Uncategorized – Page 16 – Watch the Skies

Fireball in the Sky!

It was brief, but it was brilliant! On Saturday, Oct. 2, 2010 at approximately 8:50 p.m. CDT, cameras operated by NASA’s Meteoroid Environment Office at Marshall Space Flight Center in Huntsville, Ala., recorded a slow moving fireball moving from the north to the southwest.

Enhanced-color image of Alabama fireball meteor.

The fireball was moving approximately 35,300 mph (15.8 km/s). It appeared at an altitude of 45.5 miles (73.2 km) and ablated, or burned up, at an altitude of 25.3 miles (40.7 km). The meteor experienced significant deceleration as it entered the atmosphere, resulting in a meteor trail that lasted about three seconds, seen in the movie below:

Using data from cameras at both Huntsville and Chickamauga, Ga., astronomers at the Marshall Center determined that the meteor was located over Marion County, Ala.

Diagram of fireball’s path over Marion County, Ala.

Images and video courtesy of Danielle Moser, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.

Here Comes Comet Hartley 2!

A pale green interloper among the stars of Cassiopeia, Comet Hartley 2 shines in this four-minute exposure taken on the night of Sept. 28, 2010, by NASA astronomer Bill Cooke:

Still too faint to be seen with the unaided eye, the comet was 18 million miles away from Earth at the time. Cooke took this image using a telescope located near Mayhill, N.M., which he controlled via the Internet from his home computer in Huntsville, Ala.

Comet-watching from the comfort of your living room! Modern astronomy is truly amazing…

More About Comet 103P/Hartley 2

Comet 103P/Hartley 2, a small periodic comet, was discovered in 1986 by Malcolm Hartley, an Australian astronomer. It orbits the sun about every 6.5 years, and on Oct. 20, the comet will make its closest approach to Earth since its discovery. In this case, “close” means 11 million miles, or 17.7 million kilometers. A moonless sky will make for promising viewing conditions in the northeastern skies, especially just before dawn.

Comet Hartley 2’s nuclear diameter is estimated at 0.75-0.99 of one mile — 1.2-1.6 kilometers — and it’s believed to have enough mass to make approximately 100 more apparitions, or appearances, near Earth. The 2010 appearance also marks one of the closest approaches of any comet in the last few centuries.

Images courtesy of Bill Cooke, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.

Bright September Meteor

Marshall Space Flight Center PAO Steve Roy was out jogging early Friday morning with his dogs, Lilly and Scout, when he couldn’t help but notice this bright meteor low in the eastern sky.

Also seen by NASA’s all sky meteor cameras at MSFC and in Chickamauga, GA, the meteor was located above the Atlanta area, some 180 miles away from where he was running.

Moving at 97,500 miles per hour, it disintegrated in a flash of light 45 miles above the ground. You can watch the meteor as captured by the cameras at the Marshall Space Flight Center:
https://www.nasa.gov/multimedia/videogallery/index.html?media_id=18616453

and also as seen by the camera at Chickamauga:
https://www.nasa.gov/multimedia/videogallery/index.html?media_id =18616422.

Images/movies courtesy of Bill Cooke, NASA’s Meteoroid Environment Office, Marshall Space Flight Center, Huntsville, Ala.

When to look? In what direction?

Lots of questions coming in, so I thought I would deal with them here.

I live in xxx… Can I see Perseids?

Check out the map below. Unless you live in the red shaded area, you will be able to see the shower. EVERYONE in the United States and Europe with clear weather will be able to see it, provided they are away from city lights and have clear, dark skies. Most other parts of the world will be able to see the shower as well.

When do I look?

You should start to see Perseids around 10 PM local time. The rate will increase throughout the night until just before dawn (3 to 4 am), when you may be able to see as many as 80-100 per hour. Be sure to allow about 45 minutes to allow your eyes to dark adapt.

Where do I look?

Lie on your back on a sleeping bag, blanket, or lawn chair and look straight up and take in as much sky as possible. Do not look at the constellation Perseus, where is the shower radiant is located, as you will see fewer meteors. This is because the length of the meteor gets longer the farther it appears from the radiant; to see nice bright meteors, you need to look some distance away from Perseus, which for U.S. observers is off to the northeast. Looking straight up, towards the Zenith, is a good choice and enables you to take in a lot of sky.

Do not use binoculars or a telescope, as they have narrow fields of view and will greatly reduce your chances of seeing meteors.

