A sungrazing comet is a comet that passes extremely close to the Sun at perihelion — sometimes within a few thousand kilometers of the Sun’s surface. While small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong evaporation and tidal forces they experience often lead to their fragmentation.

What can these comets tell us about our solar system? Perhaps they can even reveal some of the mysteries of the sun itself…

From NASA’s Scientific Visualization Studio. Analysis of the meteor that flew in over Russia tells a surprising tale. Shortly after dawn on Feb. 15, 2013, a bolide measuring 18 meters across and weighing 11,000 metric tons, screamed into Earth’s atmosphere at 18.6 kilometers per second. Burning from the friction with Earth’s thin air, the space rock exploded 23.3 kilometers above Chelyabinsk, Russia.

The event led to the formation of a new dust belt in Earth’s stratosphere. Scientists used data from the NASA-NOAA Suomi NPP satellite along with the GEOS-5 computational atmospheric model to achieve the first space-based observation the long-term evolution of a bolide plume.

From NASA’s Scientific Visualization Studio. In only five short years, the FERMI Space Telescope has observed and catalogued an astounding amount of phenomena, including some of the most high-energy events in our galaxy.

The Fermi Gamma-ray Space Telescope (FGST), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma-ray bursts.

Take a look at the recent changes that are taking place at Earth’s North and South Pole. Tom Wagner, the Cryosphere program manager at NASA, takes a look at the loss of Artic Sea Ice, changes in Greenland and Antarctica, and reveals some surprisingly blatant truths about what is happening to our planet.

One of the greatest scientific endeavors ever launched. Hubble sees back to the early days of the universe. Revel in this big picture look at what Hubble does, adapted from Hubblecast, with the incomparable Dr. J.

A new type of exoplanet finder comes on line in the next year. Working with the giant telescopes of the Chilean outback, the Very Large Telescope on Mt Paranal, it will distinguish the polarized light of planet atmospheres from the light of their parent stars. This new planet detection system offers an ingenious new way to tease out the light of a planet with the overwhelming brightness of a star. Adapted from EsoCast, with Dr. J.

This is a preview of our upcoming episode of COSMIC JOURNEYS. Look for it in mid-October. It’s an ambitious attempt to explore the relevance of major past climate change to today. In particular, we look at the last interglacial, the Eemian, when sea levels rose to somewhere between four and eight meters higher than today. Interestingly, temperatures were only modestly higher than today and carbon dioxide levels were substantially lower. That’s an example of the many twists and turns in the tangled history of our dynamic planet.

Thirty-six years ago this month, on Sept. 5, 1977, the Voyager 1 spacecraft was launched from Cape Canaveral, Fla.

On September 12, 2013, NASA officially confirmed that Voyager 1 had reached the interstellar medium in August 2012. This makes Voyager 1 the first spacecraft to exit our solar system, a mark in history to be remembered forever.

Hear what today’s leading Astro-celebs have to say about Voyager’s incredible landmark accomplishment!

This edition of COSMIC JOURNEYS explores the still unfolding story of Earth’s past and the light it sheds on the science of climate change today. While that story can tell us about the mechanisms that can shape our climate. it’s still the unique conditions of our time that will determine sea levels, ice coverage, and temperatures.

Ice, in its varied forms, covers as much as 16% of Earth’s surface, including 33% of land areas at the height of the northern winter. Glaciers, sea ice, permafrost, ice sheets and snow play an important role in Earth’s climate. They reflect energy back to space, shape ocean currents, and spawn weather patterns.

But there are signs that Earth’s great stores of ice are beginning to melt. To find out where Earth might be headed, scientists are drilling down into the ice, and scouring ancient sea beds, for evidence of past climate change. What are they learning about the fate of our planet… a thousand years into the future and even beyond?

30,000 years ago, Earth began a relentless descent into winter. Glaciers pushed into what were temperate zones. Ice spread beyond polar seas. New layers of ice accumulated on the vast frozen Continue reading Cosmic Journeys – Earth in 1000 Years →

Dive into Titan’s thick atmosphere and find out what a strange place it is, adapted from NASA’s Scientific Visualization Studio. With its clouds, rain cycle, and giant lakes, Saturn’s large moon Titan is a surprisingly Earthlike place. But unlike on Earth, Titan’s surface is far too cold for liquid water – instead, Titan’s clouds, rain, and lakes consist of liquid hydrocarbons like methane and ethane (which exist as gases here on Earth). When these hydrocarbons evaporate and encounter ultraviolet radiation in Titan’s upper atmosphere, some of the molecules are broken apart and reassembled into longer hydrocarbons like ethylene and propane.

NASA’s Voyager 1 spacecraft first revealed the presence of several species of atmospheric hydrocarbons when it flew by Titan in 1980, but one molecule was curiously missing – propylene, the main ingredient in plastic number 5. Now, thanks to NASA’s Cassini spacecraft, scientists have detected propylene on Titan for the first time, solving a long-standing mystery about the solar system’s most Earthlike moon.