On Tuesday Curiosity decided its path for the first time on its way to Mt. Sharp. Using autonomous navigation or autonav, Curiosity drove onto ground that had not been confirmed safe by NASA’s Curiosity science team. To determine its path, the rover takes several pictures and its computer processes the information to map any dangerous or rough terrain. This allows Curiosity to safely travel even beyond the area that its team of drivers on Earth can evaluate ahead of time. Similar technology is used on “driverless” cars such as those that can park themselves or stop before hitting an object.
Monthly Archives: August 2013
Night Sky Objects to Find this Weekend!
Take advantage of the Labor Day weekend to observe a number of early morning celestial objects. Beginning early September, Comet ISON is low in the east before dawn in the constellation Cancer the Crab. Right now however, you’ll need good size telescope to observe the comet, which appears as a soft, fuzzy glow, but even without a telescope there’s a pair of very visible planets low in the eastern sky just before sunrise. Near the horizon is Mars – bright orange in color, while brillant Jupiter shines just above Mars. And while you’re at it, look for a very pretty compact star cluster, known as the Beehive star cluster, nearby Mars. Observing the morning sky won’t be disappointing – all good reasons for getting up early, early in September.
Stars: A Size Comparison
When people find out that I work in a planetarium they sometimes have questions. Some of the most frequently asked questions is about stars: what are they, how far away are they, are they explosions or just balls of burning gas.
Basically, what is up with those things we call stars?
Most of the time people think that every star they see in the sky is just like our own star, the Sun. They know the Sun is a star and that it appears to be larger than the other stars because it is so close to us. The other stars in the sky are further away, obviously, but they just assume that they’re still relatively the same size as our own Sun. It’s true that they’re all far away (in varying degrees) but it’s not true that they’re all the same size.
Stars come in a variety of sizes. The smallest star currently discovered is OGLE-TR-122b. This star is around 96 times more massive than Jupiter. This type of star is called a red dwarf. The largest star discovered so far is called VY Canis Majoris and has a diameter of about 1,975,000,000 kilometres (1.227×109 mi). This star is known as a red hypergiant.
This might be hard to wrap our heads around.
For example, the Earth is about 26,000 miles in circumference. If you were to fly on a commercial jet airliner all the way around the Earth (having to stop to refuel, of course) it would take you about 47 hours. All the while our own Earth (in its own orbit) takes a year to travel around the Sun.
So how long do you think it would take to fly all the way around the circumference of VY Canis Majoris in that same jet airliner?
Well, I saw a video online a couple of years ago that blew my mind. It was about star comparisons and it helped illustrate just how big some of these stars are. If you want to know just how big VY Canis Majoris is and how long it would take you to fly around it in a jet then check out the video. You might be amazed by the answer.
INTERNATIONAL SPACE STATION OVER BATON ROUGE
|Wed Aug 28, 7:58 PM||4 min||77°||36 above NW||11 above SE|
|Thu Aug 29, 8:46 PM||< 1 min||10°||10 above SW||10 above SW|
|Fri Aug 30, 7:57 PM||3 min||20°||19 above WSW||11 above S|
Tonight, Wednesday August 28, the International Space Station, ISS, will cross the Baton Rouge sky at 7:58pm for about 4 minutes. If you have not ever seen the ISS move like a star across the sky it is well worth the effort. Look for a faint object towards the northwest about 36 degrees above the horizon moving towards you. It will move towards the southeast for about 4 minutes and the peak height in the sky will be 77 degrees which is almost over head. As it travels towards you it will get brighter and it will dim as it passes until it fades from sight in the southeast at about 11 degrees above the horizon.
Here is the link to find the ISS anywhere in the world. There is a link in this NASA site to sign up for email or sms text sent to let you know when the ISS will be over your location.
Curiosity Photographs Mars’ Moons
Mars has two moons, Phobos and Deimos. They are very different than our moon in more ways than one. Our Moon orbits Earth at an angle, while Mars’ moons orbit about the planet’s equator. Our Moon is 3474 km across, making it nearly a quarter of Earth’s size. Phobos is about 25 km across, and Deimos is about 10 km across; comparable in size to down town Baton Rouge. Our Moon takes 27 Earth days to orbit one time, Mars’ moons orbit much faster. Phobos, the larger and closer of the two, orbits quickly, circling Mars once every eight hours. Deimos, the smaller and farther of the two, orbits slower, circling once every 30 hours. From the point of view of a person or robot on the surface of Mars, Phobos eclipses Deimos frequently. This is because the two moons orbit in nearly the same plane.
