Pic of the Week: Europa in All its Glory

Posted on by onespaceman2000
Image (Credit): Hubble images of Jupiter’s moon Europa. (NASA, NASA-JPL, University of Arizona)

This week’s photo of Jupiter’s moon Europa was taken by the Hubble Space Telescope in June 1997 (and released by NASA on October 14, 2021). Here is the story about these two images (the left one in natural color and the right one enhanced) from the Hubble site:

This photograph of the Jovian moon Europa was taken in June 1997 at a range of 776,700 miles by NASA’s Galileo spacecraft.

Slightly smaller than Earth’s moon, Europa has a very smooth surface and the solid ice crust has the appearance of a cracked eggshell. The interior has a global ocean with more water than found on Earth. It could possibly harbor life as we know it.

Hubble Space Telescope observations of Europa have revealed the presence of persistent water vapor in its very tenuous atmosphere. Hubble observations, spanning 1999 to 2015, find that water vapor is constantly being replenished throughout one hemisphere of the moon. This is a different finding from Hubble’s 2013 observations that found localized water vapor from geysers venting from its subsurface ocean. This water vapor comes from a different process entirely. Sunlight causes the surface ice to sublimate, transitioning directly into gas.

This color composite Galileo view combines violet, green, and infrared images. The view of the moon is shown in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa’s surface is composed mostly of water ice, with very few non-ice materials. Long, dark lines are fractures in the crust, some of which are more than 1,850 miles long.

Largest Comet to Date Approaching the Sun

Posted on by onespaceman2000
Image (Credit): Comparison of comet C/2014 UN271 (Bernardinelli-Bernstein) to several other comets. (NASA, ESA, Zena Levy (STScI))

A monster comet that takes 3 million years to circle the Sun is being closely analyzed by astronomers. The comet, C/2014 UN271 (Bernardinelli-Bernstein), will come closest to the Sun in 2031, but even then it will be about 1 billion miles away. At the most distant point in its orbit, the comet is about half a light year away from the Sun.

As shown in the graphic above, this is a large comet that could fully cover the state of Rhode Island. It was first detected by astronomers back in November 2010, when it was still 3 billion miles from the Sun. With the help of the Hubble Space Telescope, the astronomers were able to learn more about it this year.

The comet is believed to be a product of the Oort Cloud circling far outside our solar system. Of course, the Oort Cloud itself is a theory that has never been directly observed. But what about the Voyager spacecraft that left our solar system? Well, if you are willing to wait another 300 years, and the spacecraft are still working, you may have an answer.

You can read more about the comet at this NASA site.

Pic of the Week: Final Acts of a Monster Star

Posted on by onespaceman2000
Image (Credit): The nebula surrounding the star AG Carinae (ESA/Hubble and NASA, A. Nota, C. Britt)

This week’s photo is from the Hubble Space Telescope. It shows the “puffing dust bubbles and an erupting gas shell,” or nebula, surrounding the monster star AG Carinae. Here is the rest of the story from the European Space Agency (ESA) Hubble site:

This giant star is waging a tug-of-war between gravity and radiation to avoid self-destruction. The star is surrounded by an expanding shell of gas and dust — a nebula — that is shaped by the powerful winds emanating from the star. The nebula is about five light-years wide, equal to the distance from here to our nearest star, Alpha Centauri.

AG Carinae is formally classified as a Luminous Blue Variable because it is hot (blue), very luminous, and variable. Such stars are quite rare because there are not many stars that are so massive. Luminous Blue Variable stars continuously lose mass in the final stages of their life, during which a significant amount of stellar material is ejected into the surrounding interstellar space, until enough mass has been lost that the star has reached a stable state. 

AG Carinae is surrounded by a spectacular nebula, formed by material ejected by the star during several of its past outbursts. The nebula is approximately 10 000 years old, and the observed velocity of the gas is approximately 70 kilometres per second. While this nebula looks like a ring, it is in fact a  hollow shell rich in gas and dust, the centre of which has been cleared by the powerful stellar wind travelling at roughly 200 kilometres per second. The gas (composed mostly of ionised hydrogen and nitrogen) is visible to us in these images as a thick bright red ring, which appears doubled in places — possibly the result of several outbursts colliding into each other. The dust, here visible in blue, has formed in clumps, bubbles and filaments that are shaped by the stellar wind.

This image was selected by the ESA for the month of April in its 2022 ESA/Hubble Calendar.

Pic of the Week: The Morning Star

Posted on by onespaceman2000
Image (Credit): View of the Earendel star from the Hubble Space Telescope. (NASA)

This week’s image is the most distant star ever detected. It is from light that traveled 12.9 billion years to get to us, representing a star that existed about 1 billion years after the formation of the universe. It has been named Earendel, or “morning star” in Old English. You can learn more about this image from NASA’s Hubble site:

The find is a huge leap further back in time from the previous single-star record holder; detected by Hubble in 2018…The newly detected star is so far away that its light has taken 12.9 billion years to reach Earth, appearing to us as it did when the universe was only 7 percent of its current age, at redshift 6.2. The smallest objects previously seen at such a great distance are clusters of stars, embedded inside early galaxies…The research team estimates that Earendel is at least 50 times the mass of our Sun and millions of times as bright, rivaling the most massive stars known. But even such a brilliant, very high-mass star would be impossible to see at such a great distance without the aid of natural magnification by a huge galaxy cluster, WHL0137-08, sitting between us and Earendel. The mass of the galaxy cluster warps the fabric of space, creating a powerful natural magnifying glass that distorts and greatly amplifies the light from distant objects behind it…Astronomers expect that Earendel will remain highly magnified for years to come. It will be observed by NASA’s James Webb Space Telescope. Webb’s high sensitivity to infrared light is needed to learn more about Earendel, because its light is stretched (redshifted) to longer infrared wavelengths due to the universe’s expansion.

Image (Credit): Detailed view pinpointing the Earendel star from the Hubble Space Telescope. (NASA)

Pic of the Week: Space Triangle

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Image (Credit): Space Triangle image from the Hubble Space Telescope. (NASA, ESA, STScI, Julianne Dalcanton with the Center for Computational Astrophysics/Flatiron Inst., UWashington)

This week’s image is from the Hubble Space Telescope. It shows the collision of spiral galaxy NGC 2445 on the right and NGC 2444 on the left, creating what appears to be a triangle of new stars. Here is a little more on the pair from NASA’s Hubblesite:

A spectacular head-on collision between two galaxies fueled the unusual triangular-shaped star-birthing frenzy, as captured in a new image from NASA’s Hubble Space Telescope…

Astronomers suggest that the galaxies passed through each other, igniting the uniquely shaped star-formation firestorm in NGC 2445, where thousands of stars are bursting to life on the right-hand side of the image. This galaxy is awash in starbirth because it is rich in gas, the fuel that makes stars. However, it hasn’t yet escaped the gravitational clutches of its partner NGC 2444, shown on the left side of the image. The pair is waging a cosmic tug-of-war, which NGC 2444 appears to be winning. The galaxy has pulled gas from NGC 2445, forming the oddball triangle of newly minted stars.