Scientists Find an #EarthTwin

An artist's concept of Kepler-186f, the first Earth-size planet found in the habitable zone, a range of distances from a star where liquid water could pool on an orbiting planet's surface. Credit NASA Ames/SETI Institute/JPL-CalTech
It is a bit bigger and somewhat colder, but a planet circling a star 500 light-years away is otherwise the closest match of our home world discovered so far, astronomers announced on Thursday.
The planet, known as Kepler 186f, named after NASA’s Kepler planet-finding mission, which detected it, has a diameter of 8,700 miles, 10 percent wider than Earth, and its orbit lies within the “Goldilocks zone” of its star, Kepler 186 — not too hot, not too cold, where temperatures could allow for liquid water to flow at the surface, making it potentially hospitable for life.
“Kepler 186f is the first validated, Earth-size planet in the habitable zone of another star,” Elisa V. Quintana of the SETI Institute and NASA’s Ames Research Center in Mountain View, Calif., said at a news conference on Thursday. “It has the right size and is at the right distance to have properties similar to our home planet.”
Dr. Quintana is the lead author of a scientific paper describing the findings in this week’s issue of the journal Science. Kepler 186f is the latest planet to be sifted out of the voluminous data collected by Kepler, which kept watch over 150,000 stars, looking for slight drops in brightness when a planet passed in front.
This follows the announcement last year that another star, Kepler 62, has two planets in its habitable zone, but those two were “super Earths,” with masses probably several times that of Earth. The gravity of those planets might be strong enough to pull in helium and hydrogen gases, making them more like mini-Neptunes than large Earths.
With its smaller size, Kepler 186f is more likely to have an Earth-like rocky surface, another step in astronomers’ quest for what might be called Earth 2.0.
“It’s a progression,” said another member of the discovery team, Thomas S. Barclay of the Bay Area Environmental Research Institute. “This planet really reminds us of Earth.”
The researchers speculate that it is made of the same stuff as Earth — iron, rock, ice, liquid water, although the relative amounts could be very different.
The gravity on Kepler 186f, too, is likely to be roughly the same as Earth’s. “You could far more easily imagine someone being able to go there and walk around on the surface,” Stephen Kane, an astronomer at San Francisco State University and another member of the research team, said in an interview.
Kepler 186f is not a perfect replica, however. It is closer to its star — a red dwarf that is smaller, cooler and fainter than our sun — than the Earth is to its; its year, the time to complete one orbit, is 130 days, not 365. It is also at the outer edge of the habitable zone, receiving less warmth, so perhaps more of its surface would freeze.
“Perhaps it’s more of an Earth cousin than an Earth twin,” Dr. Barclay said.
On the other hand, with its greater mass, Kepler 186f could conceivably have a thicker, insulating atmosphere to compensate. Red dwarfs emit more of their light at the longer infrared wavelengths, which would be more readily absorbed and trapped by ice and gases like water vapor and carbon dioxide.
“This makes the planet more efficient at absorbing energy from its star to avoid freezing over,” said Victoria Meadows, an astrobiologist and planetary astronomer at the University of Washington. “Which is why this planet is still considered potentially habitable, as long as it has a dense enough atmosphere, even though it receives less light from its star than Mars does from our sun.”
She added, “It’s fun to note that if the planet is habitable, photosynthesis may be possible.”
At the wavelengths that plants need, Kepler 186f receives only about a sixth as much light as Earth does, but “there are plenty of Earth plants that would be quite happy with that,” Dr. Meadows said.
Astronomers cannot tell the exact age of the star, but such dwarfs are the longest-lived stars in the universe. If Kepler 186f is habitable, life would have had plenty of time — billions of years — to take hold.
But speculation about the planet will remain speculation for a long time, if not forever. The Kepler measurements indicated only the size of Kepler 186f. It is too far away for astronomers to discern its mass, much less whether it has an atmosphere and oceans or if it teems with living creatures.
Nonetheless, since dwarfs are the most plentiful type of star in the galaxy, astronomers are hopeful that Earth twins are plentiful, and that some will be found close by, allowing other telescopes to make temperature and mass measurements or to identify molecules in the atmosphere.
Kepler’s original mission ended last year, with the failure of equipment that kept the telescope precisely pointed, but scientists still have years of work in analyzing the data, which has so far yielded 962 confirmed planets. More than 2,800 planet candidates remain to be studied.
Correction: April 17, 2014
An earlier version of this article misstated the number of planet candidates found by Kepler that remain to be studied. It is 2,800, not 3,800.