Hope this helps and wish everyone lots of meteors!

Will the Perseid shower be visible from {insert your location}?

I am asked this question over and over again, and it’s a good one. Everyone knows that you have to be in the right place to observe solar eclipses and other astronomical goings-on, so why should meteor showers be any different?

You do have to be in the right part of the planet to view meteor outbursts or storms, because the trails of comet debris are so narrow (hundreds of thousands of miles) that it only takes a few hours for the Earth to pass through the stream. A few hours is not enough time for the Earth to do a complete rotation (which takes 24 hours), so only those people located in areas where it is night and where the radiant is visible will be able to see the outburst or storm. These dramatic events require the viewers to be in the right ranges of both latitude AND longitude.

This is not true for normal meteor showers, like this year’s Perseids. The main stream of particles extends for millions of miles along Earth’s orbit, requiring days for it to cross. All we need is one day to take the longitude out of the visibility calculations, because then the entire planet will experience night while the shower is still going on. That’s the good news.

The kicker is that we not only have to have darkness, but also the radiant — in this case, located in the constellation of Perseus — has to be visible, i.e. above the horizon. The elevation of the radiant depends in part on latitude of the observer, and one can derive — or look up, in this age of Google — a relatively simple equation that gives the maximum elevation of the radiant:

maximum elevation = 90 – |dec -lat|

where dec is the declination of the radiant and lat is latitude of the observer (all in degrees). The vertical lines before dec and after lat mean to take the absolute value of dec — lat. In order to see meteors from the shower, the maximum elevation must be 0 or greater (preferably more than 15 degrees). In the case of the Perseids, dec = 58 deg, so it is easy to calculate the maximum elevation for various latitudes:

We see that everyone in the northern hemisphere has a shot at seeing Perseids (weather permitting), but folks south of -32 degrees latitude get the shaft.

On the world map above, the red shaded area is the region where the Perseids will not be visible. If you live south of Brazil, at the very southern tip of Africa, or southern Austrailia, you need to take a road trip to the North if you wish to see Perseids. If you want see decent numbers, it will be a long ride, as you need to trek to somewhere above -17 degrees latitude.

So will I see Perseids? You can find out on your own — look up your latitude (remember, Google is your friend), use the equation above, stick in 58 degrees for the dec, and calculate the maximum elevation. If it is above 15 degrees, you are good.

Remember to get away from city lights. A dark sky is important.

Enjoy the show!

How low can they go?

Real-life meteor showers are not like what you see in movies — there are no flaming rocks barreling out of the sky blasting holes in buildings, or sending cars hurling many yards through the air. Most meteor showers are caused by debris left behind by comets, icy particles mixed with dust and organics that stand no chance of surviving their kamikaze death dives through Earth’s atmosphere. The meteors that actually do make it through, becoming meteorites when they strike ground, are very, very few in number and originate from asteroids (and much more rarely, Mars and the Moon). There are only a handful of recorded falls each year.

So how low can a Perseid get? The NASA all-sky cameras can provide the answer, at least for the bigger Perseids (inch or so across); the smaller particles burn up higher. Our two station camera network can determine the trajectory of a meteor through triangulation, and tell us the start height of the meteor (the location where it is first seen) and its end height (the location where it disappears or “burns up”). Both cameras observed 80 Perseids last year and 24 so far this year, which gives us enough data to tackle the problem.

We start out by taking the end heights of the Perseids and throwing them into 1 mile wide altitude bins. This results in the following graph:

Looking at the plot, it is apparent that most large Perseids burn up at about 56 miles (90 km) altitude. Some ablate as high as 65 miles (104 km), whereas others may get as low as 47 miles (76 km) altitude. We see none getting down to 45 miles or lower, which gives this old ground dweller a warm fuzzy feeling — I can enjoy the shower, secure in the knowledge that the meteors are going poof way up there.

It turns out that our friends the Perseids don’t get very low at all, ending their interplanetary journeys at least 46 miles above our heads.

LCROSS Hits Its Mark!

Onlookers participate in LCROSS pre-impact activities at NASA’s Ames
Research Center. Credit: NASA

The crowd at NASA Ames was poised and ready for impact as the LCROSS camera started sending back stunning images of the moon’s south pole. At impact, a flash or large plume wasn’t visible with the LCROSS camera, but even though we didn’t see it doesn’t mean it wasn’t there.

