedition 30 crew aboard the International Space Station photographed this nighttime scene. This view looks northeastward. Center point coordinates are 46.8 degrees north latitude and 14.3 degrees west longitude. The night lights of the cities of Ireland, in the foreground, and the United Kingdom, in the back and to the right, are contrasted by the bright sunrise in the background. The greens and purples of the Aurora Borealis are seen along the rest of the horizon. This image was taken on March 28, 2012.

As you pass the moon – about 380,000 kilometers away – or a quarter million miles – Earth looks like a bright ball in space – not very different from the way the moon looks to us. The first images of the Earth from the moon came from the Apollo mission. Apollo 8 in 1968 was the first human spaceflight to leave Earth orbit. It was the first earthly spacecraft to be captured by and escape from the gravitational field of another celestial body, in this case the moon. It was the first voyage in which humans visited another world and returned to return to Earth.

Then came the mind-blowing moment of seeing both the Earth and moon together in space. The next picture shows a crescent-shaped Earth and moon – the first of its kind ever taken by a spacecraft – on September 18, 1977. NASA’s Voyager 1 spacecraft was 7.25 million miles (11.66 million kilometers) from Earth at the time.

Now moon exploration has become more common, though still amazing. This mosaic below shows images of Earth and the moon acquired by the multispectral imager on the Near Earth Asteroid Rendezvous Spacecraft (NEAR) on January 23, 1998, 19 hours after the spacecraft swung by Earth on its way to the asteroid 433 Eros. The images of both were taken from a range of 250,000 miles (400,000 kilometers), approximately the same as the distance between the two bodies.

This mosaic shows images of Earth and the moon acquired by the multispectral imager on the Near Earth Asteroid Rendezvous Spacecraft (NEAR) on January 23, 1998, 19 hours after the spacecraft swung by Earth on its way to the asteroid 433 Eros. The images of both were taken from a range of 250,000 miles (400,000 kilometers), approximately the same as the distance between the two bodies.  Read more about this image.

The robotic Kaguya spacecraft orbited around Earth’s moon in 2007. Launched by Jpan, and officially named the Selenological and Engineering Explorer (SELENE), studied the origin and evolution of the moon. The frame below is from Kaguya’s onboard HDTV camera.

The robotic Kaguya spacecraft orbited around Earth's moon in 2007. Japan launched this scientific mission of the Selenological and Engineering Explorer (SELENE), nicknamed Kaguya, in order to study the origin and evolution of the moon. This frame is from Kaguya's onboard HDTV camera.

Another image from ___, which captured the Japanese craft got footage and stills of Earth setting.  Remember that, if you were on the moon, you would not see Earth rise or set.  But spacecraft in orbit around the moon do experience this scene.

Speeding outward from the Earth and moon system, you pass the orbits of the planets Mars, Jupiter, Saturn, Uranus and Neptune. From all of these worlds, Earth looks like a star – which gets fainter as you get farther away. From the world next door, though, Mars, a human observer with normal vision could easily see Earth and the moon as two distinct, bright evening or morning “stars.”

Earth and moon, as seen from Mars by the Curiosity rover on January 31, 2014.  Read more about this image.

This is the famous image known as Pale Blue Dot.  It's a photograph of Earth taken on February 14, 1990, by the Voyager 1 space probe from a record distance of about 6 billion kilometers (3.7 billion miles).

The light from Earth finally becomes too faint to see with the eye alone at around 14 billion kilometers – about 9 billion miles – from home – around the outer limit of our solar system – nowhere near as far as even the next-nearest star. Of course, if an astronaut or alien had a telescope, he or she could definitely see Earth further away than that.

Bottom line: How far away in space can you view Earth with the eye alone? About as far away as the outer reaches of our own solar system at about 14 billion kilometers – about 9 billion miles – from home.