You and Life in Space - What Does it Do To You?

From trouble sleeping to wimpy muscles, living on board the International Space Station really does a number on the human body.
Get to know how your body could react to life in orbit with these 6 fun facts:
You Grow Taller - During the six months that most astronauts spend on the International Space Station, they can grow up to 3 percent taller. Without gravity, the spine is free to expand, making the spaceflyers taller, even when they first return to Earth.
The astronauts return to their preflight height after a few months of being back within the planet's gravity. Expedition 35 Crew Launches to International Space Station
Puffy Faces and Skinny Legs - When on Earth, the fluids in the human body are distributed unevenly because of gravity. Most fluid pools in the lower extremities, leaving little fluid in the top of the body. Life in orbit changes all of that.
For the first few weeks of spaceflight, most astronauts appear to have a puffy head and skinny legs. The fluid in their bodies redistributes evenly when gravity isn't playing a role in their biological systems. After a little time in orbit, however, the body adapts to the new distribution of fluids, and the astronauts don't appear as puffy.
Coordination Conundrum After Landing - After coming home from a stint on the space station, many astronauts have reported difficulty adjusting back to gravity.
Sometimes, space-flyers will drop things, forgetting that gravity is influential back on Earth. After six months in microgravity conditions, it is difficult to adjust to life in a place where materials fall if you drop them.
Muscle Mass Meltdown - In the weightlessness of space, muscles aren't needed to support the body. An astronaut's muscles start to adapt to that change almost immediately. Instead of maintaining the usual base of muscle mass needed for life on Earth, astronauts' bodies quickly get to work ridding themselves of unnecessary tissue.
Although this might be ideal in space, it's problematic once back on Earth. Astronauts have to exercise for two hours a day on the space station just to maintain a healthy amount of muscle mass that they will need once they are back on the planet.
Bone Density Loss - All that exercise on the space station also helps prevent bone-density loss. Each month, astronauts could lose up to 1 percent of their bone density if they don’t get enough exercise.
There are two treadmills and two stationary bicycles on board the space station to help the residents keep in shape during their time in orbit.
You Can't Sleep - Astronauts have reported seeing flashes of light zap through their eyes as they try to rest, making it difficult for them to sleep on the space station.
The flashes are actually from cosmic rays — high-energy particles that beam through the solar system — shooting through the orbiting outpost. Space-flyers have described the flashes as "fireworks" or "streaks." Although the radiation from the cosmic rays can build up over time, the particles don't pose too much of a risk during the limited time that astronauts spend on the station.

Spark Zero-Gravity Fires for Science

Imagine the way a candle burns on Earth. The flame is stretched like a teardrop and it flickers and jumps upwards. Take away gravity and fire looks much different. Flames burn more slowly and in an eerily spherical shape.
On famously nauseating zero-gravity flights out of Houston, Texas, this week, a group of engineering students will light four dozen floating fires to investigate how flames will burn when they are free of Earth's pull.
"We're trying to create some new knowledge," said Sam Avery, an aerospace engineering undergraduate at the University of California, San Diego, who is leading a team of flyers to NASA's Johnson Space Center.
Considering humanity's ancestors have been playing with fire for more than a million years, it's amazing that there's new knowledge to be created. But a weightless environment presents a rare opportunity to study how fire burns when free of gravity's constraints.
"On Earth the convective flow basically speeds up the combustion process and makes it so that you can't get an actual burning rate for your fuel," Avery told Space.com. 