Last week this was photographed for the first time by Curiosity. The spacecraft took a series of images, a sort of timelapse, that scientists here on Earth made into a short movie. Phobos looks vastly larger than Deimos, this is merely because it is closer.
- NASA Rover Gets Movie as a Mars Moon Passes Another (spacefellowship.com)
- NASA’s Curiosity Rover catches images of Mars’ Moons Phobos, Deimos (clarksvilleonline.com)
Spot a Nova in the Sky Tonight!
Alert! A nova has been discovered in the constellation Delphinus the Dolphin and it’s getting brighter each day! Novae visible to human eyes only happen once or twice every ten years. This nova can’t be seen with the naked eye yet, but we think it might be soon.
Two days ago (August 14th) an amateur astronomer named Koichi Itagaki discovered the nova in the constellation Delphinus the Dolphin. Since then, the nova has increased in brightness almost exponentially. Although it isn’t quite visible to the naked eye just yet, it is easily found through binoculars. It is quite possible that its brightness could increase even more in the next few days.
To see the nova, you’ll need a pair of binoculars or a small telescope. Locate the Summer Triangle high over head after sunset. Delphinus is a small parallelogram of stars to the lower left of the triangle. The nova is about two thirds the distance between Delphinus and the edge of the triangle.
What is a nova? The name comes from the Latin word for “new”, because novae seem to be “new stars” that appear in the sky suddenly. This is not actually the case, however. Novae are not to be confused with supernovae. Supernovae are huge explosions that occur when a large star ends its life cycle.
A nova is a sudden increase in brightness in an existing star. One cause of this occurs in a binary system (two stars orbiting each other closely). Sometimes matter will transfer from one star to the other, causing a flareup. Imagine pouring gasoline on a fire.
If you are unable to spot the nova from your backyard, check out the video below from space.com; it shows live footage of the nova taken from the Canary Islands last night.
SUMMER TIME-LAPSE OVER MISSISSIPPI RIVER
This is a time-lapse taken from 10 am through 9pm on August 13 and results in a 10,000 frame video of still pictures with one picture taken every 3 seconds. This video that was originally 5 1/2 minutes long but now squeezed to make this video 1 1/2 minutes.
Shot from the window of my office at LASM.
Photographing Meteors (for beginners!)
Right now, Earth is entering the debris field of comet Swift-Tuttle. What does this mean? Perseid Meteor Shower is upon us! It takes Earth about two weeks to pass through the field of dust, rock, and metal left behind from the comet. These bits, also known as meteors, fall into Earth’s atmosphere and burn up, leaving streaks of light in what appears to be the northern sky. The meteors appear to radiate from the constellation Perseus. It is not essential to know where Perseus is; just look north. In the middle of the two weeks it takes Earth to pass through the debris (this year August 12th and 13th) is the peak of the shower. The best time to see the meteors is after midnight, this year the Moon will be in the Waxing Crescent Phase, and will set in the early evening. Therefore, the sky will be extra dark, making it perfect for photography. The peak is still about a few days away, but that gives you time to practice your meteor photographing skills in anticipation for the big night.
Not all astrophotography is difficult, especially in the age of digital cameras. You can accomplish good results with most digital cameras and a tripod. My two weapons of choice are a Canon 7D with a 180 degree fisheye lens, for capturing pictures that we can use in the planetarium, and of course my Sony Nex-5 (if you’re in the market for a new camera, Sony makes a whole family of Nex cameras at a variety of prices). Small point and shoot cameras can work too! Many of these little cameras come with some if not all of the necessary manual controls.
For the meteor shower I will set up both cameras. Below you can see how the two kinds of pictures look different. The circular “dome master” picture from the 7D projects onto the planetarium dome, while the rectangular picture from the Nex-5 is for printing or viewing on a computer screen.
