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Most of North America gets to see the Moon blot out Antares Thursday night.

The long drought of lunar bright star occultations ends this week, as the Moon meets the bright star Antares. This event is one of the best bright star versus the Moon occultations for 2023, and is a harbinger for a series of new occultations of the star once every pass, as the Moon swings through Scorpius the Scorpion every lunar synodic period or 29.5 days.

Despite the cryptic-sounding name, occultations in astronomy are simply when one object passes in front of another, blocking out the light from the more distant object. These can involve planets, asteroids, or as in this week’s case, the Moon and a bright star. In the current epoch, four bright stars lay along the Moon’s celestial path: Spica, Regulus, Aldebaran and Antares (Alpha Scorpii).

Occultation
The occultation of Aldebaran by the Moon in 2016. Credit: Andrew Symes.

Why Occultations Are Important to Astronomy

Lunar occultations can also yield useful scientific data: for example, these events can reveal close double stars seen as they wink out on the limb of the Moon in a step-wise fashion. Grazing events can be especially dramatic, as the star plays hide-and-seek along the lunar limb, revealing peaks and valleys along the Moon’s profile.

Occultations were even used by navigators of yore, to get a fix on their location at sea:

#OnThisDay April 26th, 1614 -English navigator William Baffin observing from the H.M.S. Discovery used an occultation of the bright star Antares by the Moon to get a one time fix of longitude at sea: https://t.co/LYgSvzNLnC #history #astronomy #otd pic.twitter.com/PO1NPFEiHv

— Dave Dickinson (@Astroguyz) April 26, 2019

The August 25th Antares occultation favors most of North America at dusk. It’s still worth checking out the event even if you’re outside the footprint, as the Moon and Antares will make a nice pairing worldwide.

Occultation
The visibility footprint for the August 25th occultation. Credit: Occult 4.2

Central conjunction for the event occurs on Friday, August 25th at 2:06 Universal Time (UT), which is currently six hours ahead of U.S. East Coast time. The Moon is 58% illuminated, waxing gibbous during the event, contrasting with +1st magnitude Antares. All that light from Antares took 554 years to get here, only to be blocked out in the last instant.

The International Occultation Timing Association (IOTA) has a list of times for the Antares occultation here.

Dark Limb Ingress

Occultations during waxing phase are always particularly entrancing, as the dark limb of the Moon leads the way, obscuring the star or planet during ingress. Antares will return to view about an hour later during egress. Observers across northern Mexico and central Florida will be treated to an especially dramatic view, as Antares grazes the southern limb of the Moon. Most of Canada, northern Mexico and the contiguous United States (CONUS) sees the occultation transpire under dark skies, while Baja California and the southwestern United States sees the event in twilight.

And Spica makes two. This is the first of 68 occultations of Antares by the Moon, running out to August 27th, 2028. Spica joins the lunar occultation hit parade in 2024, with 20 events running out to November 17th, 2025.

How to Observe Thursday’s

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The Kuiper Belt is Much Bigger Than We Thought

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NASA’s New Horizons spacecraft is just over 8.8 billion km away, exploring the Kuiper Belt. This icy belt surrounds the Sun but it seems to have a surprise up its sleeve. It was expected that New Horizons would be leaving the region by now but it seems that it has detected elevated levels of dust that are thought to be from micrometeorite impacts within the belt. It suggests perhaps that the Kuiper Belt may stretch further from the Sun than we thought! 

The Kuiper Belt is found beyond the orbit of Neptune and is thought to extend out to around 8 billion km. Its existence was first proposed in the mid-20th century by Gerard Kuiper after whom the belt has been named. It’s home to numerous icy bodies and dwarf planets and offers valuable insight into the formation and evolution of the Solar System.

Launched by NASA in January 2006 atop an Atlas V rocket, the New Horizon’s spacecraft embarked on its mission to explore the outer Solar System. The primary objective was to perform a close flyby of Pluto, which it did 9.5 years after it launched, and continue on to explore the Kuiper Belt.

