This article originally appeared in 2009, but I’ve updated it and added this video.
The ground feels firm and solid beneath your feet. Of course, the Earth is rotating, turning once on its axis every day. Fortunately gravity keeps you firmly attached to the planet, and because of momentum, you don’t feel the movement – the same way you don’t feel the speed of a car going down the highway. But how fast does the Earth rotate?
You might be surprised to know that a spot on the surface of the Earth is moving at 1675 km/h or 465 meters/second. That’s 1,040 miles/hour. Just think, for every second, you’re moving almost half a kilometer through space, and you don’t even feel it.
Want to do the calculation for yourself? The Earth’s circumference at the equator is 40,075 km. And the length of time the Earth takes to complete one full turn on its axis is 23.93 hours.
Wait, 23.93 hours? Isn’t a day 24 hours? Astronomers calculate a day in two ways. There’s the amount of time it takes for the Earth to complete one full rotation on its axis, compared to the background stars. Imagine you were looking down at the Earth from above the North Pole. You’d see the Earth turn once completely in 23 hours and 56 minutes. Astronomers call this a sidereal day.
And then there’s the time it takes for the Sun to return to the same spot in the sky. Since the Earth is orbiting the Sun, we actually need an extra 4 minutes each day to return the Sun to the same spot. Astronomers call this a solar day.
Then we divide the length of a day into the distance a point on the equator travels in that period: 40,075 km/23.93 hours = 1,675 km/hour, 465 meters/second.
The speed of the Earth’s rotation changes as you go North or South away from the equator. Finally, when you reach one of the Earth’s poles, you’re taking a whole day to just turn once in place – that’s not very fast.
Because you’re spinning around and around on the Earth, there’s a force that wants to spin you off into space; like when you spin a weight on a string. But don’t worry, that force isn’t very strong, and it’s totally overwhelmed by the force of gravity holding you down. The force that wants to throw you into space is only 0.3% the force of gravity. In other words, if the Earth wasn’t spinning, you would weigh 0.3% more than you do right now.
Space agencies take advantage of the higher velocities at the Earth’s equator to launch their rockets into space. By launching their rockets from the equator, they can use less fuel, or launch more payload with the same amount of fuel. As it launches, the rocket is already going 1,675 km/hour. That makes it easier to reach the 28,000 km/hour orbital velocity; or even faster to reach geosynchronous orbit.
We have written many articles about the Earth for Universe Today. Here’s an article about why the Earth rotates.
The Sun is about to come up over the South Pacific Ocean in this colorful scene photographed by one of the Expedition 35 crew members aboard the International Space Station between 4 and 5 a.m. local time, May 5, 2013. Credit: NASA
Today’s NASA Image of the Day is just plain pretty; pretty as a postcard. All it is missing is the “Wish you were here!” sentiments.
Glowing trails seen in the early morning sky over the Marshall Islands (NASA/Jon Grant)
Ball lightning? Spectral orbs? Swamp gas? Early this morning, May 7, these eerie glowing trails were seen in the sky above the Marshall Islands and were captured on camera by NASA photographer John Grant. Of course, if NASA’s involved there has to be a reasonable explanation, right?
For a larger image (and to see what really caused the trails) click below:
Credit: NASA/John Grant
Although it might look like cheesy special effects, these colorful clouds are actually visible trails that were left by two sounding rockets launched from Roi Namur in the Marshall Islands, at 3:39 a.m. EDT on May 7. The rockets were part of the NASA-funded EVEX experiment to study winds and electrical activity in the upper atmosphere.
The red cloud was formed by the release of lithium vapor and the white-and-blue tracer clouds were formed by the release of trimethyl aluminum (TMA). These clouds allowed scientists on the ground from various locations in the Marshall Islands to observe neutral winds in the ionosphere.
“Neutral winds are one of the hardest things to study,” said Doug Rowland, an EVEX team member at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “One can’t physically see the wind, and it is difficult to measure from the ground, so we use the TMA as a tracer.”
Launch of the second EVEX rocket on the morning of May 7. The plume from the first is visible on the left. (NASA/John Grant)
The EVEX (Equatorial Vortex Experiment) rockets were launched 90 seconds apart. By staggering the launches the two rockets were able to gather data simultaneously at two altitudes through the ionosphere.
Beginning about 60 miles (96 km) up, the ionosphere is a crucial layer of charged particles surrounding our planet. This layer serves as the medium through which high frequency radio waves – such as those sent down to the ground by satellites – travel. Governed by Earth’s magnetic field, high-altitude winds, and incoming material and energy from the sun, the ionosphere can be calm at certain times of day and at other times turbulent, disrupting satellite signals.
The EVEX experiment is designed to measure events in two separate regions of the ionosphere to see how they work together to drive it from placid and smooth to violently disturbed. Such information could ultimately lead to the ability to accurately forecast this important aspect of space weather.