So here’s what to do. I’d recommend experimenting in your back yard or somewhere with little light from nearby houses first (with long exposure images, you’ll be surprised how much human-made light will show up in your photos). While we hope for totally clear skies, a few stray clouds here and there can make for some interesting additions to your photos. Especially when doing long exposure shots……
1. Point your camera north towards the meteors, and switch it to the manual mode.
2. Higher ISOs make the camera more sensitive to light (better for dark conditions). Some digital cameras let you go to ISOs up in the thousands, but don’t get too carried away. These high ISO values can result in noisy images. I usually set ISO between 800 and 1600 for taking pictures of the night sky.
3. Many digital cameras allow you to adjust your shutter speed. In order to pick up starlight, you need to have a minimum of about 3 seconds of the shutter open. Yes, you read correctly. For everyday photography shutter speeds are hundredths or thousandths of a second. For nighttime shots that shutter needs to stay open for a while to collect as much light as possible. Also, make sure that your f/stop (how wide the aperture is open) is as wide as it can go. The wider the aperture the smaller the f/stop number (f/2 f/4 f/5.6), and the more light enters the lens.
4. Some cameras have a setting called “bulb”, which allows you to leave the shutter open for as long as you want! It closes when you press the picture button again. If you have this setting, experiment with this too. Remember, the Earth is rotating; the stars appear to slowly rise in the east and set in the west. By using the bulb setting and leaving your shutter open for about 10 minutes or so, you will begin to see “star trails” showing up in your picture.
So the longer you leave your shutter open, the longer your “star trails” will become. Also, you will get more meteors in your picture. Check out these cool pictures taken by someone else.
5. So, perhaps we can crank up the ISO and the shutter speed and we’ll get awesome pics, right? Not exactly. Exposure for too long paired with ISO that is too high results in a noisy image. The black parts of your image will have tiny dots of blue, green, and red. This happens when the light sensor in your camera heats up. So there is a trade off…
To capture less light over a longer period of time, try longer exposures of 10 min + , bring the ISO to 800 or less. If you want to capture more light over a short period of time, try higher ISO 800+, bring the shutter speed down under 10 min. If your camera is older, try an ISO threshold of 400 + or -.
6. I will leave you with one last tip. Keep that camera as still as possible! If you don’t have a tripod, you can prop your camera up on a table or even on the ground. When pressing the picture button, be very careful not to knock the camera. If you use the bulb function you will have to press the picture button again to close the shutter and finish the picture. It is most essential that you are careful at this point. Disturbing the camera will blur your image.
In summary. All cameras take slightly different pictures, experiment and see what results you get with your set up. The more you experiment with different settings and combinations the more you will understand how your manual functions work. It’s a learning experience. Have fun!
Happy Anniversary Curiosity!
The Mars rover Curiosity landed on the red planet 1 year ago today close to the time of this post. You can join NASA in the anniversary celebration on NASA TV at 10:45 a.m. EDT (8/6).
During the year Curiosity drove just over one mile. The map shows where Curiosity has been and how far it traveled each day since landing at Bradbury Landing last August 6th. On August 1, 2013 the odometer reading was 1.05 miles at the end of Martian day 351.
4 Days Until Curiosity Celebrates 1st Anniversary on Mars
Next Tuesday is the 1 year anniversary of Curiosity’s landing on Mars. Curiosity will celebrate the day by continuing to drive slowly toward Mt. Sharp. Mt. Sharp is a little over 3 miles high and is in the center of Gale Crater. It began the 5 mile journey to the foot hills of Mt. Sharp on July 7 and should arrive in 9 months to a year. So far Curiosity’s farthest distance traveled in one day was on July 21 when it went 100.3 m.
The distance traveled yesterday was 85.14 m. NASA had hoped it would travel at least 110m per day. Maybe by next Tuesday Curiosity will break another record but with a top speed over flat hard ground of just .09 mph that might be asking a little too much.
- ROVER CAM: Time-Lapse Video Shows Off Curiosity’s First Year on Mars [VIDEO] (designntrend.com)
- News From Mars: Curiosity and Opportunity On the Move (storiesbywilliams.com)