New Horizons completed its flyby of Pluto in 2015, and has been travelling through the Kuiper Belt since. As it travels through the outer reachers of the region, almost 60 times the distance from Earth to the Sun, its Venetia Burney Student Dust Counter (SDC) has been counting dust levels. The instrument was constructed by students at the Laboratory for Atmospheric Space Physics at the University of Colorado Boulder. Throughout New Horizon’s journey, SDC has been monitoring dust levels giving fabulous insight into collision rates among objects in the outer Solar System. 

The New Horizons instrument payload that is currently doing planetary science, heliospheric measurements, and astrophysical observations. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
The New Horizons instrument payload that is currently doing planetary science, heliospheric measurements, and astrophysical observations. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The dust particle detections announced in a recent paper published in the Astrophysical Journal Letters by lead author Alex Doner are thought to be frozen remains from collisions between larger Kuiper Belt Objects (KBOs). The results were a real surprise and challenged the existing models that predicted a decline in dust density and KBO population. It seems that the belt extends many billions of miles beyond the current estimates or maybe even that there is a second belt!

The results came from data gathered over a three year period during New Horizon’s journey from 45 to 55 astronomical units (where 1 astronomical unit is the average distance between the Sun and Earth). While New Horizon’s was gathering data about dust, observatories such as the 8.2-meter optical-infrared Subaru Telescope in Hawaii have been making discoveries of new KBOs. Together these findings suggest the Kuiper Belt objects and dust may well extend a further 30 AUs out to about 80 AUs from the Sun.

New Horizons is now in its extended mission and hopefully has sufficient power and propellant to continue well into the 2040s. At its current velocity that will take the spacecraft out to about 100 AU from the Sun so the research team speculate that the SDC could identify the transition point into interstellar space.

Source : NASA’s New Horizons Detects Dusty Hints of Extended Kuiper Belt

The post The Kuiper Belt is Much Bigger Than We Thought appeared first on Universe Today.

Did you miss our previous article…
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A Planetary Disk in the Orion Nebula is Destroying and Replenishing Oceans of Water Every Month

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Planet-forming disks are places of chaotic activity. Not only do planetesimals slam together to form larger worlds, but it now appears that the process involves the destructive recycling of water within a disk. That’s the conclusion from scientists studying JWST data from a planetary birth crèche called d203-506 in the Orion Nebula.

The data they studied suggest that an amount of water equivalent to all of Earth’s oceans is created and replenished in a relatively short period—about a month. According to study co-lead Els Peeters at Western University in Canada, it was relatively easy to discover this process in the protoplanetary disk. “This discovery was based on a tiny fraction of our spectroscopic data,” she said. “It is exciting that we have so much more data to mine and I can’t wait to see what else we can find.”

The Orion Nebula is a vast active star- and planet-forming region and the d203-506 protoplanetary disk lies within it at a distance of about 1,350 light-years away from Earth. Astronomers study the nebula to understand all aspects of star birth since there are so many newborn stars there. In addition, many are surrounded by disks of gas and dust, called protoplanetary disks (proplyds, for short). Those regions are excellent places to observe planet-formation processes, and particularly the interplay between the young stars and their disks.

The Orion Nebula, one of the most studied objects in the sky. It's likely that many of its protostars and their planetary disks contain water in some form. Image: NASA
The Orion Nebula is one of the most studied objects in the sky. Many of its protostars and their planetary disks likely contain water in some form. Image: NASA

The Water Cycle of a Proplyd

We all know that water is an important ingredient for life. It certainly played a role in creating and sustaining life on our planet. As it turns out, water is a significant fraction of the materials in a proplyd. In the infant Solar System, water existed throughout our proplyd long before any of the planets formed, largely in their icy form, either as icy bodies or locked into asteroids and planetesimals. It also exists in interstellar space.

