You know what? Our planet is awesome.
[Click to thalassenate.]
This photo was taken by ESA astronaut André Kuipers, on board the International Space Station. Frustratingly there’s no info I could find on when this was taken, or what part of the planet it shows… but then, in a way, maybe that’s OK. It’s a reminder of how big Earth is, how easy it is to get lost here, and how much of it there’s still to explore.
Of course, that glint we see of reflected sunlight can tell us so much. It tells us we live on a world of water, which we already knew. But sometimes we see glints from alien worlds, and that tells us liquid exists there too.
And that tells me to take nothing for granted. Even the simplest thing we see so often can reveal amazing knowledge of things we’d otherwise never see.
I’ve been posting a lot about Mars lately – and stay tuned, there’s plenty more! – but let’s not forget the first planet we ever viewed from space: our own. Here’s another lovely time lapse video of Earth made from images taken by astronauts aboard the International Space Station, called Earth Illuminated.
Regular readers might recognize some of the clips used here; for example the opening shot shows the solstice Sun not quite setting over the limb of the Earth. Many of the other features you can see in this video I’ve explained before too, like air glow, aurorae, and cities from space. Still, it’s nice to see them again, some literally in a different light.
Tip o’ the spacesuit visor to Dan Gillmor on G+.
Well folks, it’s been a while, so it’s time for a good ol’ fashioned BA debunking.
This morning I got an email from BABloggee Joshua Frost as well as a note on Twitter from scifi author Diane Duane telling me about a picture making the rounds on teh interwebz, purporting to be taken from Mars. It shows the Martian landscape at twilight, and claims that the three lights in the sky are Earth, Venus, and Jupiter:
Pretty, isn’t it? You can find endless copies of it online; just search on the term "mars skyline". It’s been picked up on tons of Tumblrs and other social media.
But yeah, there’s just one problem: it’s not real.
I knew right away it wasn’t legit, but it’s hard to say exactly how. I’ve run into this problem before; I have a lot of experience looking at space images, and you just get a sense of what’s real and what isn’t. This one screams fake. The landscape color is a bit too saturated for Mars*. The sky’s the wrong color. The clouds are too numerous, the wrong color as well, and they have that "rendered by software" look to them.
But that’s not proof, of course. Gut sense may not be a bad place to start, but it makes for lousy evidence. The thing is, there is solid evidence the picture isn’t real! Look to the lower left corner of the image; see the letters there? Here’s a zoom:
See? The arrow points to the letters, and I zoomed in and enhanced the brightness and contrast a bit. The letters are "NE". As in, "northeast".
This is exactly what you see when you use planetarium software on a computer to display the sky. Programs like Starry Night, SkySafari, and so on will put the cardinal directions (north, south, and so on) along the horizon to indicate what direction you’re looking. And many of them will display the appearance of the sky from other planets. It’s clear that’s what we have here: a rendered view from Mars using planetarium software. I’m not sure which one (there are quite a few packages available) but I bet someone out there in BAland would recognize it. Any takers?
Interestingly, fiddling with some of software I have that displays solar system planetary positions, I found that a couple of years ago (mid-2010) the view from Mars right after sunset would show Venus, Earth, and Jupiter lined up something like that. Had you been on Mars looking west you would’ve seen something very much like the vista in the picture. Thing is, had one of the rovers taken this picture, it would’ve been all over the web at the time… including here on Bad Astronomy. I wouldn’t have passed up the chance to post a picture that cool. [Note: there is a real picture of the Earth seen by a Mars rover: from Spirit, in 2004, inset above.]
Mind you, the picture itself isn’t a hoax! It’s just a computer generated image probably meant to represent a real scene. But it got spread around the net, and before you know it people think it’s real.
I’ll note that I love that people think images like this are so beautiful and interesting that they pass them around and get a sense of wonder from them. But it bugs me that it’s possible that an unreal picture gets treated as real. In this case there’s no harm done, but it’s not hard to imagine a case where a forged image showing something damaging to someone’s reputation gets treated as real and spreads like wildfire. It’s happened before, many times.
