Curiosity Photographs Mars’ Moons

Phobos has a large crater known as Stickney.

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Deimos is slightly smaller than Phobos.

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.

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. delphinus

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.

Photographing Meteors (for beginners!)

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Debris left behind by comet Swift-Tuttle intersects Earth’s orbit. This year, Earth travels through the densest part of the debris field around August 12.

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.

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Canon 7D (left) and Sony Nex-5 (right).

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.

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Canon 7D + Tripod + ISO 1600 + Shutter Open for 65 Seconds. Death Valley has America’s darkest night skies, but with these settings we picked up the lights of Las Vegas over 100 miles away. Click the pic to see the full size version.

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.

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Nex-5 + Tripod + ISO 1600 + shutter open for 80 seconds. This photo was taken later at night, the Milky Way was in the Western sky (pointing away from Las Vegas Lights).

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.

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Click the picture to visit this photographer’s page with more meteor shower pictures.

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 195th Birthday, Maria Mitchell!

mariamitchellMaria Mitchell is considered the first professional female astronomer in America, and is a special inspiration for me. She was the first professor of Astronomy at my Alma Mater, Vassar College. Among the first nine professors hired shortly after Vassar’s founding, Mitchell was the only female professor at the time. Maria Mitchell paved the way for other female scientists throughout the 1800s.

Prior to being hired at Vassar, Mitchell had a solid astronomy career under her belt. In 1847 she was awarded a medal by the King of Denmark for her discovery of a comet. In 1848 Mitchell became the first woman elected into membership of the American Academy of Arts and Sciences. Then, in 1850, she was inducted into the American Association for the Advancement of Science.

The Maria Mitchell Observatory

Vassar College was founded by Matthew Vassar in 1865 as an institution that offered young women an education equal to that of the prominent men’s colleges of the day. Vassar was and is not only an educational institution but a cultural one as well. Mitchell served as a unique inspiration to her female students. Not only did she teach science, but she lead many discussions about women’s rights. Mitchell challenged the college to raise her salary to match that of her male colleagues, a battle she eventually won. Mitchell encouraged her students to be self sufficient by paying part of their tuition through work study, something unheard of for women at the time.

Mitchell lived in the college observatory for over 20 years. Her students, who lived nearby in Main Building, would wake late in the night to attend classes at the observatory. This brings back memories of the late night treks from Main Building to and from the observatory during my years at Vassar.

Vassar’s new observatory, where the dome poems are now read.

Maria Mitchell viewed the observatory as not only a space for study, but also as a space for gathering and fellowship. She began the “dome party” where students would present astronomy poetry in the observatory each year, a tradition that is still alive and well at Vassar today. Astronomy students still gather at the end of each school year at the new observatory to recite poems they have written (both serious and humorous) about astronomy, classes, and working at the observatory.

Before his death, Matthew Vassar said to the college Board of Trustees of Maria Mitchell, “Let the foremost woman of our land be among the most advanced and honored pilots and guardians of coming women, and I cheerfully leave my name to be associated with the result.” And it is still so to this day.

Earth’s Group Photo

Staff at JPL celebrate Earth’s snapshot.

Last week, people all across the world waved at the skies in a group celebration of Earth’s portrait shot from 898,000,000 miles away. The Cassini spacecraft has been orbiting Saturn for nearly a decade, and in fact most of the dazzling images you’ve seen of Saturn, its rings, and its moons were captured by Cassini. On Friday, July 19, 2013 Cassini’s cameras captured images of Earth, the Moon, and Saturn in the same image frame. This wasn’t the first time Earth’s picture was taken from the outer Solar System, but this time the event was made known to the public in advance of its happening. “Wave at Saturn” images flooded social media sites as waving people took pictures with hula hoops to show their excitement and support.

Artist’s conception of Cassini orbiting Saturn.

Today we saw the first images released of Saturn and Earth. It has taken several days for the images to be ready. Why is this?

Have you ever tried to take a picture in the dark? It’s difficult… You need to keep your camera still, and leave your shutter open for a long time to capture more light. The same idea applies here. Earth was 898 million miles away from Cassini when these pictures were taken, showing up as only a faint blue dot. To add to the challenge, bright and shiny Saturn sits in the foreground of the image. On top of this, Cassini is in motion as it orbits Saturn.  Imagine trying to take a picture of a car with its headlights on and a tiny firefly sitting in a tree behind it, while riding a bicycle past the scene….