Source: How Earth looks from outer space

How Earth looks from outer space

NASA Selects Mission Science Instruments Searching for Habitability of Jupiter’s Ocean Moon Europa

The fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution.  Credits: NASA/JPL-Caltech/SETI Institute

In a major move forward on a long dreamed of mission to investigate the habitability of the subsurface ocean of Jupiter’s mysterious moon Europa, top NASA officials announced today, Tuesday, May 26, the selection of nine science instruments that will fly on the agency’s long awaited planetary science mission to an intriguing world that many scientists suspect could support life.

“We are on our way to Europa,” proclaimed John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington, at a media briefing today outlining NASA’s plans for a mission dedicated to launching in the early to mid-2020s. “It’s a mission to inspire.”

“We are trying to answer big questions. Are we alone?”

“The young surface seems to be in contact with an undersea ocean.”

The Europa mission goal is to investigate whether the tantalizing icy Jovian moon, similar in size to Earth’s moon, could harbor conditions suitable for the evolution and sustainability of life in the suspected ocean.

It will be equipped with high resolution cameras, radar and spectrometers, several generations beyond anything before to map the surface in unprecedented detail and determine the moon’s composition and subsurface character. And it will search for subsurface lakes and seek to sample erupting vapor plumes like those occurring today on Saturn’s tiny moon Enceladus.

“Europa has tantalized us with its enigmatic icy surface and evidence of a vast ocean, following the amazing data from 11 flybys of the Galileo spacecraft over a decade ago and recent Hubble observations suggesting plumes of water shooting out from the moon,” says Grunsfeld.

“We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth.”

Planetary scientists have long desired a speedy return on Europa, ever since the groundbreaking discoveries of NASA’s Galileo Jupiter orbiter in the 1990s showed that the alien world possessed a substantial and deep subsurface ocean beneath an icy shell that appears to interact with and alter the surface in recent times.

This 12-frame mosaic provides the highest resolution view ever obtained of the side of Jupiter's moon Europa that faces the giant planet. It was obtained on Nov. 25, 1999 by the camera onboard the Galileo spacecraft, a past NASA mission to Jupiter and its moons. Credit: NASA/JPL/University of Arizona

NASA’s Europa mission would blastoff perhaps as soon as 2022, depending on the budget allocation and rocket selection, whose candidates include the heavy lift Space Launch System (SLS).

The solar powered probe will go into orbit around Jupiter for a three year mission.

“The mission concept is that it will conduct multiple flyby’s of Europa,” said Jim Green. director, Planetary Science Division, NASA Headquarters, during the briefing.

“The purpose is to determine if Europa is a habitable place. It shows few craters, a brown gum on the surface and cracks where the subsurface meet the surface. There may be organics and nutrients among the discoloration at the surface.”

Europa is at or near the top of the list for most likely places in our solar system that could support life. Mars is also near the top of the list and currently being explored by a fleet of NASA robotic probes including surface rovers Curiosity and Opportunity.

“Europa is one of those critical areas where we believe that the environment is just perfect for potential development of life,” said Green. “This mission will be that step that helps us understand that environment and hopefully give us an indication of how habitable the environment could be.”

The exact thickness of Europa’s ice shell and extent of its subsurface ocean is not known.

The ice shell thickness has been inferred by some scientists to be perhaps only 5 to 10 kilometers thick based on data from Galileo, the Hubble Space Telescope, a Cassini flyby and other ground and space based observations.

The global ocean might be twice the volume of all of Earth’s water. Research indicates that it is salty, may possess organics, and has a rocky sea floor. Tidal heating from Jupiter could provide the energy for mixing and chemical reactions, supplemented by undersea volcanoes spewing heat and minerals to support living creatures, if they exist.

This artist's rendering shows a concept for a future NASA mission to Europa in which a spacecraft would make multiple close flybys of the icy Jovian moon, thought to contain a global subsurface ocean.  Credits: NASA/JPL-Caltech

“Europa could be the best place in the solar system to look for present day life beyond our home planet,” says NASA officials.

The instruments chosen today by NASA will help answer the question of habitability, but they are not life detection instruments in and of themselves. That would require a follow on mission.