Through convection, hot air expands and rises around a fire as gravity causes colder, denser air to sink below. This process draws fresh oxygen to the fire and pushes out products of combustion (carbon dioxide, light and heat). But without this gravity-driven flow, flames lose their elongated, teardrop shape. They burn at a more sluggish rate, relying on molecular diffusion to feed oxygen to the flame, which actually makes certain characteristics like combustion rate easier to study.
In two separate flights as part of NASA's competitive Microgravity University Program, Avery's team is going to be measuring the burn rate of four different biofuels: butanol, ethanol, E85 and kerosene. (E85 is a fuel made up of 85 percent ethanol and 15 percent gasoline; Avery's supply was donated by a local gas station in California.)
During the flights, a modified Boeing 727 jet will fly up and down in a parabolic path, creating periods of weightlessness up to 30 seconds long. The UCSD team created a contraption that will allow them to light one droplet of fuel during each parabola.
Inside a triple-contained plastic cube, a medical syringe will squirt a blob of one of the fuels onto filaments arranged like crosshairs. When the fuel adheres to the wire cross, what's essentially a barbeque starter will swing around to set the droplet on fire. The fuel will burn for up to 10 seconds in a ball about 3-7 millimeters in diameter, Avery said. He is hoping to complete 12 or 13 trials for each of the four fuels.
Avery led a Microgravity University team through weightless experiments in July 2013, which Space.com's managing editor Tariq Malik got to witness firsthand. In that first round of trials, the students got to test only ethanol. With this next round of flights, the students will be able to compare the burn rate across four different types of fuels, and I'll be following Avery's group of flyers into the plane on Friday (April 11) as the team journalist.
The team members also made some changes to their equipment to make their tests more efficient. In their July trials, the igniter arm pulled back really fast, creating an airflow that increased the burning rate, Avery said. This time, the arm is rigged to move more gently. And the students took some flak for using flammable lithium polymer batteries, Avery said. This time around, they'll use a direct wall outlet plug to power their equipment.
Studying the way different fuels burn in microgravity could have practical implications; a better knowledge of burn rates could help researchers develop more efficient biofuel engines on Earth, as well as more effective fire extinguishers for astronauts on the International Space Station, Avery said.
NASA has used weightless flights to train astronauts since the days of Project Mercury, the United States' first manned space program. The space agency previously used a KC-135 "Weightless Wonder" aircraft, which also earned the nickname the "vomit comet." NASA began buying reduced-gravity flights aboard ZERO-G Corp.'s G-Force One in 2008. (Today thrill-seeking civilians with $5,000 to burn can buy a ticket on a commercial ZERO-G flight, too.)
Students can hitch a ride on a ZERO-G flight if they submit a stellar proposal to the space agency's Microgravity University Program. Avery's team is one of 18 chosen to fly this year out of Ellington Field here near NASA's Johnson Space Center. This week marks the first flight week of 2014 for the program. The full list of 18 teams can be found on NASA's website.

Music and Universe

Music in the soul can be heard by the universe. Lao Tzu
Music is a moral law. It gives soul to the #universe, wings to the mind, flight to the imagination, and charm and gaiety to life and to everything. Plato

Every heart sings a song, incomplete, until another heart whispers back. Those who wish to sing always find a song. At the touch of a lover, everyone becomes a poet. Plato

Universe

I find hope in the darkest of days, and focus in the brightest. I do not judge the universe.
Dalai Lama
 
As you simplify your life, the laws of the universe will be simpler; solitude will not be solitude, poverty will not be poverty, nor weakness weakness. Henry David Thoreau

That deep emotional conviction of the presence of a superior reasoning power, which is revealed in the incomprehensible universe, forms my idea of God. Albert Einstein

NASA Breaks Most Contact With Russia

NASA said Wednesday that it was suspending most contacts with Russian space agency officials, underscoring just how rapidly the Russian-American relationship is deteriorating in the wake of the Kremlin’s annexation of Crimea and hinting at further ramifications that will go beyond previous rifts.

The one exception, NASA said, would involve operations of the International Space Station, the primary space collaboration between the two countries.

