What is Low Earth Orbit?

Beginning in the 1950s with the Sputnik, Vostok and Mercury programs, human beings began to “slip the surly bonds of Earth”. And for a time, all of our missions were what is known as Low-Earth Orbit (LEO). Over time, with the Apollo missions and deep space missions involving robotic spacecraft (like the Voyager missions), we began to venture beyond, reaching the Moon and other planets of the Solar System.

But by and large, the vast majority of missions to space over the years – be they crewed or uncrewed – have been to Low-Earth Orbit. It is here that the Earth’s vast array of communications, navigation and military satellites reside. And it is here that the International Space Station (ISS) conducts its operations, which is also where the majority of crewed missions today go. So just what is LEO and why are we so intent on sending things there? Continue reading “What is Low Earth Orbit?”

How Low Can You Orbit?

The Earth’s atmosphere is a total drag, especially if you’re trying to orbit our planet. So how low can you go?

The Earth’s atmosphere is a total drag, especially if you’re trying to orbit our planet. It’s a drag. Get it? Atmospheric drag. Drag. Drag.

Hi, my name is Fraser Cain. I’m the publisher of Universe Today, and sometimes my team lets me write my own jokes.

I could have started off this episode with a reference to the “Adama Drop” in-atmosphere viper deployment from BSG, but instead I went with a Dad joke. My punishment is drawing attention to it.

So how low can you go? And if you go low enough, will Ludacris appear in the mirror?

We all appreciate the Earth’s atmosphere and everything it does for you. With all the breathing, and the staying warm and the not having horrible bruises all over your body from teeny space rocks pummeling us.

I’ve got an alternative view. The Earth’s atmosphere is your gilded pressurized oxygenated cage, and it’s the one thing keeping you from flying in space.And as we all know, this is your destiny.

Without the atmosphere, you could easily orbit the Earth, a few kilometers over its surface. Traveling around and around the planet like a person sized Moon. Wouldn’t that be great?

Well, it’s not going to happen. As you walk through the atmosphere, you bonk into all the air molecules. You don’t feel it when you’re moving at walking speed, but go faster, like an airplane, and it’ll rock you like a hurricane.

Without constant thrust pushing against the atmosphere, you’ll keep slowing down, and when you’re trying to orbit the planet, it’s a killer. Our atmosphere is like someone is constantly pushing the brakes on the fly in space party.

Credit

If you’ve played Kerbal Space Program, you know the faster you’re traveling, the higher you orbit. Conversely, the slower you travel, the lower you orbit. Travel slow enough and you’ll eat it, and by it, I meant as much planet as you can co-exist with after a high speed impact.

Being more massive means more momentum to push against the atmospheric drag. But with a large surface area, it acts like a parachute, slowing you down.

Hey, I know something that’s super massive with a huge surface area. The International Space Station orbits the planet at an altitude between 330 km and 435 km.

Why such a big range? The atmosphere is constantly pushing against the ISS as it orbits the planet. This slows down the space station’s speed and lowers its orbit. It wouldn’t last more than a couple of years if it wasn’t able to counteract the atmospheric drag.

The International Space Station, photographed by the crew of STS-132 as they disembarked. Credit: NASA
The International Space Station, photographed by the crew of STS-132 as they disembarked. Credit: NASA

Fortunately, the station has rockets to increase its speed, and a faster speed means a higher orbit. It can even get assistance from docked spacecraft. If the space station were to go any lower, it would require higher and higher amounts of thrust to prevent re-entry into the Earth’s atmosphere.

So what are the limits? Anything below 160 km altitude will essentially re-enter almost immediately, as it’s buffeted by the thicker atmosphere. You really wouldn’t last more than a few hours at that altitude, but above 800 km you could orbit for more than 100 years.

Geosynchronous satellites that orbit the Earth and transmit our television signals are at an altitude of about 42,000 km. Satellites that high are never coming back down. Well, maybe not never.

Want to enjoy your orbital experience? Make sure you get yourself to an altitude of at least 300 km, 400 km just to be safe. You should shoot for more like 800 km if you just don’t want to worry about things for a while.

Knowing these risks, would you be willing to travel to orbit with current technology? Tell us in the comments below.

Bigelow Inflatable Module to be Added to Space Station in 2015

Astronauts aboard the International Space Station are going to be getting an addition in the near future, and in the form of an inflatable room no less. The Bigelow Expandable Activity Module (BEAM) is the first privately-built space habitat that will added to the ISS, and it will be transported into orbit aboard a Space X Falcon 9 rocket sometime next year.

“The BEAM is one small step for Bigelow Aerospace,” Bigelow representative Michael Gold told Universe Today, “but is also one giant leap for private sector space activities since the BEAM will be the first privately owned and developed module ever to be part of a crewed system in space.”

Continue reading “Bigelow Inflatable Module to be Added to Space Station in 2015”

Tour Around Boeing’s CST-100 Spaceliner to LEO: Photos

KENNEDY SPACE CENTER, FL – On Monday, June 9, Boeing revealed the design of their CST-100 astronaut spaceliner aimed at restoring Americas ability to launch our astronauts to low-Earth orbit (LEO) and the International Space Station (ISS) by 2017.