“They could find indications of life, but they’re not life detectors,” said Curt Niebur, Europa program scientist at NASA Headquarters in Washington. “We currently don’t even have consensus in the scientific community as to what we would measure that would tell everybody with confidence this thing you’re looking at is alive. Building a life detector is incredibly difficult.”

‘During the three year mission, the orbiter will conduct 45 close flyby’s of Europa,” Niebur told Universe Today. “These will occur about every two to three weeks.”

The close flyby’s will vary in altitude from 16 miles to 1,700 miles (25 kilometers to 2,700 kilometers).

“The mass spectrometer has a range of 1 to 2000 daltons, Niebur told me. “That’s a much wider range than Cassini. However there will be no means aboard to determine chirality.” The presence of Chiral compounds could be an indicator of life.

Right now the Europa mission is in the formulation stage with a budget of about $10 million this year and $30 Million in 2016. Over the next three years the mission concept will be defined.

The mission is expected to cost in the range of at least $2 Billion or more.

Jupiter Moon Europa, Ice Rafting View

Here’s a NASA description of the 9 instruments selected:

Plasma Instrument for Magnetic Sounding (PIMS) — principal investigator Dr. Joseph Westlake of Johns Hopkins Applied Physics Laboratory (APL), Laurel, Maryland. This instrument works in conjunction with a magnetometer and is key to determining Europa’s ice shell thickness, ocean depth, and salinity by correcting the magnetic induction signal for plasma currents around Europa.

Interior Characterization of Europa using Magnetometry (ICEMAG)
— principal investigator Dr. Carol Raymond of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California. This magnetometer will measure the magnetic field near Europa and – in conjunction with the PIMS instrument – infer the location, thickness and salinity of Europa’s subsurface ocean using multi-frequency electromagnetic sounding.

Mapping Imaging Spectrometer for Europa (MISE)
— principal investigator Dr. Diana Blaney of JPL. This instrument will probe the composition of Europa, identifying and mapping the distributions of organics, salts, acid hydrates, water ice phases, and other materials to determine the habitability of Europa’s ocean.

Europa Imaging System (EIS) — principal investigator Dr. Elizabeth Turtle of APL. The wide and narrow angle cameras on this instrument will map most of Europa at 50 meter (164 foot) resolution, and will provide images of areas of Europa’s surface at up to 100 times higher resolution.

Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) — principal investigator Dr. Donald Blankenship of the University of Texas, Austin. This dual-frequency ice penetrating radar instrument is designed to characterize and sound Europa’s icy crust from the near-surface to the ocean, revealing the hidden structure of Europa’s ice shell and potential water within.

Europa Thermal Emission Imaging System (E-THEMIS) — principal investigator Dr. Philip Christensen of Arizona State University, Tempe. This “heat detector” will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites, such as potential vents erupting plumes of water into space.

MAss SPectrometer for Planetary EXploration/Europa (MASPEX) — principal investigator Dr. Jack (Hunter) Waite of the Southwest Research Institute (SwRI), San Antonio. This instrument will determine the composition of the surface and subsurface ocean by measuring Europa’s extremely tenuous atmosphere and any surface material ejected into space.

Ultraviolet Spectrograph/Europa (UVS) — principal investigator Dr. Kurt Retherford of SwRI. This instrument will adopt the same technique used by the Hubble Space Telescope to detect the likely presence of water plumes erupting from Europa’s surface. UVS will be able to detect small plumes and will provide valuable data about the composition and dynamics of the moon’s rarefied atmosphere.

SUrface Dust Mass Analyzer (SUDA) — principal investigator Dr. Sascha Kempf of the University of Colorado, Boulder. This instrument will measure the composition of small, solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys.

Source: NASA Selects Mission Science Instruments Searching for Habitability of Jupiter’s Ocean Moon Europa

NASA Selects Mission Science Instruments Searching for Habitability of Jupiter’s Ocean Moon Europa