A GROVER prototype during testing in January 2013. Credit: Gabriel Trisca, Boise State University
How fast is Greenland’s ice sheet melting in response to climate change, and how is it recovering? A new NASA rover with the friendly name of GROVER (Greeland Rover and Goddard Remotely Operated Vehicle for Exploration and Research) is going to try to figure that out.
GROVER will rove across a small area of the massive ice sheet at a location called Summit Camp, which is a National Science Foundation outpost. On board it has ground-penetrating radar that is intended to figure out how the snow builds up in layers through time.
“Robots like GROVER will give us a new tool for glaciology studies,” stated Lora Koenig, a glaciologist at Goddard and science advisor on the project.
A prototype of GROVER during testing in January 2012. The rover does not have its solar panels attached here. The laptop was used as part of that specific test only. Credit: Gabriel Trisca, Boise State University
The student-designed project came to be during development phases in 2010 and 2011, principally at Boise State University in Idaho. At six feet tall, it’s way more massive than its Sesame Street namesake: it tips the scale at 800 pounds, including solar panels, and has two snowmobile tracks built in to move around.
“GROVER is just like a spacecraft but it has to operate on the ground,” stated Michael Comberiate, a retired NASA engineer and manager of Goddard’s Engineering Boot Camp.
“It has to survive unattended for months in a hostile environment, with just a few commands to interrogate it and find out its status and give it some directions for how to accommodate situations it finds itself in.”
Studies began on May 3 and will continue through June 8.
If you couldn’t tell, we love time-lapse videos… whether they’re made of photos looking up at the sky from Earth or looking down at Earth from the sky! This latest assembly by photographer Bruce W. Berry takes us on a tour around the planet from orbit, created from images taken by astronauts aboard the International Space Station and expertly de-noised, stabilized and smoothed to 24 frames per second. The result is — like several others before — simply stunning, a wonderful reminder of our place in space and the beauty of our living world.
SpaceShipTwo fires her rocket motor in flight for 1st time on April 29, 2013. Credit: MarsScientific.com
SpaceShipTwo fires her rocket motor in flight for 1st time on April 29, 2013. Credit: MarsScientific.com Updated with more Photos & Video[/caption]
In a momentous and long awaited day in spaceflight, Virgin Galactic’s SpaceShipTwo (SS2) commercial spaceliner named “Enterprise” lit up her hybrid rocket engines in flight and reached supersonic speeds for the first time in history, today, Monday, April 29, 2013 – in the skies over the Mojave Desert in California.
“What a feeling to be on the ground with all the team in Mojave to witness Virgin Galactic go faster than the speed of sound,” wrote Virgin Galacic founder and owner, billionaire Sir Richard Branson, a short while ago.
Branson wants to bring the incomparable joys of human spaceflight– including weightlessness and spectacular views of the Earth’s curvature- to the masses. Thus making science fiction fantasies of the future like “2001: A Space Odyssey” and “Star Trek” a reality – TODAY!
“This is a momentous day and the single most important flight test to date for our Virgin Galactic program,” said Branson from the Mojave Air and Space Port. “What a feeling to be on the ground with all the team in Mojave to witness Virgin Galactic go faster than the speed of sound.”
ShaceShipTwo from Virgin Galactic fires its rocket engines for the first time in history on April 29, 2013 to achieve supersonic speed. Credit: Virgin Galactic
The SpaceShipTwo test of Virgin Spaceship Enterprise was conducted by builder Scaled Composites, led by famed aerospace engineer Burt Rutan, and Virgin Galactic.
With Scaled Composites test pilots Mark Stucky and Mike Alsbury at the helm, the engine burn lasted about 16 seconds, exactly as planned and achieved a speed of Mach 1.2 – breaking the sound barrier!
Watch this video of today’s SS2 rocket test flight:
The test flight began at about 7:02 a.m. local California time as SpaceShipTwo took off from Mojave strapped to the belly of the WhiteKnightTwo (WK2) mothership.
SS2 was released from the mothership at an altitude of 47,000 feet (14 km) some 45 minutes into the flight.
“The pilots triggered ignition of the rocket motor, causing the main oxidizer valve to open and igniters to fire within the fuel case. At this point, SS2 was propelled forward and upward to a maximum altitude of 55,000 feet [17 km],” said Virgin Galactic in a statement.
SS2 is powered by RocketMotorTwo, developed by Sierra Nevada Corporation – which is also constructing the manned DreamChaser mini shuttle ‘space taxi’ under contract to NASA and aiming to restart launches of American astronauts from American soil to low Earth orbit and the ISS.
Boom camera shot of SpaceShipTwo breaking the sound barrier. Credit: Virgin Galactic
“The first powered flight of Virgin Spaceship Enterprise was without any doubt, our single most important flight test to date,” said Branson, who watched the flight from the grounds of Mojave.