The full scale CST-100 mockup was unveiled at an invitation only ceremony for Boeing executives and media held inside a newly renovated shuttle era facility at the Kennedy Space Center where the capsule would start being manufactured later this year.

Universe Today was invited to tour the capsule for a first hand inspection of the CST-100’s interior and exterior and presents my photo gallery here.

Hatch opening to Boeing’s commercial CST-100 crew transporter.  Credit: Ken Kremer - kenkremer.com
Hatch opening to Boeing’s commercial CST-100 crew transporter. Credit: Ken Kremer – kenkremer.com

The CST-100 is a privately built manrated capsule being developed with funding from NASA under the auspices of the agency’s Commercial Crew Program (CCP) in a public/private partnership between NASA and private industry.

The vehicle will be assembled inside the refurbished processing hangar known during the shuttle era as Orbiter Processing Facility-3 (OPF-3). Boeing is leasing the site from Space Florida.

Boeing is one of three American aerospace firms vying for a NASA contract to build an American ‘space taxi’ to ferry US astronauts to the space station and back as soon as 2017.

Boeing CST-100 capsule interior up close.  Credit: Ken Kremer - kenkremer.com
Boeing CST-100 capsule interior up close. Credit: Ken Kremer – kenkremer.com

The SpaceX Dragon and Sierra Nevada Dream Chaser are also receiving funds from NASA’s commercial crew program.

NASA will award one or more contracts to build Americas next human rated spaceship in August or September.

Boeing CST-100 crew capsule will carry five person crews to the ISS.  Credit: Ken Kremer - kenkremer.com
Boeing CST-100 crew capsule will carry five person crews to the ISS. Credit: Ken Kremer – kenkremer.com

Since the forced shutdown of NASA’s Space Shuttle program following its final flight in 2011, US astronauts have been 100% dependent on the Russians and their cramped but effective Soyuz capsule for rides to the station and back – at a cost exceeding $70 million per seat.

Boeing unveiled full scale mockup of their commercial  CST-100  'Space Taxi' on June 9, 2014 at the Kennedy Space Center in Florida.  The private vehicle will launch US astronauts to low Earth orbit and the ISS from US soil.   Credit: Ken Kremer - kenkremer.com
Boeing unveiled full scale mockup of their commercial CST-100 ‘Space Taxi’ on June 9, 2014 at the Kennedy Space Center in Florida. The private vehicle will launch US astronauts to low Earth orbit and the ISS from US soil. Credit: Ken Kremer – kenkremer.com

Chris Ferguson, the final shuttle commander for NASA’s last shuttle flight (STS-135) now serves as director of Boeing’s Crew and Mission Operations.

Ferguson and the Boeing team are determined to get Americans back into space from American soil with American rockets.

Read my exclusive, in depth one-on-one interviews with Chris Ferguson – America’s last shuttle commander – about the CST-100; here and here.

Boeing unveiled full scale mockup of their commercial  CST-100  'Space Taxi' on June 9, 2014 at its intended manufacturing facility at the Kennedy Space Center in Florida.  The private vehicle will launch US astronauts to low Earth orbit and the ISS from US soil.   Credit: Ken Kremer - kenkremer.com
Boeing unveiled full scale mockup of their commercial CST-100 ‘Space Taxi’ on June 9, 2014 at its intended manufacturing facility at the Kennedy Space Center in Florida. The private vehicle will launch US astronauts to low Earth orbit and the ISS from US soil. Credit: Ken Kremer – kenkremer.com

The vehicle includes five recliner seats, a hatch and windows, the pilots control console with several attached Samsung tablets for crew interfaces with wireless internet, a docking port to the ISS and ample space for 220 kilograms of cargo storage of an array of equipment, gear and science experiments depending on NASA’s allotment choices.

The interior features Boeing’s LED Sky Lighting with an adjustable blue hue based on its 787 Dreamliner airplanes to enhance the ambience for the crew.

Astronaut mannequin seated below pilot console inside Boeing’s commercial CST-100 'Space Taxi' mockup.  Credit: Ken Kremer - kenkremer.com
Astronaut mannequin seated below pilot console inside Boeing’s commercial CST-100 ‘Space Taxi’ mockup. Credit: Ken Kremer – kenkremer.com
Five person crews will fly Boeing CST-100 capsule to ISS. Credit: Ken Kremer - kenkremer.com
Five person crews will fly Boeing CST-100 capsule to ISS. Credit: Ken Kremer – kenkremer.com

The reusable capsule will launch atop a man rated United Launch Alliance (ULA) Atlas V rocket.

Stay tuned here for Ken’s continuing Boeing, SpaceX, Orbital Sciences, commercial space, Orion, Curiosity, Mars rover, MAVEN, MOM and more planetary and human spaceflight news.

