Tag Archives: Voyager 2

IOTA Announcement – Occultation By Neptune’s Moon Triton – 5 October 2017

Greetings, fellow astrophiles!

The following recently came across the ASRAS email list from ASRAS and IOTA member Brad Timerson. If you’ve the gear for it, this is an excellent chance to contribute to some far-out science.

There will be an occultation of a 12.5-mag. star by Neptune’s large satellite Triton the early evening of October 5th (just before 8pm EDT) that will be visible from east of the Appalachian Mountains. It’s the brightest star to be occulted by Triton since the Voyager flyby showed that the satellite has a substantial atmosphere with interesting dark plumes. The occultation will allow us to learn more about the atmosphere, and its variation with altitude and latitude. Sofia plans to fly over the Atlantic, to try to catch the central flash, where Triton’s whole atmosphere will focus/amplify the star’s light, probing deeper parts of the atmosphere. This might also be observed from Florida, but observations anywhere from the East Coast area are sought, to sample a wide range of latitudes of Triton’s atmosphere. Details of the occultation are available at MIT’s Web site for the event at hubble.mit.edu/prediction.html.

The central time for the Rochester area is within several seconds of 7:55:40 pm EDT on October 5th. For an observer near the center of the path, the event could last as long as 3 minutes. Because the Rochester area is north of that path, any occultation or atmospheric dimming would likely last some fraction of that time. You should plan to record the event for about 10 minutes before and after the time shown here.

A main challenge of the event will be to record Triton and the target star with a good signal, preferably with clear separation between 8th-mag. Neptune less than a quarter arc minute away. You will need good scale to separate the objects well enough. More observing tips are given on the MIT web site. The target star is about a magnitude brighter than Triton.

Telescopes as small as 8″ Newtonians will show the target star. (see included image from a European observer) For occultation work, we don’t need to “see” the occulting body (Triton in this case), just the object being occulted. Low light and/or integrating video cameras are best for this observation. However, standard astronomical cameras operated in a mode so as to produce images as quickly as possible will also work. Testing ahead of time to determine the correct exposure to just barely detect Triton should be done. This is to insure that the light from nearby Neptune doesn’t overwhelm that of the nearby moon and star at the time of the event.

Target star, Neptune, and Triton.

I plan on using my 10″ Meade LX200GPS at either f/6.3 (focal reducer) or at the normal f/10 prime focus. I will be using a Watec 120N+ low light video camera and integrating for 64 or 128 frames (2 seconds and 4 seconds). I’m still experimenting and might even need longer integration times.

Triton occults 4UC 410-143659, 5 October 2017 – visible regions from Earth.

Everyone with suitable equipment is encouraged to try this event. And I would appreciate it if this message is forwarded to any nearby universities that might have the ability to observe this event. If individual images are taken (instead of video) the exact time for each exposure is required (don’t depend on the computer’s internal clock. Use a GPS-based time). For analysis, it may be possible to measure the light level on individual images or the images can be combined into a video and measuring software used on the video.

Please contact me (EMAIL) for additional information or to submit observations.

NASA News Two-Fer – Jupiter’s (Smaller) Great Red Spot & A Color-Full Hubble Deep Field

NASA’s Hubble Shows Jupiter’s Great Red Spot is Smaller than Ever Measured

From NASA News: RELEASE: 14-135 – 15 May 2014

Jupiter’s trademark Great Red Spot — a swirling anti-cyclonic storm larger than Earth — has shrunk to its smallest size ever measured.

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According to Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, recent NASA Hubble Space Telescope observations confirm the Great Red Spot now is approximately 10,250 miles across. Astronomers have followed this downsizing since the 1930s. 

Historic observations as far back as the late 1800s gauged the storm to be as large as 25,500 miles on its long axis.  NASA Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured it to be 14,500 miles across. In 1995, a Hubble photo showed the long axis of the spot at an estimated 13,020 miles across. And in a 2009 photo, it was measured at 11,130 miles across.

Beginning in 2012, amateur observations revealed a noticeable increase in the rate at which the spot is shrinking — by 580 miles per year — changing its shape from an oval to a circle.

“In our new observations it is apparent very small eddies are feeding into the storm,” said Simon. “We hypothesized these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot.”

Simon’s team plans to study the motions of the small eddies and the internal dynamics of the storm to determine whether these eddies can feed or sap momentum entering the upwelling vortex, resulting in this yet unexplained shrinkage.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.  Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For images and more information about Hubble, visit www.nasa.gov/hubble

J.D. Harrington
, Headquarters, Washington
, 
j.d.harrington@nasa.gov
Donna Weaver / Ray Villard, 
Space Telescope Science Institute, Baltimore
, 
villard@stsci.edu

Hubble Team Unveils Most Colorful View of Universe Captured by Space Telescope

From NASA News: RELEASE: 14-151 – 3 June 2014

Astronomers using NASA’s Hubble Space Telescope have assembled a comprehensive picture of the evolving universe – among the most colorful deep space images ever captured by the 24-year-old telescope.

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Researchers say the image, in new study called the Ultraviolet Coverage of the Hubble Ultra Deep Field, provides the missing link in star formation. The Hubble Ultra Deep Field 2014 image is a composite of separate exposures taken in 2003 to 2012 with Hubble’s Advanced Camera for Surveys and Wide Field Camera 3.