The LCROSS mission operations team initiated power-up of the LCROSS science
payload and captured this image of the moon. Credit: NASA

Mission scientists confirmed the LCROSS spacecraft monitored whatever the Centaur rocket lifted from the crater floor. At this time, it isn’t yet clear how much dust was raised but LCROSS Principal Investigator Tony Colaprete did confirm that the instruments onboard the sheparding spacecraft captured the Centaur impact crater.

Now mission scientists need more time to study the data. In the next few weeks, scientists will pore over the information to determine if water ice does exist in the Cabeus crater.

To stay up to date, be sure to follow the LCROSS website, the LCROSS twitter feed, and its Facebook page.

https://www.nasa.gov/mission_pages/LCROSS/main/index.html

Impact from the Lunar Reconnaissance Orbiter's Line of Sight

Scientist and engineers are adjusting LRO’s orbit to have it fly its closest approach to the Cabeus target site just 90 seconds after the Centaur impacts the lunar surface.

Artist Concept of the Lunar Reconnaissance Orbiter with Apollo mission
imagery in the background. Credit: NASA

The Lunar Reconnaissance Orbiter, better known as LRO, was a sister payload to LCROSS during launch and now the orbiter will pass over the moon at just the right time to capture the Centaur impact to collect key data about the physics of the impact and how volatile materials may have been mobilized.

This image shows the moon’s south pole, as seen by the 1994 Clementine
mission. The possibility of frozen water is one of many reasons NASA is
interested in thisspot as a potential future landing site. However, many of the
craters in this area where frozen water sources are most likely to be found are
in constant shadow, which inhibited Clementine’s ability to see into these craters.
These shadows are the very dark areas at the pole’s center. The upcoming
Lunar Reconnaissance Orbiter mission will study this area and search for
evidence of frozen water sources. Credit: NASA

During and after impact LRO’s LAMP far UV spectrometer will search for evidence of significant water ice or water signatures and how they evolve in the moon’s atmosphere. LRO’s Diviner radiometer will peer into the impact site to measure the heating effects caused by impact and how the temperature changes over time. LRO will continue to study the impact site using its suite of instruments long after the dust settles.

A Personal Perspective
David A. Paige, principal investigator Diviner
Diviner is one of the seven instruments aboard LRO

We on the LRO Diviner team are looking forward to the LCROSS impact with great anticipation. It’s not every day that we will have an opportunity to excavate a significant volume of material from one of the moon’s permanently shadowed polar cold traps. We expect that a new lunar impact crater will form, and that dust, rock, and possibly cold-trapped volatile materials such as water ice will be thrown into space.

Everything we learn about the LCROSS impact will come from Earth observations and from observations from nearby spacecraft. Diviner will get excellent views of the impact site as LRO flies by. We intend to make maps of the radiometric temperature of the impact site before and after the impact, as well as observations of the dust plume that will be lofted during the impact event. Diviner’s observations may help confirm the location of the LCROSS impact, and its effects on the impact on the surrounding terrain. Diviner has already mapped the impact site on previous orbits and so any changes that are detected will be of great interest. We have no idea what LCROSS will uncover, but we’re anxious to know the results.

Diviner has acquired the first global daytime and nighttime thermal
maps of the moon. These maps were assembled using Diviner data obtained during
August and the first half of September, 2009. Credit: NASA/GSFC/UCLA

Hopefully, everything will go well for LCROSS and LRO on Friday morning and we’ll learn something new and exciting about the moon!

A New Look at an Old Neighbor

We have yet to uncover the full wealth of scientific information the moon holds. It at the cornerstone of understanding the birth and evolution of Earth and other planets, therefore we need to explore it.

The moon looks very unchanging and calm in the night sky and is rarely thought of as an active planetary body. What most people don’t know, is the moon receives LCROSS-sized impacts about once a week — that’s more than 50 impacts a year! It also is interesting to note that it experiences thousands of “moonquakes” each year and releases energy by heat flow, electromagnetic conduction and tides from Earth and the Sun.

Moon’s Copernicus Crater — Lunar Orbiter Photo 1966 (Credit: NASA)

LCROSS is unique compared to the natural barrage of material impacting the moon because it’s designed to know exactly where and when it will impact — the Cabeus crater near the moon’s south pole.

Craters of interest around the lunar south pole. LCROSS is targeting Cabeus A.
(Credit: NMSU/MSFC Tortugas Observatory)

Little is known about the moon’s permanently shadowed regions and we may find some unexpected results from this unique mission. The crater is more than two miles deep and may be one of the coldest places in the solar system. Scientists believe it has been void of sunlight for billions of years and represents an optimal location for determining if water ice exists on the moon.