Ken Kremer

US astronauts will eventually enter the ISS through this docking port. Credit: Ken Kremer - kenkremer.com
US astronauts will eventually enter the ISS through this docking port. Credit: Ken Kremer – kenkremer.com
US Senator Bill Nelson (FL) and NASA’s final space shuttle commander inside Boeing’s CST-100 manned capsule during unveiling ceremony at the Kennedy Space Center, Florida on June 9, 2014.  Nelson is seated below pilots console and receives CST-100 briefing from Ferguson who now directs Boeing’s crew efforts.  Nelson also flew in space aboard the Columbia shuttle in Jan. 1986.  Credit: Ken Kremer - kenkremer.com
US Senator Bill Nelson (FL) and NASA’s final space shuttle commander inside Boeing’s CST-100 manned capsule during unveiling ceremony at the Kennedy Space Center, Florida on June 9, 2014. Nelson is seated below pilots console and receives CST-100 briefing from Ferguson who now directs Boeing’s crew efforts. Nelson also flew in space aboard the Columbia shuttle in Jan. 1986. Credit: Ken Kremer – kenkremer.com
Boeing CST-100 spaceship unveiled at Kennedy Space Center FL on June 9, 2014 Posing from left to right; Frank DelBello, Space Florida, John Elbon, Boeing VP Space Exploration, US Sen. Bill Nelson (FL), final shuttle commander Chris Ferguson, Boeing Director of Crew and Mission Operations and John Mulholland, Boeing VP Commercial Space Exploration.  Credit: Ken Kremer - kenkremer.com
Boeing CST-100 spaceship unveiled at Kennedy Space Center FL on June 9, 2014 Posing from left to right; Frank DelBello, Space Florida, John Elbon, Boeing VP Space Exploration, US Sen. Bill Nelson (FL), final shuttle commander Chris Ferguson, Boeing Director of Crew and Mission Operations and John Mulholland, Boeing VP Commercial Space Exploration. Credit: Ken Kremer – kenkremer.com

US Senator Bill Nelson (FL) addresses crowd at unveiling ceremony for Boeing’s CST-100 manned capsule to the ISS at the Kennedy Space Center, Florida on June 9, 2014.  Credit: Ken Kremer - kenkremer.com
US Senator Bill Nelson (FL) addresses crowd at unveiling ceremony for Boeing’s CST-100 manned capsule to the ISS at the Kennedy Space Center, Florida on June 9, 2014. Credit: Ken Kremer – kenkremer.com

Boeing's CST-100 project engineer Tony Castilleja describes the capsule during a fascinating interview with Ken Kremer/Universe Today on June 9, 2014 while sitting inside the full scale mockup of the Boeing CST-100 space taxi during unveiling ceremony at NASA's Kennedy Space Center. Credit: Ken Kremer - kenkremer.com
Boeing’s CST-100 project engineer Tony Castilleja describes the capsule during a fascinating interview with Ken Kremer/Universe Today on June 9, 2014 while sitting inside the full scale mockup of the Boeing CST-100 space taxi during unveiling ceremony at NASA’s Kennedy Space Center. Credit: Ken Kremer – kenkremer.com

How to See 209P/LINEAR, the Comet Brewing Up Saturday’s Surprise Meteor Shower

As we anxiously await the arrival of a potentially rich new meteor shower this weekend, its parent comet, 209P/LINEAR, draws ever closer and brighter. Today it shines feebly at around magnitude +13.7 yet possesses a classic form with bright head and tail. It’s rapidly approaching Earth, picking up speed every night and hopefully will be bright enough to see in your telescope very soon. 

As it approaches Earth in the coming nights, comet 209P/LINEAR will appear to move quickly across the sky, traveling from Leo Minor to southern Hydra in little over a week. All maps created with Chris Marriott's SkyMap software
As it approaches Earth in the coming nights, comet 209P/LINEAR will move quickly across the sky, traveling from Ursa Major to southern Hydra in just 10 days. When closest on May 28-29, the comet will cover 10 degrees per day or just shy of 1/2 degree per hour. All maps created with Chris Marriott’s SkyMap software

The comet was discovered in Feb. 2004 by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) automated sky survey. Given its stellar appearance at the time of discovery it was first thought to be an asteroid, but photos taken the following month photos by Rob McNaught (Siding Spring Observatory, Australia) revealed a narrow tail. Unlike long period comets Hale-Bopp and the late Comet ISON that swing around the sun once every few thousand years or few million years, this one’s a frequent visitor, dropping by every 5.09 years.

This detailed map shows the comet's path from Leo Minor across the backside of the Sickle of Leo May 23-26. Hopefully it will be bright enough then to spot in an 8-inch or larger telescope. Click to enlarge and then print out for use at the telescope.
This detailed map shows the comet’s path from Leo Minor across the backside of the Sickle of Leo May 23-26. Hopefully it will be bright enough then to spot in an 8-inch or larger telescope. On May 25, it passes close to the colorful double star Gamma Leonis and a pair of NGC galaxies. Stars plotted to magnitude +9. Click to enlarge and then print out for use at the telescope.