Otherwise, the extent of NASA’s break in relations is broad and includes “travel to Russia and visits by Russian government representatives to NASA facilities, bilateral meetings, email, and teleconferences or video conferences,” Michael F. O’Brien, the agency’s associate administrator for international and inter-agency relations, wrote in an email to top NASA officials.

Over the years of collaboration, the Russian-American partnership in space has continued largely immune to the geopolitical ups and downs between Washington and Moscow, and as recently as a few weeks ago officials expressed optimism that would still be the case, with the NASA administrator, Charles F. Bolden Jr., saying, “Right now, everything is normal in our relationship with the Russians.”

But as the confrontation over Ukraine intensifies, it became untenable for the Obama administration to continue sending NASA officials to Russia or hosting their space agency officials in the United States as if all were normal, even as Washington cut off trade talks and military cooperation and threw Russia out of the Group of 8 industrial nations.

Defense Secretary Chuck Hagel has also directed the Air Force to review the use of Russian engines in rockets that send American military satellites into orbit. The Atlas 5 rockets, now produced by a joint venture of Boeing and Lockheed Martin, have been built for years with Russian-made RD-180 engines. American officials are exploring the consequences of possible supply interruptions.

Still, the administration was not going so far as to cut off all cooperation, especially just a week after sending a NASA astronaut to the International Space Station along with two Russian cosmonauts in a Russian capsule. Further measures could seriously jeopardize the American space program.

 As Moscow’s grip on Crimea tightens, ethnic Russians who were born under Soviet rule are eager to recapture their identity.

Since the retirement of the space shuttles, NASA astronauts get their rides into orbit aboard Russian Soyuz rockets at a cost of up to $70 million a seat. NASA is financing commercial companies to develop rockets and spacecraft to start carrying astronauts as soon as 2017. At a congressional hearing last week, Mr. Bolden said the program, called commercial crew, was the “critical need” for the human spaceflight program.

The new restrictions are similar to ones that limit what NASA is allowed to do with China because of worries, particularly by Representative Frank R. Wolf, Republican of Virginia, that China would take advantage of collaborations to copy American technologies. Under those rules, NASA cannot host any Chinese citizens.

The decision to suspend the relationship with the Russian space agency is unusual for several reasons, not least because keeping the space enterprises alive has long been a symbol of Washington’s commitment to an apolitical working relationship with Moscow. Breaking it, some government officials have feared, would invite the Russians to retaliate by suspending nuclear inspections under the new Start treaty - inspections that have continued despite the differences over Ukraine.

But the Obama administration’s decision was made easier by the dwindling nature of the nation’s space program. Grand plans for international space programs have largely withered, as the space shuttle program has ground to an end. “There’s a sense that we don’t need the space relationships the way we once did,” one senior government scientist said, “because we don’t have as much going on in space.”

A version of this article appears in print on April 3, 2014, on page A12 of the New York edition with the headline: NASA Breaks Most Contact With Russia.

A Moon of Saturn has a Sea, Scientists Say

A view of Saturn's fourth-largest moon, Enceladus, as seen from the Cassini spacecraft. Credit NASA

Inside a moon of Saturn, beneath its icy veneer and above its rocky core, is a sea of water the size of Lake Superior, scientists announced on Thursday.

The findings, published in the journal Science, confirm what planetary scientists have suspected about the moon, #Enceladus, ever since they were astonished in 2005 by photographs showing geysers of ice crystals shooting out of its south pole.

“What we’ve done is put forth a strong case for an ocean,” said David J. Stevenson, a professor of planetary science at the California Institute of Technology and an author of the Science paper.

For many researchers, this tiny, shiny cue-ball of a moon, just over 300 miles wide, is now the most promising place to look for life elsewhere in the solar system, even more than Mars.

“Definitely Enceladus,” said Larry W. Esposito, a professor of astrophysical and planetary sciences at the University of Colorado, who was not involved in the research. “Because there’s warm water right there now.”