The problem here is that people pass it from one place to another without attribution, without a link to the original source (usually it’s linked to the place they got it from, one link down the line in a very long chain). In this case, I searched for a while and still have no idea where the original for this came from. It got picked up wholesale from blog to blog and Tumblr to Tumblr so rapidly that the pedigree of it got lost. Maybe someone more patient than me can find the source.
I’ve been fooled on Twitter by fake posts before, too. Everyone has at some point. I’m just glad to be able to interject a little dose of reality in this case.
And remember: we have actual, real, amazing, breath-taking images coming from Mars right now. And the fact that they are real, and mean we have a presence on another world, is far more moving and stirring than any fake could ever be.
* I’ll note that the color of the landscape in the picture does look similar to that from the old Viking images of Mars from the 1970s. The color of those images was probably too saturated when displayed, in my opinion; getting the color right in those old shots was actually fairly tough.
- An unreal picture of sunset at the north pole
- A fake and a real view of the solar eclipse… FROM SPACE!
- NASA FAKED A SHUTTLE IMAGE!!!!! (a joke post I put up that some folks took seriously; see the followup post for more silliness)
- Holy UFO hoax!
- Latvian meteorite impact: fake
On July 5, 2012, the European Space Agency launched the Meteosat Second Generation-3 (MSG-3) weather satellite into a geosynchronous orbit about 40,000 kilometers above the Earth. It has several cameras on board, including the Spinning Enhanced Visible and Infrared Imager (SEVIRI) that takes (duh) visible and infrared pictures in 12 different wavelengths (colors). The first image from that camera was just sent back, and it’s an incredibly beautiful shot of our home world:
[Click to enterranate, and holy cow do you want to.]
There is nothing about this picture I don’t love. I think my favorite part is South America, on the left, coming out of night time and into the dawn. But the chains of clouds over Africa are a close second.
SEVIRI has a resolution of 1-3 kilometers, and can take these amazing full-disk shots of Earth. It also has a detector that can measure the amount of sunlight reflecting off the Earth as well as infrared light radiated by the Earth, which are critical measurements needed to better understand global warming. Interestingly, it also has a search and rescue transponder that acts as a relay for emergency distress signals.
MSG-3 is the third of four second generation METEOSAT satellites launched by the ESA; a third generation is even now being designed.
Everything this and the other MSG satellites do is important to our understanding of weather and climate, of course, and I’m glad these are being built and flown. But it doesn’t hurt to also just marvel at the stunning pictures they send us.
Image credit: Eumetsat
Today – July 5, 2012 – at about 04:00 UTC (a few hours ago as I write this) the Earth reached aphelion, the point in its elliptical orbit when it’s farthest from the Sun.
According to the US Naval Observatory, we were 1.016675058 Astronomical Units from the Sun at that time. An AU is the average distance from the Earth to the Sun, and is defined as 149,597,870.7 kilometers (92,955,807.2 miles).
That means that at aphelion the center of the Earth was 152,092,424 km (94,505,851 miles) from the center of the Sun.
Over the next six months we’ll slowly approach the Sun again until we reach perihelion – the closest point in the Earth’s orbit to the Sun – on January 2, 2013, at about 05:00 UTC.
When we’re farther from the Sun it appears a little bit smaller in the sky, but you’d never notice. For one thing, staring at the Sun is a bad idea! For another, the change is so slow day by day that it’s impossible to notice anyway. For a third thing, the total change over the course of six months isn’t very big either. Astronomer (and friend of the blog) Anthony Ayiomamitis took two pictures that show this:
These are from aphelion and perihelion in 2005, but the scale is always about the same every year. As you can see, the change in the Sun’s size isn’t terribly big.