209P/LINEAR belongs to the Jupiter family of comets, a group of comets with periods of less than 20 years whose orbits are controlled by Jupiter. When closest at perihelion, 209P/LINEAR coasts some 90 million miles from the sun; the far end of its orbit crosses that of Jupiter. Comets that ply the gravitational domain of the solar system’s largest planet occasionally get their orbits realigned. In 2012, during a relatively close pass of that planet, Jupiter perturbed 209P’s orbit, bringing the comet and its debris trails to within 280,000 miles (450,000 km) of Earth’s orbit, close enough to spark the meteor shower predicted for this Friday night/Saturday morning May 23-24.

Track of the comet through from May 27-29 through the dim constellation Sextans south of Leo.
Track of the comet from May 27-29 through Sextans to the Hydra-Crater border with positions shown every 3 hours. Times are CDT. Click to enlarge.

This time around the sun, the comet itself will fly just 5.15 million miles (21 times the distance to the moon) from Earth around 3 a.m. CDT (8 hours UT) May 29 a little more than 3 weeks after perihelion, making it the 9th closest comet encounter ever observed. Given , you’d think 209P would become a bright object, perhaps even visible with the naked eye, but predictions call for it to reach about magnitude +11 at best. That means you’ll need an 8-inch telescope and dark sky to see it well. Either the comet’s very small or producing dust at a declining rate or both. Research published by Quanzhi Ye and Paul A. Wiegert describes the comet’s current dust production as low, a sign that 209P could be transitioning to a dormant comet or asteroid.

Light curve for comet 209P/LINEAR predicts a maximum magnitude of around 11. Click for more information. Credit: Seiichi Yoshida
Light curve for comet 209P/LINEAR forecasts a maximum magnitude of around 11. Dates are shown along the bottom and magnitude scale along the side. Click for additional information. Credit: Seiichi Yoshida

Fortunately, the moon’s out of the way this week and next when 209P/LINEAR is closest and brightest. Since we enjoy comets in part because of their unpredictability, maybe a few surprises will be in the offing including a brighter than expected appearance. The maps will help you track down 209P during the best part of its apparition. I deliberately chose ‘black stars on a white background’ for clarity in use at the telescope. It also saves on printer ink!

A brand new meteor shower shooting 100 and potentially as many as 400 meteors an hour may radiate from the dim constellation Camelopardalis below the North Star Saturday morning May 24. This map shows the sky facing north around 2 a.m. from the central U.S. around 2 a.m. Saturday.  Stellarium
A brand new meteor shower shooting 100 and potentially as many as 400 meteors an hour may radiate from the dim constellation Camelopardalis below the North Star Saturday morning May 24. Each is crumb or pebble of debris lost by 209P/LINEAR during earlier cycles around the sun. This map shows the sky facing north around 2 a.m. from the Saturday May 24 from the central U.S. Stellarium

We’re grateful for the dust 209P/LINEAR carelessly lost during its many passes in the 19th and early 20th centuries. Earth is expected to pass through multiple filaments of debris overnight Friday May 23-24 with the peak of at least 100 meteors per hour – about as good as a typical Perseid or Geminid shower – occurring around 2 a.m. CDT (7 hours UT).

If it’s cloudy or you’re not in the sweet zone for viewing either the comet or the potential shower, astrophysicist Gianluca Masi will offer a live feed of the comet at the Virtual Telescope Project website scheduled to begin at 3 p.m. CDT (8 p.m. Greenwich Time) May 22. A second meteor shower live feed will start at 12:30 a.m. CDT (5:30 a.m. Greenwich Time) Friday night/Saturday morning May 23-24.

SLOOH will also cover 209P/LINEAR live on the Web with telescopes on the Canary Islands starting at 5 p.m. CDT (6 p.m. EDT, 4 p.m. MDT and 3 p.m. PDT) May 23.  Live meteor shower coverage featuring astronomer Bob Berman of Astronomy Magazine begins at 10 p.m. CDT. Viewers can ask questions by using hashtag #slooh.

A very exciting weekend lies ahead!

Exploded Rocket Fragments Could Endanger ISS and Future Missions

The International Space Station will have to look out for new debris from an exploded Russian rocket (NASA image)

Traveling through low-Earth orbit just got a little more dangerous; a drifting Russian Breeze M (Briz-M) rocket stage that failed to execute its final burns back on August 6 has recently exploded, sending hundreds of shattered fragments out into orbit.

Russia and the U.S. Defense Department (JFCC-Space) have stated that they are currently tracking 500 pieces of debris from the disintegrated Breeze M, although some sources are saying there are likely much more than that.

After a successful liftoff via Proton rocket on August 6 from the Baikonur Cosmodrome, the Breeze M upper stage’s engines shut off after only 7 seconds as opposed to the normal 18 minutes, leaving its fuel tanks filled with 10 to 15 tons of hydrazine and nitrogen tetroxide propellants. Its payloads, the Indonesian Telkom 3 and the Russian Express-MD2 communications satellites, were subsequently deployed into the wrong orbits as the Breeze M computer continued functioning.