Enceladus (pronounced en-SELL-a-dus) is caught in a gravitational tug of war between Saturn and another moon, Dione, which bends its icy outer layer, creating friction and heat. In the years since discovering the geysers, NASA’s Cassini spacecraft has made repeated flybys of Enceladus, photographing the fissures (nicknamed tiger stripes) where the geysers originate, measuring temperatures and identifying carbon-based organic molecules that could serve as building blocks for life.

Cassini has no instruments that can directly detect water beneath the surface, but three flybys in the years 2010-12 were devoted to producing a map of the gravity field, noting where the pull was stronger or weaker. During the flybys, lasting just a few minutes, radio telescopes that are part of NASA’s Deep #Space Network broadcast a signal to the spacecraft, which echoed it back to Earth. As the pull of Enceladus’ gravity sped and then slowed the spacecraft, the frequency of the radio signal shifted, just as the pitch of a train whistle rises and falls as it passes by a listener.

Using atomic clocks on Earth, the scientists measured the radio frequency with enough precision that they could discern changes in the velocity of Cassini, hundreds of millions of miles away, as minuscule as 14 inches an hour.

They found that the moon’s gravity was weaker at the south pole. At first glance, that is not so surprising; there is a depression at the pole, and lower mass means less gravity. But the depression is so large that the gravity should actually have been weaker.

“Then you say, ‘Aha, there must be compensation,'” Dr. Stevenson said. “Something more dense under the ice. The natural candidate is water.”

Liquid water is 8 percent denser than ice, so the presence of a sea 20 to 25 miles below the surface fits the gravity measurements. “It’s an ocean that extends in all directions from the south pole to about halfway to the equator,” Dr. Stevenson said.

The underground sea is up to six miles thick, much deeper than a lake. “It’s a lot more water than Lake Superior,” Dr. Stevenson said. “It may even be bigger. The ocean could extend all the way to the north pole.”

The conclusion was not a surprise, said Christopher P. McKay, a planetary scientist at NASA Ames Research Center in Mountain View, Calif., who studies the possibility of life on other worlds, but “it confirms in a really robust way what has been sort of been the standard model.”

 It also makes Enceladus a more attractive destination for a future mission, especially one that would collect samples from the plumes and return them to Earth to see if they contain any microbes.

The discussion on the possibility of extraterrestrial life in the solar system centers on four bodies: Mars, Enceladus, Jupiter’s moon Europa, and Titan, another moon of Saturn.

Dr. McKay, who was not involved with gravity measurements, noted that only Enceladus was known to possess the four essential ingredients for life, at least as it exists on Earth: liquid water, energy, carbon and nitrogen.

“I would say it’s our best bet,” he said.

Mars has a dearth of nitrogen, found in amino acids and proteins, and the surface today is dry and cold. Europa, which also possesses an under-ice ocean, may have all of the ingredients, but that has not been confirmed. Ice plumes have also been observed coming off Europa’s south pole, but intermittently. Titan is the most intriguing and speculative possibility, with lakes of liquid methane, not water. If life existed there, it would be far different from that on Earth.

Still, life on Enceladus is perhaps a long shot. The sea is at freezing temperature and in continual darkness. And the water may have been liquid only in the recent past, a few tens of millions of years, a blink in the 4.5-billion-year history of the solar system. But scientists also do not know how long it takes life to get started, and some think it could happen quickly.

“Is there life in the plume?” Dr. McKay said. “To answer that question, a sample return would be the way.”

There are a couple of proposals for that already, including one by Peter Tsou, a retired scientist from NASA’s Jet Propulsion Laboratory. Dr. Tsou devised a way to capture comet particles and bring them back to Earth for NASA’s Stardust mission and has been suggesting a similar method for a spacecraft that would fly through Enceladus’ plumes and then return to Earth for scientists to examine.

The challenges are to make sure that the interesting particles would not break apart, to take precautions that any alien life would not infect Earth, and to fit it into the $500 million budget of one of NASA’s lower-cost planetary missions.

