Tag Archives: Cassini Spacecraft

NASA Space Place – Snowy Worlds Beyond Earth

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 December, 2017.

The Space Place article format has changed recently, including more embedded images. To simplify the posting process, a PDF version of the article is provided below, with a snippet of the article reproduced below it.

Download as PDF: Snowy Worlds Beyond Earth

By Linda Hermans-Killiam

2013february2_spaceplace

There are many places on Earth where it snows, but did you know it snows on other worlds, too? Here are just a few of the places where you might find snow beyond Earth:

A Moon of Saturn: Enceladus

Saturn’s moon, Enceladus, has geysers that shoot water vapor out into space. There it freezes and falls back to the surface as snow. Some of the ice also escapes Enceladus to become part of Saturn’s rings. The water vapor comes from a heated ocean which lies beneath the moon’s icy surface. (Jupiter’s moon Europa is also an icy world with a liquid ocean below the frozen surface.) All of this ice and snow make Enceladus one of the brightest objects in our solar system.

Caption: Enceladus as viewed from NASA’s Cassini spacecraft. Credit: NASA

Want to learn more about weather on other planets? Check out NASA Space Place: spaceplace.nasa.gov/planet-weather

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

About NASA Space Place

With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov (facebook|twitter) to explore space and Earth science!

Free Astronomy Magazine – November-December 2017 Issue Available For Reading And Download

Greetings, fellow astrophiles!

The most recent issue of Free Astronomy Magazine (November-December, 2017) is available for your reading and downloading pleasure at www.astropublishing.com (click the link to go directly to the issue).

Free Astronomy Magazine was featured as the first of a series of articles on great free online content for amateur astronomers (see A Universe Of Free Resources Part 1) and we’ll be keeping track of future publications under the Online Resources category on the CNYO website.

You can find previous Free Astronomy Magazine issues by checking out our Free Astronomy Magazine Category (or look under the Education link in our menu).

For those wanting a quick look at what the issue has to offer, the Table of Contents is reproduced below.

November-December 2017

The web browser-readable version of the issue can be found here:

November-December 2017 – www.astropublishing.com/6FAM2017/

For those who want to jump right to the PDF download (27 MB), Click here: November-December 2017

NASA Space Place – The Shape Of The Solar System

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 June, 2017.

By Marcus Woo

2013february2_spaceplaceWhen Stamatios (Tom) Krimigis was selected for the Voyager mission in 1971, he became the team’s youngest principal investigator of an instrument, responsible for the Low Energy Charged Particles (LECP) instrument. It would measure the ions coursing around and between the planets, as well as those beyond. Little did he know, though, that more than 40 years later, both Voyager 1 and 2 still would be speeding through space, continuing to literally reshape our view of the solar system.

The solar system is enclosed in a vast bubble, carved out by the solar wind blowing against the gas of the interstellar medium. For more than half a century, scientists thought that as the sun moved through the galaxy, the interstellar medium would push back on the heliosphere, elongating the bubble and giving it a pointy, comet-like tail similar to the magnetospheres—bubbles formed by magnetic fields—surrounding Earth and most of the other planets

“We in the heliophysics community have lived with this picture for 55 years,” said Krimigis, of The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. “And we did that because we didn’t have any data. It was all theory.”

But now, he and his colleagues have the data. New measurements from Voyager and the Cassini spacecraft suggest that the bubble isn’t pointy after all. It’s spherical.

Their analysis relies on measuring high-speed particles from the heliosphere boundary. There, the heated ions from the solar wind can strike neutral atoms coming from the interstellar medium and snatch away an electron. Those ions become neutral atoms, and ricochet back toward the sun and the planets, uninhibited by the interplanetary magnetic field.

Voyager is now at the edge of the heliosphere, where its LECP instrument can detect those solar-wind ions. The researchers found that the number of measured ions rise and fall with increased and decreased solar activity, matching the 11-year solar cycle, showing that the particles are indeed originating from the sun.

Meanwhile, Cassini, which launched 20 years after Voyager in 1997, has been measuring those neutral atoms bouncing back, using another instrument led by Krimigis, the Magnetosphere Imaging Instrument (MIMI). Between 2003 and 2014, the number of measured atoms soared and dropped in the same way as the ions, revealing that the latter begat the former. The neutral atoms must therefore come from the edge of the heliosphere.

If the heliosphere were comet-shaped, atoms from the tail would take longer to arrive at MIMI than those from the head. But the measurements from MIMI, which can detect incoming atoms from all directions, were the same everywhere. This suggests the distance to the heliosphere is the same every which way. The heliosphere, then, must be round, upending most scientists’ prior assumptions.

It’s a discovery more than four decades in the making. As Cassini ends its mission this year, the Voyager spacecraft will continue blazing through interstellar space, their remarkable longevity having been essential for revealing the heliosphere’s shape.

“Without them,” Krimigis says, “we wouldn’t be able to do any of this.”

To teach kids about the Voyager mission, visit the NASA Space Place: spaceplace.nasa.gov/voyager-to-planets

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

Caption: New data from NASA’s Cassini and Voyager show that the heliosphere — the bubble of the sun’s magnetic influence that surrounds the solar system — may be much more compact and rounded than previously thought. The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue. Image credits: Dialynas, et al. (left); NASA (right)

About NASA Space Place

With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov (facebook|twitter) to explore space and Earth science!