Although originally expected to remain intact for at least another year, the rocket stage “violently disintegrated” on October 16. Evidence of the explosion was first observed by astronomer Robert McNaught at Australia’s Siding Springs Observatory, who counted 70 fragments visible within the narrow field-of-view telescope he was using for near-Earth asteroid observations.

The exact cause of the explosion isn’t known — it may have been sparked by an impact with another piece of space junk or the result of stresses caused by the Breeze M’s eccentric orbit, which varied in altitude from 265 to 5,015 kilometers (165 miles to 3,118 miles) with an inclination of 49.9 degrees.

This was the third such breakup of a partially-full Breeze M upper stage in orbit, the previous events having occurred in 2007 and 2010, and yet another Breeze M still remains in orbit after a failed burn in August 2011.

Most of the latest fragments are still in orbit at altitudes ranging from 250 to 5,000 km (155 to 3,100 miles), where they are expected to remain.

“Although some of the pieces have begun to re-enter, most of the debris will remain in orbit for an extended period of time.”

– Jamie Mannina, US State Department spokesperson

According to NASA the debris currently poses no immediate threat to the Space Station although the cloud is “believed not to be insignificant.” Still, according to a post on Zarya.com the Station’s course will periodically take it within the Breeze M debris cloud, and “will sometimes spend several days at a time with a large part of its orbit within the cloud.”

Source: RT.com and SpaceflightNow.com.  Inset image: the Breeze M (Briz-M) upper stage which disintegrated on Oct. 16. (Khrunichev)

Weekly SkyWatcher’s Forecast: April 9-15, 2012

[/caption]Greetings, fellow SkyWatchers! It’s shaping up to be a great week to enjoy astronomy. For both hemispheres, the Virginid Meteor shower is underway and its peak occurs late Monday night / early Tuesday morning. Need more celestial fireworks? Then keep looking up as the “April Fireballs” will be visiting, with their peak beginning about a week from today and lasting for 24 days. Even if you only catch one of these bright travelers as they sparkle across the starry sky, it will make your night! But hang on, there will be plenty to explore. Bright stars and bright planets are featured – as well as some of the season’s best galaxies. Keep your telescope out and don’t get spooked, because the “Ghost of Jupiter” will be a challenge object! If you want to know more about astonomy history, and what you can see with just your eyes and your optics, then meet me in the back yard…

Monday, April 9 – Tonight let’s take a journey towards the 25th brightest star in the night sky – 1.3 magnitude, Alpha Leonis. Regulus, known as “The Little King,” is the brightest star in Leo. At 77 light-years away, this star is considered a “dwarf” despite shining with a visible light almost 150 times that of Sol. The orange-red giant Arcturus and the blue white “dwarf” Regulus both share a common absolute magnitude very close to 0. The reason the two stars shine with a similar intrinsic brightness – despite widely different physical sizes – is Regulus’ photosphere is more than twice as hot (12,000 C) as Arcturus. While observing Regulus, look for a distant companion of magnitude 8.5. Normally low powers would best concentrate the companion’s light, but try a variety of magnifications to help improve contrast. For those with large aperture scopes, look for a 13.1 magnitude “companion’s companion” a little more than 2 arc seconds away!

Tuesday, April 10 – Be sure to get up before dawn to enjoy the Virginid meteor shower. The radiant point will be near Gamma in the bowl of Virgo. The fall rate of 20 per hour is above average for meteor showers, and with the Moon partially out of the equation this morning, you’re in for a treat!

Tonight, let’s have a look at Arcturus – a star whose distance from the Earth (10 parsecs) and radial velocity (less than 200 meters per second) can almost be considered a benchmark. By skydark you will see 0.2 magnitude, Arcturus – the brightest star in Bootes and 4th brightest star in the night sky – some 30 degrees above the eastern horizon. Apparent to the eye is Arcturus’ orange color. Because a star’s intrinsic luminosity relates to its apparent brightness and distance, Arcturus’ absolute magnitude is almost precisely the same as its apparent magnitude. Just because Arcturus’ radial velocity is nearly zero doesn’t mean it isn’t on the move relative to our Sun. Arcturus is now almost as close as it will ever get and its large proper motion – perpendicular to our line of sight – exceeds 125 kilometers per second. Every 100 years Arcturus moves almost 1 degree across the sky!

Since you’ve looked at a red star, why not look at a red planet before you call it a night? Mars is still making a wonderful apparition. Have you noticed it dimming even more? Right now it should be about magnitude -0.5. You may have noticed something else about Mars in the eyepiece, too… It’s getting smaller!