NASA Space Assets Detect Ocean Inside Saturn Moon

Gravity measurements by NASA's Cassini spacecraft and Deep Space Network suggest that Saturn's moon Enceladus, which has jets of water vapor and ice gushing from its south pole, also harbors a large interior ocean beneath an ice shell, as this illustration depicts. Image credit: NASA/JPL-Caltech

April 03, 2014

NASA's Cassini spacecraft and Deep Space Network have uncovered evidence #Saturn's moon Enceladus harbors a large underground ocean of liquid water, furthering scientific interest in the moon as a potential home to extraterrestrial microbes.

Researchers theorized the presence of an interior reservoir of water in 2005 when Cassini discovered water vapor and ice spewing from vents near the moon's south pole. The new data provide the first geophysical measurements of the internal structure of Enceladus, consistent with the existence of a hidden ocean inside the moon. Findings from the gravity measurements are in the Friday, April 4 edition of the journal Science.

"The way we deduce gravity variations is a concept in physics called the Doppler Effect, the same principle used with a speed-measuring radar gun," said Sami Asmar of NASA's Jet Propulsion Laboratory in Pasadena, Calif., a coauthor of the paper. "As the spacecraft flies by Enceladus, its velocity is perturbed by an amount that depends on variations in the gravity field that we're trying to measure. We see the change in velocity as a change in radio frequency, received at our ground stations here all the way across the solar system."

The gravity measurements suggest a large, possibly regional, ocean about 6 miles (10 kilometers) deep, beneath an ice shell about 19 to 25 miles (30 to 40 kilometers) thick. The subsurface ocean evidence supports the inclusion of Enceladus among the most likely places in our solar system to host microbial life. Before Cassini reached Saturn in July 2004, no version of that short list included this icy moon, barely 300 miles (500 kilometers) in diameter.

"This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole," said David Stevenson of the California Institute of Technology, Pasadena, one of the paper's co-authors.

Cassini has flown near Enceladus 19 times. Three flybys, from 2010 to 2012, yielded precise trajectory measurements. The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft's flight path. Variations in the gravity field, such as those caused by mountains on the surface or differences in underground composition, can be detected as changes in the spacecraft's velocity, measured from Earth.

The technique of analyzing a radio signal between Cassini and the Deep Space Network can detect changes in velocity as small as less than one foot per hour (90 microns per second). With this precision, the flyby data yielded evidence of a zone inside the southern end of the moon with higher density than other portions of the interior.

The south pole area has a surface depression that causes a dip in the local tug of gravity. However, the magnitude of the dip is less than expected given the size of the depression, leading researchers to conclude the depression's effect is partially offset by a high-density feature in the region, beneath the surface.

"The Cassini gravity measurements show a negative gravity anomaly at the south pole that however is not as large as expected from the deep depression detected by the onboard camera," said the paper's lead author, Luciano Iess of Sapienza University of Rome. "Hence the conclusion that there must be a denser material at depth that compensates the missing mass: very likely liquid water, which is seven percent denser than ice. The magnitude of the anomaly gave us the size of the water reservoir."

There is no certainty the subsurface ocean supplies the water plume spraying out of surface fractures near the south pole of Enceladus, however, scientists reason it is a real possibility. The fractures may lead down to a part of the moon that is tidally heated by the moon's repeated flexing, as it follows an eccentric orbit around Saturn.

Much of the excitement about the Cassini mission's discovery of the Enceladus water plume stems from the possibility that it originates from a wet environment that could be a favorable environment for microbial life.

"Material from Enceladus' south polar jets contains salty water and organic molecules, the basic chemical ingredients for life," said Linda Spilker, Cassini's project scientist at JPL. "Their discovery expanded our view of the 'habitable zone' within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate in Washington. For more information about Cassini, visit:

http://www.nasa.gov/cassini  and http://saturn.jpl.nasa.gov

Color Explosion

click on image above to view in lightbox

"The Earth is a very small stage in a vast cosmic arena." But to us, it's everything. The place where we live, love, work and play. The place where we are born and where we die. From space, Earth is big, blue and beautiful; fragile and inspiring. It's the only planet we've ever been to, and the only home we've ever known. 