Cassini accomplishes this by taking hundreds of images. These images were sent back to humans on Earth for processing. For the past several days, scientists at NASA have been combining these images together with special computer software. To put it simply, the images are layered on top of each other and combined to form a single image.

The finished product of Cassini’s Earth, Moon, and Saturn portrait is not yet complete. The image released today is one of 33 “tiles” of the final mosaic that will show the entire planet Saturn, its rings, and Earth. Creating this picture takes a lot of work. Stay tuned as more of the puzzle is pieced together…

The first image released by NASA of Earth, Moon, and Saturn’s group photo. Earth is marked by an arrow. The moon is barely visible as a faint smudge to the lower right. This image alone was created by combining over 200 individual images captured by Cassini.

Pluto’s New Moons Have Names!

This week the International Astronomical Union (made famous in the eyes of the public for reclassifying Pluto as a Dwarf Planet) gave Pluto’s newly discovered moons their official names. Previously known as “P4” and “P5”, these tiny moons are now named Kerberos and Styx respectively. The names were the result of an online naming contest where people could suggest and vote on their favorite names. You  may have seen news a few months ago that one of the moons was named Vulcan (after the Roman god of fire, but also the native world of Dr. Spock from Star Trek). Vulcan won the naming contest, but in the end the official decision was up to the IAU. Here at the planetarium we were a little bummed about the decision to cast out the vote for Vulcan as a name..

Anyways…

The IAU wanted to keep with the Pluto/Underworld theme and Vulcan just didn’t fit in with that! Pluto was the Roman god of the Underworld and it’s largest moon was named Charon, after the ferryman who transported souls across the river Styx. In 2005 two more moons were discovered. They were named Nix and Hydra. Nix (originally spelled Nyx) was the mother of Charon, and Hydra was a many-headed serpent that guarded the underworld. Kerberos (spelled this way to distinguish it from the asteroid already named Cerberus) was the three headed dog that guarded the mythical entrance to the underworld. Styx of course is the mythical river that souls must cross in order to enter into the underworld.

The new moons are very small (Styx is barely visible in this Hubble image). These moons aren’t much bigger than downtown Baton Rouge!

New Show: Dynamic Earth

Coming July 2, 2013!

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Get excited, our new lineup of planetarium shows begins this Tuesday!

Explore the inner workings of Earth’s climate system. With visualizations based on satellite monitoring data and advanced supercomputer simulations, this cutting-edge production follows a trail of energy that flows from the Sun into the interlocking systems that shape our climate: the atmosphere, oceans, and the biosphere. Audiences will ride along on swirling ocean and wind currents, dive into the heart of a monster hurricane, come face-to-face with sharks and gigantic whales, and fly into roiling volcanoes.

The Reason for the Season

Happy summer! Today is the Summer Solstice, our hemisphere’s longest day. Our Earth has seasons because its axis is tipped about 23 degrees, in other words it isn’t straight up and down. As the Earth orbits the Sun, the tilt causes us to experience seasons. In the United States, we have summer when the northern hemisphere is tilting towards the Sun. The summer solstice itself is the day when the axis is tilted most towards the Sun. From the ground, we can see that the Sun takes the highest path across the sky, and we experience the year’s longest day and shortest night. As the Earth continues in its orbit, the axis will slowly tilt away from the Sun. Little by little, we will see the Sun take a lower path across the sky and the days get shorter. Once the Earth has reached the opposite side of the Sun, its axis is tilted away and we experience winter. What’s happening in the Southern hemisphere during all of this? Exactly the opposite! They are having their Winter Solstice today.

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30 Year Anniversary of First American Woman in Space

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30 Years ago on June 18, 1983, Sally Ride flew into space aboard the Challenger mission STS-7. She was the first American woman to travel to space. She paved the way for 44 more American women who have so far become astronauts, in addition to countless more in the future. This year in 2013, four out of the eight astronauts are women. Sally Ride passed away last July, but she remains an inspiration to women in science.

Mission patch for the STS-7 mission.

Mission patch for the STS-7 mission.