Teams of scientists, engineers and astronomers across NASA, industry and academia are working tirelessly to advance space exploration and knowledge of our solar system with this mission. Now that LCROSS is two days away from impact, they still have a lot of work ahead of them. For example, they will observe the impacts, gather images of them, measure the quantity of water and identify its form and study the lunar soil.

This exciting mission promotes participatory exploration from the professional and amateur astronomy community, students and the general public.

During impact, at least twenty-five Earth-based observatories will be aimed at the Cabeus crater to witness the moment the lunar dust rises and is suspended in the sunlight to determine if it contains water vapor.

It's Almost Time!

It’s almost time!

It’s been over three months since the Atlas V soared from Cape Canaveral, Fla. into space carrying the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (“LCROSS” for short). Now it’s finally time for LCROSS to do its things and get up close and personal with the moon.

An artist’s interpretation of NASA’s LCROSS spacecraft observing the first
impact of its rocket booster’s Centaur upper stage before heading in for its
own crash into the moon’s south pole. Credit: NASA

On Oct. 9 beginning at 6:30 a.m. CDT, the LCROSS spacecraft and heavier Centaur upper stage rocket will execute a series of procedures to separately hurl themselves toward the lunar surface to create a pair of debris plumes that will be analyzed for the presence of water ice. The Centaur is aiming for the Cabeus crater near the moon’s south pole and scientist expect it to kick up approximately ten kilometers (6.2 miles) of lunar dirt from the crater’s floor.

Image of NASA’s Infrared Telescope Facility. Credit: NASA

The sun never rises above certain crater rims at the lunar pole and some crater floors may not have seen sunlight for billions of years. With temperature estimated to be near minus 328 degrees Fahrenheit, these craters can ‘cold trap’ or capture most volatiles or water ice.

Earth-based radar image of the North Pole of the Moon, showing the position of the crater
Erlanger (arrow). Photo: Arecibo Observatory and NASA

On the day of impact, LCROSS at approximately 40,000 kilometers (25,000 miles) above the lunar surface will spin 180 degrees to turn its science payload toward the moon and fire thrusters to slow down. The spacecraft will observe the flash from the Centaur’s impact and fly through the debris plume. Data will be collected and streamed to LCROSS mission operations for analysis. Four minutes later, LCROSS also will impact, creating a second debris plume.

The LCROSS science team will lead a coordinated observation campaign that includes LRO, the Hubble Space Telescope, observatories on Hawaii’s Mauna Kea and amateur astronomers around the world.

It’s an exciting time for the most prominent object in our night sky with water being found on the surface last week by NASA’s Moon Mineralogy Mapper — one of eleven scientific devices carried by the Chandrayaan-One spacecraft of the Indian Space Research Organization.

These images show a very young lunar crater on the side of the moon that faces away
from Earth, as viewed by NASA’s Moon Mineralogy Mapper on the Indian Space
Research Organization’s Chandrayaan-1 spacecraft. Image credit: NASA

However, the Moon Mineralogy Mapper can only observe lunar soil to a depth of a few millimeters and the amount of water present in that layer is very small. It’s been said the driest deserts on Earth have more water than the surface of the moon near its poles. LCROSS could prove that water does exist deeper beneath the moon’s surface and present a valuable resource in the human quest to explore the solar system.

Astronaut James Irwin, lunar module pilot, gives a military salute while standing
beside the deployed U.S. flag during the Apollo 15 lunar surface extravehicular
activity (EVA) at the Hadley-Apennine landing site. Credit: NASA

Two ways to watch the impact:

Tune into NASA TV. The Agency will broadcast impact live from the moon, with coverage beginning Friday morning at 5:15 a.m. CDT. The first hour, pre-impact, will offer expert commentary, spacecraft status reports, and a computer-generated preview of the impacts.

Or you can watch in your backyard using your telescope. Viewing opportunities are best for the Pacific Ocean and western parts of North America due to absence of light and a good view of the Moon at the time of impact. Hawaii is the best place to be, with Pacific coast states of the USA a close second. Any place west of the Mississippi River, however, is a potential observing site.

W.M. Keck Observatory and the NASA Infrared Telescope Facility with Haleakala on
Maui in the distance as seen at sunset from Mauna Kea. Credit: John Fischer