This image, captured by the Landsat-8 satellite, shows the view over Western Australia on May 12, 2013. The image shows rich sediment and nutrient patterns in a tropical estuary area and complex patterns and conditions in vegetated areas. 

The image is enhanced and involved masking, separately enhancing and then reassembling water and land portions of the image. The water patterns are the result of an RGB display of Landsat-8’s red, blue, and ultra-blue bands. Land is shown using short-wavelength-infrared, near-infrared and green. 

Download image: 1920 x 1200  |  1600 x 1200

NASA/USGS Landsat; Geoscience Australia. Source: Landsat gallery.

The King of Planets

As springtime winds begin to blow, a giant celestial kite sets sail, riding high in the night sky. For sky-watchers, another delightful week is ahead for observing the heavens, with the moon waxing after an early absence and taking a starring role in the celestial encounters ahead.

Springtime kite. With the moon missing for most of the night on Monday, March 31, sky-watchers can track down the distinctive constellation Bootes, the Herdsman, and its red giant star.

A good stargazing trick that will aid observers in finding this bright constellation is to start off at the Big Dipper, now high in the northeastern sky in the late evenings. Appearing to hang upside down, the handle of the Big Dipper offers up three stars that point in an imaginary line down toward the horizon. Follow the line until you hit the next brightest star. Voila, you have found Arcturus, the brightest star of Bootes (see sky map below).

While the remaining five stars that make up the kite shape are quite faint to the naked eye, Arcturus will knock your eyes out.

This sky chart shows the early evening sky looking toward the northeast, where the Big Dipper handle points directly toward Arcturus, the lead star in the constellation Bootes.

That’s because Arcturus is one of the closest stars to us at 37.5 light-years away. It is also considered the fourth brightest star in the entire night sky, and is a real giant at some 20 million miles (32,186,880 kilometers) wide—25 times wider than our sun. If our puny sun were replaced by this behemoth, the outer edge of the star would reach as far as the orbit of Mars, and Earth would be swallowed up by its atmosphere.

Moon and the Bull. After nightfall on Wednesday, April 2, look for the thin crescent moon hanging below the gems of the constellation Taurus, the Bull, low in the western sky.

Nearly straight above the moon is the jewel-like star cluster known as the Pleiades or Seven Sisters. To the naked eye, the 400 light-year-distant, deep-sky treasure trove resembles a fuzzy group of stars. But binoculars and small telescopes bring into the Pleiades stunning focus.

Meanwhile, to the upper left of the moon will be the orange-hued, dying stellar giant Aldebaran, and the distinctively V-shaped Hyades star cluster.

Hyades eclipse. By the next evening, Thursday, April 3, the waxing crescent moon will slide in front of the Hyades cluster. The moon will appear to sit just to the lower right of 65 light-year-distant Aldebaran, which marks the left top of the V-shaped Hyades. Aldebaran may look like part of the cluster, but in reality it is about half as far away as the cluster members are. On Monday, lucky sky-watchers in much of North America will glimpse (through their backyard telescopes) up to three of the Hyades’ fainter members as they are eclipsed, or occulted, by the moon when its unlit portion passes in front of them.

Moon and Jupiter. For those who love planet-watching, Jupiter is easy to find on Saturday, April 6, thanks to the silvery moon pointing the way in the southwestern evening sky. The pair together will make for a spectacular sky sight, even with unaided eyes from brightly lit urban locations.

This sky chart shows Jupiter and the moon together in the constellation Gemini on the evening of April 6.

A near quarter-moon pays a visit to Jupiter, passing only 5 degrees south of the king of planets. Don’t forget to point your binoculars at Jupiter and watch its four largest moons beside it. Even the smallest of telescopes will reveal dark cloud belts and the Great Red Spot, a Jovian hurricane three times the size of Earth.

Giant Balloon Trips to Near-Space

By the end of 2016, private company World View hopes to take tourists to near-space — not with a rocket, but with a high-altitude balloon.