Wednesday, April 11 – Today is the birthday of William Wallace Campbell. Born in 1862, Campbell went on to become the leader of stellar motion and radial velocity studies. He was the director of Lick Observatory from 1901 to 1930, and also served as president of the University of California and the National Academy of Sciences. Also born on this day – but in 1901 – was Donald H. Menzel – assistant astronomer at Lick Observatory. Menzel became Director of Harvard Observatory, an expert on the Sun’s coronosphere and held a genuine belief in the extraterrestrial nature of UFOs. Today in 1960, the first radio search for extraterrestrial civilizations was started by Frank Drake (Project Ozma). In 1986, Halley’s Comet closed within 65 million kilometers of the Earth – as close as it would get.

Tonight, why don’t we honor Campbell’s work as we try taking a look at a variable ourselves? RT (star 48) Aurigae is a bright cephid that is located roughly halfway between Epsilon Geminorum and Theta Aurigae. This perfect example of a pulsating star follows a precise timetable of 3.728 days and fluxes by close to one magnitude.

Thursday, April 12 – Today in 1961, Yuri Gagarin made one full orbit of the Earth aboard Vostok 1, while also becoming the first human in space. Also today (in 1981) Columbia became the first Space Shuttle to launch.

Break out the telescope tonight and launch your way towards Iota Cancri – a fine wide disparate double of magnitudes 4.0 and 6.6 separated by some 30 arc seconds. This true binary is so distant from one another that they take over 60,000 years to complete a single orbit around their common center of gravity! Located slightly less than a fist’s width due north of M44, this pair is about 300 light years distant. Both stars shine with a light considerably brighter than our Sun and observers may note a subtle gold and pale blue color contrast between them.

Friday, April 13 – With no early evening Moon to contend with, this is a fine opportunity to have a look at a group of galaxies between Leo’s paws. Start at Regulus and look due east toward Iota Leonis. Halfway between the two (less than a fist from Regulus) and two finger-widths northeast of Rho Leonis, you’ll encounter Messier Galaxies M95 (Right Ascension: 10 : 44.0 – Declination: +11 : 42) and M96 (Right Ascension: 10 : 46.8 – Declination: +11 : 49) – both within the same low power field of view. At magnitude 9.2, the brighter – and slightly rounder – M96 lies northeast of 9.7 magnitude, M95. Pierre Mechain discovered both galaxies on March 20, 1781 and Messier added them to his catalog 4 days later. These two galaxies are two of the brightest members of the Leo I galaxy group located some 38 million light-years away.

To see another Messier member of the Leo I group, center on M96 and shift the galaxy south. From the north side of the low power field, the 9.3 magnitude galaxy M105 (Right Ascension: 10 : 47.8 – Declination: +12 : 35), nearby 10th magnitude NGC 3384 (Right Ascension: 10 : 48.3 – Declination: +12 : 38), and 12th magnitude NGC 3389 (Right Ascension: 10 : 48.5 – Declination: +12 : 32) will come into view. M105 was discovered by Mechain on the night Messier catalogued M95 and 96 but was not formally added to Messier’s catalog. Based on Mechain’s observing notes, Helen Sawyer Hogg added it to Messier’s list in 1947 – along with galaxy M106 and globular cluster M107. Mechain failed to notice M105’s bright neighboring galaxy – NGC 3384. NGC 3384 is actually slightly brighter than the faintest Messier discovered – M91.

We’re not done yet! If you center on M105 and shift due north less than a degree and a half you will encounter 10th magnitude NGC 3377 (Right Ascension: 10 : 47.7 – Declination: +13 : 59) – a small elongated galaxy with a stellar core. There are a dozen galaxies visible to moderate amateur instruments (through magnitude 12) in the Leo I region of the sky!

Saturday, April 14 – Today is the birthday of Christian Huygens. Born in 1629, the Dutch scientist went on to become one of the leaders in his field during the 17th century. Among his achievements were promoting the wave theory of light, patenting the pendulum clock, and improving the optics of telescopes by inventing a new type eyepiece and reducing false color through increasing the focal length of refractor telescopes. Huygens was the first to discover Saturn’s rings and largest satellite – Titan. Of the rings, Huygens said, “Saturn: encircled by a ring, thin and flat, nowhere touching, and inclined to the ecliptic.”

Wanna’ check Saturn out? It will be rising in the constellation of Virgo not long after the sky begins to turn dark. If you’re not sure of which “star” it is, just wait for awhile and you’ll find it about a fistwidth northwest of bright, blue/white Spica. Be sure to check out the ring system! Right now they have a very nice southern tilt which will allow you a great view of the shadow of the planet on the rings – and the shadow of the rings on the planet. If the atmosphere will allow, power up! Something you may never have thought of looking for could be happening… Can you see the planet’s edge through the Cassini division? Be sure to look for wide orbiting Titan and some of Saturn’s smaller moons slipping around the ring edges.

Tonight our challenge is also planetary – but it’s the planetary nebula – the “Ghost of Jupiter”. Begin by identifying the constellation of Hydra. Starting at Alpha Hydrae, head east about a fist’s width to find Lambda within a field of nearby fainter stars. Continue less than a fist southeast and locate Mu. You’ll find the “Ghost of Jupiter” (NGC 3242) lurking in the dark less than a finger-width due south. At magnitude 9, the NGC 3242 (Right Ascension: 10 : 24.8 – Declination: -18 : 38) gives a strikingly blue-green appearance in even small scopes – despite being more than 1500 light years away.