Astronomers previously studied the Hubble Ultra Deep Field (HUDF) in visible and near-infrared light in a series of images captured from 2003 to 2009. The HUDF shows a small section of space in the southern-hemisphere constellation Fornax. Now, using ultraviolet light, astronomers have combined the full range of colors available to Hubble, stretching all the way from ultraviolet to near-infrared light. The resulting image — made from 841 orbits of telescope viewing time — contains approximately 10,000 galaxies, extending back in time to within a few hundred million years of the big bang.

Prior to the Ultraviolet Coverage of the Hubble Ultra Deep Field study of the universe, astronomers were in a curious position. Missions such as NASA’s Galaxy Evolution Explorer (GALEX) observatory, which operated from 2003 to 2013, provided significant knowledge of star formation in nearby galaxies. Using Hubble’s near-infrared capability, researchers also studied star birth in the most distant galaxies, which appear to us in their most primitive stages due to the significant amount of time required for the light of distant stars to travel into a visible range. But for the period in between, when most of the stars in the universe were born — a distance extending from about 5 to 10 billion light-years — they did not have enough data.

“The lack of information from ultraviolet light made studying galaxies in the HUDF like trying to understand the history of families without knowing about the grade-school children,” said principal investigator Harry Teplitz of Caltech in Pasadena, California. “The addition of the ultraviolet fills in this missing range.”

Ultraviolet light comes from the hottest, largest and youngest stars. By observing at these wavelengths, researchers get a direct look at which galaxies are forming stars and where the stars are forming within those galaxies.

Studying the ultraviolet images of galaxies in this intermediate time period enables astronomers to understand how galaxies grew in size by forming small collections of very hot stars. Because Earth’s atmosphere filters most ultraviolet light, this work can only be accomplished with a space-based telescope.

“Ultraviolet surveys like this one using the unique capability of Hubble are incredibly important in planning for NASA’s James Webb Space Telescope,” said team member Dr. Rogier Windhorst of Arizona State University in Tempe. “Hubble provides an invaluable ultraviolet light dataset that researchers will need to combine with infrared data from Webb. This is the first really deep ultraviolet image to show the power of that combination.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For Hubble Ultra Deep Field 2014 images and more information about Hubble, visit hubblesite.org/news/2014/27 and www.nasa.gov/hubble

J.D. Harrington
, Headquarters, Washington
, 
j.d.harrington@nasa.gov
Ann Jenkins / Ray Villard, 
Space Telescope Science Institute, Baltimore
, 
jenkins@stsci.edu / villard@stsci.edu

NASA Space Place – The Most Volcanically Active Place Is Out-Of-This-World!

Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing. Your tax dollars help promote science! The following article was provided for reprinting in November, 2013.

By Dr. Ethan Siegel

2013february2_spaceplaceVolcanoes are some of the most powerful and destructive natural phenomena, yet they’re a vital part of shaping the planetary landscape of worlds small and large. Here on Earth, the largest of the rocky bodies in our Solar System, there’s a tremendous source of heat coming from our planet’s interior, from a mix of gravitational contraction and heavy, radioactive elements decaying. Our planet consistently outputs a tremendous amount of energy from this process, nearly three times the global power production from all sources of fuel. Because the surface-area-to-mass ratio of our planet (like all large rocky worlds) is small, that energy has a hard time escaping, building-up and releasing sporadically in catastrophic events: volcanoes and earthquakes!

Yet volcanoes occur on worlds that you might never expect, like the tiny moon Io, orbiting Jupiter. With just 1.5% the mass of Earth despite being more than one quarter of the Earth’s diameter, Io seems like an unlikely candidate for volcanoes, as 4.5 billion years is more than enough time for it to have cooled and become stable. Yet Io is anything but stable, as an abundance of volcanic eruptions were predicted before we ever got a chance to view it up close. When the Voyager 1 spacecraft visited, it found no impact craters on Io, but instead hundreds of volcanic calderas, including actual eruptions with plumes 300 kilometers high! Subsequently, Voyager 2, Galileo, and a myriad of telescope observations found that these eruptions change rapidly on Io’s surface.

Where does the energy for all this come from? From the combined tidal forces exerted by Jupiter and the outer Jovian moons. On Earth, the gravity from the Sun and Moon causes the ocean tides to raise-and-lower by one-to-two meters, on average, far too small to cause any heating. Io has no oceans, yet the tidal forces acting on it cause the world itself to stretch and bend by an astonishing 100 meters at a time! This causes not only cracking and fissures, but also heats up the interior of the planet, the same way that rapidly bending a piece of metal back-and-forth causes it to heat up internally. When a path to the surface opens up, that internal heat escapes through quiescent lava flows and catastrophic volcanic eruptions! The hottest spots on Io’s surface reach 1,200 °C (2,000 °F); compared to the average surface temperature of 110 Kelvin (-163 °C / -261 °F), Io is home to the most extreme temperature differences from location-to-location outside of the Sun.

Just by orbiting where it does, Io gets distorted, heats up, and erupts, making it the most volcanically active world in the entire Solar System! Other moons around gas giants have spectacular eruptions, too (like Enceladus around Saturn), but no world has its surface shaped by volcanic activity quite like Jupiter’s innermost moon, Io!

Learn more about Galileo’s mission to Jupiter: solarsystem.nasa.gov/galileo/.

Kids can explore the many volcanoes of our solar system using the Space Place’s Space Volcano Explorer: spaceplace.nasa.gov/volcanoes/.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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Caption: Io. Image credit: NASA / JPL-Caltech, via the Galileo spacecraft.

About NASA Space Place

The goal of the NASA Space Place is “to inform, inspire, and involve children in the excitement of science, technology, and space exploration.” More information is available at their website: http://spaceplace.nasa.gov/