So even though you may not notice it, it’s still neat to think that after the past 183 days or so we’ve been steadily moving farther from the Sun, and now we’re on our way back in. And even neater… the Earth has done this over four and half billion times before. So it has some experience here.
Today, June 20, at 23:09 UTC (7:09 p.m. Eastern US time), the Earth’s north pole will be tipped over toward the Sun as far as it can for the year. There are other ways to describe it — the Sun reaches its maximum declination, its annual northern movement in the sky peaks, it’s the longest day of the year — but most folks just call it the summer solstice.
You can use this event to measure
your latitude the Earth’s tilt, if you have a stick and a protractor and clear skies and the ability to take an inverse tangent. Or you can read about past summer solstices here, here, here, and here (or the winter solstice here, here, here, here, here, here and here).
Or you can celebrate by checking out the gallery below of some of my favorite pictures of the Sun. If it’s cloudy where you are, or you’re in the southern hemisphere where it’s the winter solstice today, then maybe that’ll help spill a little golden glow into your day.
And finally, think on this: the Earth has had well over 4.5 billion summer solstices since it formed. And it’ll have billions more! Just a little perspective to your day, care of the Universe.
Use the thumbnails and arrows to browse, and click on the images to go through to blog posts with more details and descriptions.
The Solar Dynamics Observatory is a NASA satellite that observes the Sun 24 hours a day. It orbits the Earth, placed carefully so that it takes 24 hours to circle the Earth once — what we call a geosynchronous orbit. This maximizes its output, and allows scientists to squeeze as much data from it as possible.
But, twice a year, the geometry of SDO’s orbit aligns in such a way that the Earth itself gets between the observatory and the Sun. When that happens, you get an eclipse! We’re in one of those "eclipse seasons" now, and around midnight last night UTC one such eclipse occurred. The folks at SDO created a nifty video from the images collected during that time:
That’s cool. You can see the Earth barreling through the image, blocking SDO’s view. SDO has several different cameras which look at the Sun at different wavelengths of ultraviolet and optical light. The first view, colored red, is actually in ultraviolet (at 304 Angstroms, if you’re keeping track). The next view, colored gold, is even further in the UV (193 Angstroms). Then they cycle through a bunch of different wavelengths, giving a psychedelic journey through an eclipse that reminds me of the ferry ride from "Willy Wonka".
"There’s no earthly way of knowing, which direction we are going…"
I’ve written about all this before; see Related Posts below for more.
And I’ll leave you with this question: when the Moon passes between the Earth and the Sun, it’s a solar eclipse, and when the Earth passes between the Sun and the Moon, it’s a lunar eclipse. So what do we call it when, for us on the surface, the Earth gets in between us and the Sun?
Tip o’ the dew shield to Camilla Corona SDO on Google+.
Last week, I posted an exceptional image of our home world as seen by the Suomi NPP Earth-observing satellite. The image was so popular that NASA released a second one, this time of the Eastern hemisphere, showing once again why it’s called the Blue Marble:
[Click to engaiaenate, or grab the terrestrialicious 11,500 x 11,500 pixel shot].
Like the other one, this is a mosaic, created over six different orbits — the bright north/south swaths are actually the reflection of the Sun in the ocean as the satellite passed over that area multiple times.
Although the satellite is in low Earth orbit, just a few hundred kilometers off the surface, the images have been mosaicked together to represent the view as if you were about 13,000 km (8000 miles) away. You’re seeing most of but not quite all of the entire hemisphere here. The inset image shows why; the farther you are from Earth the more of it you see.
If you’re having a hard time picturing that, imagine taking a camera and holding it a couple of centimeters from your floor. You only see a small section of the floor, right? Now take hundreds of pictures, moving the camera each time to get a different part of the floor. If you stitch those pictures together you have a complete image of your floor, even though it was too big to see from any individual shot. It’s as if you were hovering over the floor from higher up and took one shot.