Sunday, April 15 – Tonight keep a watch for the “April Fireballs.” This unusual name has been given to what may be a branch of the complex Virginid stream which began earlier in the week. The absolute radiant of the stream is unclear, but most of its long tails will point back toward southeastern skies. These bright bolides can possibly arrive in a flurry – depending on how much Jupiter’s gravity has perturbed the meteoroid stream. Even if you only see one tonight, keep a watch in the days ahead. The time for “April Fireballs” lasts for two weeks. Just seeing one of these brilliant streaks will put a smile on your face!

And if you can’t take your eyes off Leo, then there’s good reason. The combination of Theta Leonis, Regulus and Mars certainly calls attention to itself!

While we’re out, let’s journey this evening towards another lovely multiple system as we explore Beta Monocerotis. Located about a fist width northwest of Sirius, Beta is one of the finest true triple systems for the small telescope. At low power, the 450 light year distant white primary will show the blue B and C stars to the southeast. If skies are stable, up the magnification to split the E/W oriented pair. All three stars are within a magnitude of each other and make Beta one of the finest sights for late winter skies.

If you hadn’t noticed, Saturn is at opposition tonight, meaning it will be viewable from dusk until dawn. Be sure to check out the “Ring King” – but wait until it has risen well above the lower atmosphere disturbance for a superior view!

Until next week, I wish you clear and steady skies!

Leo

[/caption]

Positioned directly on the ecliptic plane, Leo is a constellation of the zodiac preceded by Cancer to the west and followed by Virgo to the east. It is an ancient constellation, originally charted by Ptolemy and recognized by the International Astronomical Union as one of the 88 modern constellations. Leo spans 947 square degrees of sky and is the twelfth largest of all. It contains 3 bright stars and around 15 stars in its asterism, with 92 Bayer/Flamsteed designated stars within its confines. It is bordered by the constellations of Ursa Major, Leo Minor, Lynx, Cancer, Hydra, Sextans, Crater, Virgo and Coma Berenices. Leo is visible to all observers located at latitudes between +90° and ?65° and is best seen at culmination during the month of April.

There are five annual meteor showers associated with constellation Leo. The first is the Delta Leonid meteor stream which begins becoming active between February 5 through March 19 every year. The activity peaks in late February with no exact date, and the maximum amount of activity averages around 5 meteor per hour. The next date is April 17 and the Sigma Leonid meteor shower. Look for this rare occurrence to happen near the Leo/Virgo border. It is a very weak shower and activity rates no higher than 1 to 2 meteors per hour. The next is the most dependable shower of all – the November Leonids. The peak date is November 17th, but activity occurs around 2 days on either side of the date. The radiant is near Regulus and this is the most spectacular of modern showers. The year 1966 saw 500,000 per hour a rate of up 140 per second! Just a few years ago, in 2005 the rates were equally impressive. Why? Comet Temple-Tuttle is the answer. Whenever it nears perihelion, it adds fresh material to the stream and gives us a spectacular show. On the average, you can expect around 20 per hour between 33 year shows, but they are the fastest known at 71 kps. The last is the Leo Minorids which peak on or about December 14. This meteor shower was discovered by amateurs in 1971 and hasn’t really been confirmed yet, but do look for around 10 faint meteors per hour.

In Greek mythology, Leo was identified as the Nemean Lion, which may have been the source of the “tail” of the lion that killed Hercules during one of his twelve labors. While many constellations are difficult to visualize, Leo’s backwards question-mark is relatively easily to picture as a majestic lion set in stars. One of the reasons for its placement in the zodiac is possibly due to the fact that lions left their place in the desert for the banks of the Nile when the Sun was positioned in these stars. It is also possible that the Nile’s rise at this time and the lion’s migration is also the reason for the Sphinx to appear as it does – a leonine figure. The Persians called it Ser or Shir; the Turks, Artan; the Syrians, Aryo; the Jewish, Arye; the Indians, “Sher”; and the Babylonians, Aru — all meaning a lion. Early Hindu astronomers recognized it by regal names, as did other cultures. All befitting of the “King of Beasts”!

Let’s begin our tour by taking a look at the brightest star – Alpha Leonis – the “a” symbol on our map. Its name is Regulus and it is one hot customer when it comes to spin rate. Revolving completely on its axis in a little less than 16 hours, oblate Regulus would fly apart if it were moving any faster. Ranking as the twenty-first brightest star in the night sky, Alpha Leonis is a helium type star about 5 times larger and 160 times brighter than our own Sun. Speeding away from us at 3.7 kilometers per second, Regulus isn’t alone, either. The “Little King” is a multiple star system composed of a hot, bright, bluish-white star with a pair of small, faint companions easily seen in small telescopes. The companion is itself a double at around magnitude 13 and is a dwarf of an uncertain type. There is also a 13th magnitude fourth star in this grouping, but it is believed that it is not associated with Regulus since the “Little King” is moving toward it and will be about 14″ away in 785 years. Not bad for a star that’s been reigning the skies for around for a few million years!