This view of Earth’s horizon was taken by an Expedition 7 crewmember onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean. A new study suggests that Earth's water didn't all come from comets, but likely also came from water-rich planetesimals.  Credit: NASA
This view of Earth’s horizon by an Expedition 7 crewmember onboard the International Space Station. A new study suggests that Earth’s water didn’t all come from comets, but likely also came from water-rich planetesimals. Credit: NASA

Most of Earth’s water got delivered to the forming planet over millions of years. It melted or outgassed to form the oceans, rivers, and lakes we see today. But, some fraction of the water in our system’s birth disk probably went through a “freeze-thaw” cycle within the disk. That happened when the Solar System was still just a disk of gas and dust. The water was essentially destroyed and then re-formed at higher temperatures.

We can’t see that effect anymore in our system. But, astronomers can point telescopes at other proplyds to see if the same process happens there. That’s what Peeters and her team did. They used JWST to look at d203-506. There, bright young stars flood the nearby regions in the proplyd with intense ultraviolet radiation. The UV breaks up water molecules to form hydroxyl molecules and that process also releases infrared light. JWST can search out that light and report back on how much hydroxyl
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The 12 Best Hikes in Utah’s National Parks

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By Michael Lanza

From natural arches, hoodoos, and hanging gardens to balanced rocks and towering mesas, slot canyons and vast chasms, the desert Southwest holds in its dry, searing, lonely open spaces some of America’s most fascinating and inspiring geology. The writer “Cactus Ed” Abbey no doubt had this region in mind when he said there “are some places so beautiful they can make a grown man break down and weep.” Much of it sits protected within southern Utah’s five national parks: Zion, Bryce Canyon, Arches, Canyonlands, and Capitol Reef.

The good news? Many of the best sights can be reached on dayhikes of anywhere from a couple hours to a full day.

A hiker below the Wall of Windows on the Peek-a-Boo Loop in Bryce Canyon National Park.
” data-image-caption=”Cyndi Hayes hiking below the Wall of Windows on the Peek-a-Boo Loop in Bryce Canyon National Park.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?fit=300%2C199&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?fit=900%2C598&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?resize=900%2C598&ssl=1″ alt=”A hiker below the Wall of Windows on the Peek-a-Boo Loop in Bryce Canyon National Park.” class=”wp-image-43917″ srcset=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?resize=1024%2C680&ssl=1 1024w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?resize=300%2C199&ssl=1 300w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?resize=768%2C510&ssl=1 768w, https://i0.wp.com/thebigoutside.com/wp-content/uploads/2020/02/Bryce2-013-Wall-of-Windows-Peek-a-Boo-loop-Bryce-Canyon-UT.jpg?w=1200&ssl=1 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Cyndi Hayes hiking below the Wall of Windows on the Peek-a-Boo Loop in Bryce Canyon National Park.
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Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-books to classic backpacking trips. Click here to learn how I can help you plan your next trip.

The list below of the best dayhikes in southern Utah’s national parks derives from numerous trips I’ve made to each of these parks over the past three decades, including the 10 years I spent as a field editor for Backpacker magazine and even longer running this blog. Use my list as your compass, and I guarantee you will knock off the best hikes in these parks.

I’d love to read your thoughts about my list—and your suggestions for dayhikes that belong on it. Please share them in the comments section at the bottom of this story. I try to respond to all comments, and as I continue to explore more trails, I will regularly update this story.

A teenage boy hiking Angels Landing, Zion National Park.
” data-image-caption=”My son, Nate, hiking Angels Landing in Zion National Park.
” data-medium-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/09/Zion5-015-Angels-Landing-Zion-National-Park.-copy.-copy.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/09/Zion5-015-Angels-Landing-Zion-National-Park.-copy.-copy.jpg?fit=900%2C600&ssl=1″ src=”https://i0.wp.com/thebigoutside.com/wp-content/uploads/2019/09/Zion5-015-Angels-Landing-Zion-National-Park.-copy.-copy.jpg?resize=900%2C600&ssl=1″ alt=”A teenage boy hiking Angels Landing, Zion National Park.” class=”wp-image-35512″ srcset=”https://i0.wp
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