Author Archives: Damian Allis

NASA Night Sky Notes: Summer Triangle Corner – Deneb

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. Your tax dollars help promote science! The following article was provided for reprinting by the Night Sky Network in August, 2020.

By David Prosper

The Summer Triangle is high in the sky after sunset this month for observers in the Northern Hemisphere, its component stars seemingly brighter than before, as they have risen out of the thick, murky air low on the horizon and into the crisper skies overhead. Deneb, while still bright when lower in the sky, now positively sparkles overhead as night begins. What makes Deneb special, in addition to being one of the three points of the Summer Triangle? Its brilliance has stirred the imaginations of people for thousands of years!

Deneb is the brightest star in Cygnus the Swan and is positioned next to a striking region of the Milky Way, almost as a guidepost. The ancient Chinese tale of the Cowherd (Niulang) and the Weaver Girl (Zhinü) – represented by the stars Altair and Vega – also features Deneb. In this tale the two lovers are cast apart to either side of the Milky Way, but once a year a magical bridge made of helpful magpies – marked by Deneb – allows the lovers to meet. Deneb has inspired many tales since and is a staple setting of many science fiction stories, including several notable episodes of Star Trek.

Astronomers have learned quite a bit about this star in recent years, though much is still not fully understood – in part because of its intense brightness. The distance to Deneb from our Sun was measured by the ESA’s Hipparcos mission and estimated to be about 2,600 light years. Later analysis of the same data suggested Deneb may be much closer: about 1,500 light years away. However, the follow-up mission to Hipparcos, Gaia, is unable to make distance measurements to this star! Deneb, along with a handful of other especially brilliant stars, is too bright to be accurately measured by the satellite’s ultra-sensitive instruments.

Deneb is unusually vivid, especially given its distance. Generally, most of the brightest stars seen from Earth are within a few dozen to a few hundred light years away, but Deneb stands out by being thousands of light years distant! In fact, Deneb ranks among the top twenty brightest night time stars (at #19) and is easily the most distant star in that list. Its luminosity is fantastic but uncertain, since its exact distance is also unclear. What is known about Deneb is that it’s a blue-white supergiant star that is furiously fusing its massive stocks of thermonuclear fuel and producing enough energy to make this star somewhere between 50,000 and 190,000 times brighter than our Sun if they were viewed at the same distance! The party won’t last much longer; in a few million years, Deneb will exhaust its fuel and end its stellar life in a massive supernova, but the exact details of how this will occur, as with other vital details about this star, remain unclear.

Discover more about brilliant stars and their mysteries at

Long exposure shot of Deneb (brightest star, near center) in its richly populated Milky Way neighborhood. Photo credit: Flickr user jpstanley. Source: License:
Spot Vega and the other stars of the Summer Triangle by looking straight up after sunset in August!

The Night Sky Network program supports astronomy clubs across the USA dedicated to astronomy outreach. Visit to find local clubs, events, and more!

NASA Night Sky Notes: Mars’s Latest Visitor – NASA’s Perseverance Rover

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. Your tax dollars help promote science! The following article was provided for reprinting by the Night Sky Network in July, 2020.

By David Prosper

NASA’s latest Mars rover, Perseverance, is launching later this month!  This amazing robot explorer will scout the surface of Mars for possible signs of ancient life and collect soil samples for return to Earth by future missions. It will even carry the first off-planet helicopter: Integrity. Not coincidentally, Perseverance will be on its way to the red planet just as Mars dramatically increases in brightness and visibility to eager stargazers as our planets race towards their closest approach in October of this year.  

Perseverance’s engineers built upon the success of its engineering cousin, Curiosity, and its design features many unique upgrades for a new science mission! In February of 2021, Perseverance will land at the site of an ancient river delta inside of Jezero Crater and ready its suite of seven primary scientific instruments. The rover will search for traces of past life, including possible Martian fossils, with WATSON and SHERLOC, two advanced cameras capable of seeing tiny details. The rover also carries an amazing instrument, SuperCam, to blast rocks and soil outside of the rover’s reach with lasers to determine their chemical makeup with its onboard suite of cameras and spectrometers.  Perseverance will also take core samples of some of the most promising rocks and soil, storing them for later study with its unique caching system. Future missions will retrieve these samples from the rover and return them for detailed study by scientists on Earth.  Perseverance also carries two microphones so we can hear the sounds of Mars and the noises of its instruments at work. It will even launch a small helicopter – Ingenuity – into the Martian atmosphere as a trial for future aerial exploration!

Would you like to contribute to Mars mission science? You can help NASA’s rover drivers safely navigate the Martian surface by contributing to the AI4Mars project! Use this tool to label terrain features on photos taken of the Martian surface by NASA missions to help train an artificial intelligence algorithm to better read their surrounding landscape:           

The launch of Mars Perseverance is, as of this writing, scheduled for July 20, 2020 at 9:15am EDT. More details, updates, and livestreams of the event are available on NASA’s official launch page: . Dig deep into the science of the Mars 2020 mission and the Perseverance rover at: . Find out even more about past, present, and future Mars missions at

Perseverance inspects a cluster of interesting Martian rocks with its instruments in this artist rendering by NASA JPL/Caltech
Observe Mars yourself over the next few months! Mars can be found in early morning skies throughout July, and by the end of the month will rise before midnight. Mars gradually brightens every night until the close approach of Mars in October. The pre-dawn skies of July 17 present an especially nice view, as the waning crescent Moon will appear near Venus and Aldebaran.

The Night Sky Network program supports astronomy clubs across the USA dedicated to astronomy outreach. Visit to find local clubs, events, and more!

Free Astronomy Magazine – July-August 2020 Issue Available For Reading And Download

And Happy 4th, fellow astrophiles!

The most recent issue of Free Astronomy Magazine (July-August 2020) is available for your reading and downloading pleasure at (click the link to go directly to the issue).

July-August 2020 includes a selected survey of astronomical content of local and cosmological interest from NASA/ESA, ESO, ALMA, as well as three feature articles from our fearless leader/editor Michele Ferrara. The feature articles in this issue discuss:

  1. “All the planets of Proxima Centauri” – the science for this article was quite literally being published as the article itself was being put together, about as fast a processing of journal-article-to-magazine as one can do while putting others together.
  2. “A supernova or Sagittarius – which should we thank?” – I’ve mentioned in many lectures that our own Sun is either the second or third stellar inhabitant in our vicinity, with a local supernova sparking the formation of it and our Solar System way back when. Recent studies indicate that other events 5-ish billion years ago might have instigated the events that lead to “us.”
  3. “The principle of mediocrity and the habitability of galaxies” – lump this use of the word “mediocrity” with the scientific use of the word “theory,” please. It is a joy to know that fundamental debates are being had in the astronomy and astrophysics literature and that there remains plenty, plenty yet to know for those pondering their futures in STEM.

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

The web browser-readable version:

Jump right to the PDF download (15 MB): July-August 2020