Let’s fade east now, and take a look at Beta Leonis – the “B” symbol on our map. Its name is Denebola which means the “Lion’s tail” in Arabic. Located about 36 light years from Earth, this white class A dwarf star is more luminous than the Sun, emitting 12 times the solar energy and a Delta-Scuti type variable star. While that in itself isn’t particularly rare, what makes Denebola unusual is that it belongs to the Vega-class stars – ones that have a shroud of infra-red emitting dust around them. This could mean a possibility of planet forming capabilities! In binoculars, look for an optical double star companion to Beta. It’s not gravitationally, or physically related, but it’s a pleasing pairing.

Now, return to Regulus and hop up for Eta Leonis, the “n” symbol on our map. Eta is very special because of its huge distance – about 2100 light years from our solar system – and that’s only a guess. It is a supergiant star, and one that is losing its stellar mass at a huge rate. Compared to Sol, Eta loses 100,000 times more mass each year! Because of its position near the ecliptic plane, Eta is also frequently occulted by the Moon. Thanks to alert observers, that’s how we learned that Eta is also a very close binary star, too – with a companion only about 40% dimmer than the primary. Some time over the next 17 million years, the pair of red supergiant stars will probably merge to become a pair of massive white dwarf stars… or they may just blow up. Only time will tell…

Hop north for Gamma Leonis – the “Y” symbol on our map. Its name is Algeiba and it is a very fine double visual star for binoculars and and true binary star small telescopes. Just take a look at this magnificent orange red and and yellow pair under magnification and you’ll return again and again. The brighter primary star is a giant K type and orbiting out about four times the distance of Pluto is its giant G type companion. Further north you’ll find another excellent visual double star for binoculars – Zeta Leonis. It’s name is Aldhafera and this stellar spectral class F star is about 260 light years away.

Are you ready to try your hand at locating a pair of galaxies with binoculars? Then let’s try the “Leo Trio” – M65, M66 and NGC 3623. Return towards Beta and look for the triangular area that marks the asterism of Leo’s “hips”. If the night is suitable for binocular galaxy hunting, you will clearly see fifth magnitude Iota Leonis south of Theta. Aim your binoculars between them. Depending on the field of view size of your binoculars, a trio of galaxies will be visible in about one third to one fourth of the area you see. Don’t expect them to walk right out, but don’t sell your binoculars short, either. The M65 and M66 pair have higher surface brightness and sufficient size to be noticed as two opposing faint smudges. NGC 3623 is spot on the same magnitude, but is edge on in presentation instead of face-on. This makes it a lot harder to spot, but chances are very good your averted vision will pick it up while studying the M65/66 pair. The “Leo Trio” makes for a fine challenge!

Now let’s begin working with larger binoculars and small telescopes as we head for M96 galaxy group (RA 10h 46m 45.7s Dec +11 49′ 12″). Messier 96 is the brightest spiral galaxy within the M96 Group which includes Messier 95 and Messier 105 as well as at least nine other galaxies. Located about 38 million light years away, this group of galaxies with the Hubble Space Telescope and 8 Delta Cephei variable stars were found to help determine each individual galaxy’s distance. While you can’t expect to see each member in small optics, larger telescopes can hope to find elliptical galaxies NGC 3489 (11:00.3 +13:54), NGC 3412 (10:50.9 +13:25), NGC 3384 (10:48.3 +12:38) and NGC 3377 (10:47.7 +13:59), as well as barred spiral galaxy NGC 3299 (10:36.4 +12:42),

For an awesome spiral galaxy in a small telescope, don’t overlook NGC 2903 (RA 9:32.2 Dec +21:30). At a bright magnitude 9, you can often see this particular galaxy in binoculars from a dark sky site as well. Discovered by William Herschel in 1784, this beauty is often considered a missing Messier because it just so bright and conspicuous. As a matter of fact, the comet of 1760 passed it on a night Messier was watching and he didn’t even see it! For larger telescopes, look for NGC 2905 – a bright knot which is actually a star forming region in the galaxy itself with its own Herschel designation.

Before we leave, you must stop by NGC 3521 (RA 11:05.8 Dec -00:02). This 35 million light year distant spiral galaxy is often overlooked for no apparent reason – but it shouldn’t be. At a very respectable magnitude 9, you can often find this elongated gem with the bright nucleus in larger binoculars from a dark sky site and you can easily study spiral galaxy structure with a larger telescope. Look for an inclined view with patchiness in the structure that indicates great star forming regions at work. Its stellar counter rotation is being studied because it has a bar structure that we are seeing “end on”!

This doesn’t even begin to scratch the surface of what you can find on Leo’s hide. Be sure to get yourself a good star chart or sky atlas and go lion taming!

Sources: SEDS, Wikipedia
Chart Courtesy of Your Sky.