The entire fight lasted about an hour with SS2 gliding back for a safe landing at the Mojave Air and Space Port to conclude the history making flight.
Until today’s engine firing, the SS2/WK2 aerial test flight program had been limited to captive carry and landing drop tests.
Branson’s near term goal is for SpaceShipTwo to fly to space – commonly defined as 62 miles (100 km) altitude – for the first time before year’s end, validate the vehicle with a rigorous test flight program of gradually expanding the flight envelope to insure full operability and safety and then carry the first revenue paying passengers to space thereafter from Spaceport America in New Mexico.
“For the first time, we were able to prove the key components of the system, fully integrated and in flight. Today’s supersonic success opens the way for a rapid expansion of the spaceship’s powered flight envelope, with a very realistic goal of full space flight by the year’s end. We saw history in the making today and I couldn’t be more proud of everyone involved.”
Rumors that this rocket firing test flight was imminent had reached a fever pitch over the past few days, stoked by broad hints in open messages from Branson himself. So, a large group of Virgin employees and space enthusiasts were present today to witness the momentous event (see photos).
Sir Richard Branson hugs designer Burt Rutan as they are surrounded by employee’s of Virgin Galactic, The SpaceShip Company and Scaled Composites watch as Virgin Galactic’s SpaceShip2 streaks across the sky under rocket power, its first ever since the program began in 2005. Burt’s wife Tonya Rutan is at right taking their photo. The spacecraft was dropped from its “mothership”, WhiteKnight2 over the Mojave, CA area, April 29, 2013 at high altitude before firing its hybrid power motor. Virgin Galactic hopes to become the first commercial space venture to bring multiple passengers into space on a regular basis.
In the not too distant future, the purpose of SS2 is for everyday folks – not just highly trained astronauts – to experience spaceflight and out of this world views of the Earth below and the heavens above.
Eventually, human spaceflight could be as commonplace as flying aboard a commercial jetliner is today.
SpaceShipTwo can carry 8 people total; including a crew of two pilots and six passengers on suborbital missions to space.
Although SS2 cannot go into Earth orbit, Branson hopes that future varients will achieve orbit.
Branson himself will fly aboard the first commercial SS2 flight. Over 500 people have already plucked down over $200,000 to reserve the unprecedented choice seats.
“Like our hundreds of customers from around the world, my children and I cannot wait to get on board this fantastic vehicle for our own trip to space and am delighted that today’s milestone brings that day much closer,” said Branson.
The Commercial Spaceflight Federation quickly lauded the Virgin Galactic team and issued this statement:
“The Commercial Spaceflight Federation congratulates the team at Virgin Galactic and Scaled Composites for the first powered test flight of SpaceShipTwo today,” said CSF President Michael Lopez-Alegria.
“This incredible achievement is the direct result of the hard work and dedication by these two companies, as well as by RocketMotorTwo developer Sierra Nevada Corporation. Because of their efforts, we are one step closer to achieving safe, routine, and cost-effective access to space that will create abundant opportunities for space-based research and that will inspire the next generation of engineers and scientists. I applaud the team at Virgin Galactic and Scaled Composites for their accomplishment, and the team at Mojave Air & Space Port for their efforts in creating a professional and safe testing environment.”
In this era of stingy federal funding and slashes to NASA’s budget, commercial spaceflight will play a major and increasing role in bringing down the high costs of access to space as well as enabling an expanding science exploration program and private commercial space exploitation programs to open up the High Frontier.
Other private companies like SpaceX and Orbital Sciences are already leading the charge with regards to the commercial space exploration race with their Falcon 9 and Antares commercial rockets – now launching crucial cargo for NASA to the International Space Station (ISS) since the retirement of the Space Shuttle orbiters in 2011.
A false-color image, taken by the Cassini spacecraft, of a huge hurricane at Saturn's north pole. Credit: NASA/JPL-Caltech/SSI
Checking out the above pictures of a Saturn hurricane, one can’t help but wonder: how close was the Cassini spacecraft to spiralling down into gassy nothingness?
These dizzying images of a hurricane on Saturn, of course, came as the spacecraft zoomed overhead at a safe distance. NASA’s goal in examining this huge hurricane is to figure out its mechanisms and to compare it to what happens on our home planet.
Hurricanes on Earth munch on water vapor to keep spinning. On Saturn, there’s no vast pool of water to draw from, but there’s still enough water vapor in the clouds to help scientists understand more about how hurricanes on Earth begin, and continue.
“We did a double take when we saw this vortex because it looks so much like a hurricane on Earth,” stated Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn’s hydrogen atmosphere.”