That’s how this was done as well, though the pictures couldn’t just be stitched together; they had to be warped a bit to account for the Earth being round (near the Earth’s limb you’re seeing the ground at more of an angle than what’s directly below you). That’s why the image gives you such an overwhelming feeling of perspective, of actually being over the planet from all those thousands of kilometers away.
And I wonder… someday, our children may get this view every day, just by looking out a window. Every time I think about that, I get a chill. When I was a kid, that thought was science fiction. Now it’s maybe just a few more years down the road.
[UPDATE: Right after posting this, I got a feeling of deja-vu, and suddenly realized where I've seen this view of the Earth before: Apollo 17. What I wrote in that last paragraph is literally true: humans have seen this view before, and I hope that one day it will be routine to see it this way once again.]
Image credit: NASA/NOAA.
Thanks to astronaut Ron Garan on Google+, I was alerted to some amazing footage of the Moon setting as seen by astronauts on board the International Space Station. I uploaded it to YouTube and added some comments to show you something really cool…
[Set it to high-def and make it full screen!]
Astonishing, isn’t it? As the Moon sets, you’re seeing it through thicker and thicker air. The air acts like a lens, bending the light upward. The part of the Moon nearer the Earth’s limb gets bent up more, so the Moon looks like it’s getting flattened. Watch it again; the top of the Moon doesn’t appear to be affected much. It looks more like the bottom slows down and the top pushes into it. You can read about this effect in more detail in an earlier blog post.
Weirdly, as I watched the video, it looked very much like the whole Moon was shrinking as it set, as if it were receding rapidly. When I saw that I knew intuitively that couldn’t be real; the ISS is only moving a few thousand kilometers over the time this whole video was taken (about ten minutes), not nearly enough to see that big a change in the size of the Moon. It’s 400,000 kilometers away, after all! So I measured the size of the Moon on the screen, and incredibly the width doesn’t change. Do you see it appear to shrink too? It’s an illusion!
Funny how our brain interprets such things. As if seeing a gigantic rock moving through the sky while perched on board a football-field sized satellite moving at 30,000 km/hr isn’t weird enough!
Credit: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth".
Just before Halloween last year, NASA launched into orbit the improbably named National Polar-orbiting Operational Environmental Satellite System Preparatory Project, which they thankfully shortened to NPP. In its low 800 km (500 mile) orbit it looks down at the Earth to investigate our environment. It only sees a portion of the Earth at any one time, but if you take observations taken during a single day — say, on January 4, 2012 — and stitch them all together, you get this magnificent shot:
[Click to engaiaenate, or download the Big McLarge Huge 8000 x 8000 pixel version.]
Man, the resolution is so high is like you’re actually there.
In fact, the biggest version is 8000 pixels across, and the Earth is about 8000 miles wide, so the resolution is about a mile per pixel. We’re not seeing the entire hemisphere here, but the view is roughly 8000 km across (judging from the size of the US compared to the view). The big image is 8000 pixels wide, so the resolution of that mosaic is about 1 km/pixel. The Earth is big.
NPP was recently renamed Suomi NPP in honor of Verner Suomi, a pioneer in using satellites in meteorology. I like that we tend to name satellites and space probes after people whose work made those very missions possible, or for people we honor and respect (my favorite is still Sojourner, the Mars rover named after Sojourner Truth… with the bonus of the name being a pun).
Apropos of nothing, I’ll note the images making up this seamless mosaic were taken around the same time the Earth was at perihelion, when it was closest to the Sun in its orbit. There is nothing particularly important about that fact, but still… when I see pictures like this I think about how amazing our planet is, and how wonderfully well-adapted we are to it. Evolution is a stochastic process, a semi-random series of bumps and false starts that literally made us who were are today. But that doesn’t change the feeling of comfort I get when I see a picture of Earth, floating in space, sitting in the brightest and warmest sunlight of the year.
It’s home, and I’m glad we’re taking such a close look at it.