A false-color view of Saturn’s storm, as seen through Cassini’s wide-angle camera. You can see the eye in dark red, the jet stream in yellowish-green, and low-lying clouds in orange. The blue bands at the edge are Saturn’s rings. Credit: NASA/JPL-Caltech/SSI
There’s one big change in hurricane activity you’d observe if suddenly shifted from Earth to Saturn: this behemoth — 1,250 miles (2,000 kilometers) wide, about 20 times its Earthly counterparts — spins a heckuva lot faster.
In the eye, winds in the wall speed more than four times faster than what you’d find on Earth. The hurricane also sticks around at the north pole. On Earth, hurricanes head north (and eventually dissipate) due to wind forces generated by the planet’s rotation.
“The polar hurricane has nowhere else to go, and that’s likely why it’s stuck at the pole,” stated Kunio Sayanagi, a Cassini imaging team associate at Hampton University in Hampton, Va.
Cassini initially spotted the storm in 2004 through its heat-seeking infrared camera, when the north pole was shrouded in darkness during winter.
The spacecraft first caught the storm in visible light in 2009, when NASA controllers altered Cassini’s orbit so that it could view the poles.
Saturn, of course, is not the only gas giant in the solar system with massive hurricanes. Jupiter’s Great Red Spot has been raging since before humans first spotted it in the 1600s. It appears to be shrinking, and could become circular by 2040.
Neptune also has hurricanes that can reach speeds of 1,300 miles (2,100 kilometers) an hour despite its cold nature; it even had a Great Dark Spot spotted during Voyager’s flypast in 1989 that later faded from view. Uranus, which scientists previously believed was quiet, is a pretty stormy place as well.
Check out this YouTube video for more details on how Saturn’s storm works.
Saunders Island and Wolstenholme Fjord with Kap Atholl in the background photographed during a NASA IceBridge flight. (NASA/Michael Studinger)
It’s quite a long way from Mars, but I can’t help but be reminded of the Red Planet’s ice-covered north pole when looking at this photo taken by Michael Studinger earlier this month, during a recent IceBridge survey flight over Greenland.
Called Saunders Island (also Appat Island) the 82-square-mile frozen slab of rock rises from the sea off the coast of northwestern Greenland, one of many islands within the Wolstenholme (Uummannaq) Fjord on the shore of Baffin Bay. Operation IceBridge, a six-year aerial survey of the changing ice coverage at our planet’s poles, is run by NASA to provide valuable ground-level information to supplement satellite data.
To me, the shape of the island’s steep rock faces and rugged inlets slice into its interior bear a striking resemblance to Mars’ ice cap.
Mars’ north polar ice cap
While Mars’ ice cap is shaped by very different processes — and obviously much bigger — you might see the connection too!
But rather than dark Martian dunes, sea ice can be seen surrounding the islands in varying thicknesses in the IceBridge photo above. Sea ice coverage in the fjord ranges from thicker, white ice in the background to thinner “grease” ice and leads with dark, open ocean water in the foreground.
The IceBridge P-3B airborne laboratory in a hangar at Wallops Flight Facility (NASA/George Hale)
As the amount of darker, ice-free water surfaces increase over the course of the year due to rising global temperatures, the more heat from solar radiation is collected in the ocean — thus speeding up the process of seasonal sea ice loss and overall Arctic warming.
Read more about the IceBridge mission here, and see a collection of more photos from this season’s flights here.
NASA’s Operation IceBridge images Earth’s polar ice in unprecedented detail to better understand processes that connect the polar regions with the global climate system. IceBridge utilizes a highly specialized fleet of research aircraft and the most sophisticated suite of innovative science instruments ever assembled to characterize annual changes in thickness of sea ice, glaciers, and ice sheets. In addition, IceBridge collects critical data used to predict the response of earth’s polar ice to climate change and resulting sea-level rise.
'A glance out the Space Station window is worth taking,' said ISS commander Chris Hadfield, of this image taken on Earth Day, April 22, 2013. Credit: NASA/CSA.
After Canadian astronaut Chris Hadfield arrived at the International Space Station in December 2012, he quickly became an internet sensation with all the tweets, Facebook and G+ posts he shared providing in inside look at living and working in space. But the biggest draw is all the incredible images he has shared throughout his ISS mission. In this video, Hadfield takes you to the best seat in the house – the Cupola on the ISS — to gaze at the visual splendor of the Earth. He shares his techniques and his passion for capturing the fleeting glimpses of our changing world.
UPDATE: NASA also chimed in for Earth Day with this video from astronaut Don Pettit sharing his images and tips for photography of Earth from space:
Do you know how much material falls onto Earth from space every day? How many different species there are in the ocean? How far the continents move every year? In honor of Earth Day here’s a very cool infographic that answers those questions about our planet — and 47 more!
Check out the full version below:
And for more interesting information about our planet, click here and here.
