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A weekly discussion of what’s new and interesting in astronomy with Dr. Derrick Pitts
146 Episodes
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Happy Birthday, Carl!

Happy Birthday, Carl!

2019-11-0900:07:02

November 9th marks the anniversary of legendary astronomer Carl Sagan’s birth. Sagan was known for his wonderfully poetic way of explaining and transporting listeners into the history and complexities of the universe. He explored the mysteries of outer space in his landmark PBS program, “Cosmos: A Personal Voyage.”Monday is Mercury Transit Day: The planet Mercury will cross between Earth and the Sun. The transit starts at 7:36 am EST and ends at 1:04 pm. Those hoping to witness the transit must ensure they have proper eye protection. Alternatively, head to the Franklin Institute to watch through their telescopes.It happens about 13 times per century – and the next opportunity comes in the year 2032. It can’t happen on every orbit because Mercury’s orbit is tilted slightly from Earth’s. That means our orbits align only twice a year, so only during those times can Venus and Mercury be seen crossing the sun’s disk in transit. Sizing Up Dwarf Planets:Hygeia, which is only 270 miles (Philadelphia to Virginia Beach) in diameter, is now designated as the smallest dwarf planet discovered so far! Hygeia qualifies even though it’s so small because it apparently has enough mass to pull itself into a spherical shape.
Special Delivery

Special Delivery

2019-11-0200:05:19

An International Space Station Resupply Mission is scheduled to launch from Wallops Island, Virginia, at the Mid-Atlantic Regional Spaceport (MARS). It will transport 8,200 lbs of research, crew supplies, and hardware to the six-person crew on the ISS. The craft arrives at ISS at 4:30 am on Monday. We bid adieu to Daylight Saving Time when we shift our clocks back one hour at 2:00 am on Sunday, November 3rd. Next – we mark the earliest sunset in early December.Take advantage of the earlier nightfall: Jupiter and Saturn are still available to be seen in the southwest after sunset, Venus rising out of the west as well. Mars has the pre-dawn sky now.
Matter Barely Matters

Matter Barely Matters

2019-10-2600:05:58

This Thursday is Halloween…and Dark Matter Day! Dark matter-themed events are being organized by labs and institutions around the world doing this research. They range from live webcasts with researchers to dark matter scavenger hunts to a Reddit AMA. Find a sortable list at www.darkmatterday.com/events-listScientists believe that dark matter, which we have so far only detected through its gravity-based effects in space, makes up about a quarter (26.8 percent) of the total mass and energy of the universe, and something that is driving the universe’s accelerating expansion, which scientists call dark energy, accounts for another 68.3 percent.The ordinary matter, like stars and planets and galaxies, makes up just 4.9 percent of the total mass and energy of the universe.So there’s a BIG part of the universe that we don’t know much about. We’re not sure if dark matter is made up of undiscovered particles, or if it can be explained by tweaking the known laws of physics. Its makeup could teach us much about the history and structure of our universe.Could dark matter play a role in the composition of newly detected spiral galaxies that dwarf our Milky Way? Recently discovered Super Spiral Galaxies are 180,000 to 440,000 light years across! Our Milky Way is a pretty big galaxy as galaxies go, but it’s a mere 100,000 light years across. These super spirals have so much mass that they spin up to three times faster than galaxies the size of our Milky Way. The spin seems to be much faster than the visible mass should allow. No worries, researchers have pinned the blame on, you guessed it, Dark Matter!Astronomer Vera Rubin postulated that galaxies had large amounts of unseen mass that affected their gravitational component: What we now know as dark matter. The extraordinary rotational speeds could be accounted for if there’s a halo of dark matter surrounding the enormous galaxy. The largest of the observed galaxies seems to have 40 trillion solar masses worth of dark matter; that’s 40 trillion suns worth, more than 100 times the amount of stars in Milky Way type galaxies! 100 of these galaxies have been identified so far.
Dinner on Mars?

Dinner on Mars?

2019-10-1900:09:11

A group of researchers at Wageningen University in the Netherlands have successfully grown edible food crops in soils that simulate the soil composition of the Moon and Mars. Garden cress, radish, spinach, quinoa, tomato, rye, chives, leek and peas were all harvested in this most recent study. Crops did better in the Martian soil than the lunar soil and spinach didn’t like either soil simulant. An earth soil ‘control’ was used.The most intriguing finding from the study is that common crops can grow in Moon/mars soils simulants augmented with a compost-like supplement.October 21st is the 96th anniversary of the first-ever planetarium show at the Deutches Museum in Munich, Germany.Fels Planetarium was the second planetarium to open in the United States in January 1934. October 22nd is the 4,155th anniversary of the first record of a solar eclipse. In China where prediction of eclipses for the legitimacy of the Emperor, according to legend, two court astronomers were beheaded because they failed to predict an eclipse in 2136 BCE. Today mathematicians have calculated every eclipse from 1990 BCE to 3000! The next solar eclipse in the US is April 8, 2024. However, there won’t be another solar eclipse visible in Philadelphia until 2079. The last total eclipse in Philadelphia took place in 1478.The Orionid meteor shower peak arrives Tuesday morning. They’re very fast not so bright but leave persistent trails for several seconds. 10-20/hour and there are occasional bight ones that break up into fragments. Jupiter and Saturn are still holding court in the evening, with Venus just poking up from the west after sunset. In the pre-dawn sky, Mars weakly shows in the East around 6:30am.
Keeping Score

Keeping Score

2019-10-1200:06:43

Saturn pulls ahead of Jupiter in the number of moons detected – current score: 82 to 79Researchers recently announced the discovery of 20 new moons orbiting Saturn by using big telescopes at Hawaii’s Mauna Kea observatory equipped with very sensitive detectors. 17 of them orbit backwards, opposite the planet’s direction of rotation, and most of the new ones are about three miles in size. The current idea about their origin is that they are the detritus left over from the breakup of a moon not long after Saturn’s formation billions of years ago.When we think about all the energetic activity happening out there in the universe – supermassive black holes, millisecond pulsars, colliding neutron stars, exploding supernovae – it’s nice to know that in our little corner of the universe not much is happening, right? Hold your horses, because maybe we’re just in between happenings. Astronomers announced earlier this week that evidence has been detected that an enormous flare of ionizing radiation suddenly and explosively erupted from a source near the center of our galaxy. It was so powerful and extensive that evidence was found in gas stream 200,000 light years out in space! Just as surprising as this discovery is, the researchers determined that it took place just 3.5 million years ago! The Chixulub impact that triggered the great dinosaur die-off occurred 62 million years earlier! Our ancestors were just going walk-about on the African continent when this explosion occurred. So perhaps we’ve evolved in a relatively quiet period in the life of our galaxy. Remember, the evolution of the planet, solar system, galaxy and universe occurs over millions and billions of years and our studies only allow us to look at snapshots – instants in time which we try to assemble into a rational process that will allow us to reasonably predict what will happen in the future. BUT, we have a small number of ‘snapshots’ we’re trying to work with.There are merely three days left to enter your idea for an exoplanet nameInternational Astronomical Union U.S. has an exoplanet and the IUA naming committee is asking the American public to submit their suggestions. You can do it all online and it’s a great short project for a school to jump on!We’re running out of time to see Jupiter and Saturn in the evening sky.The Franklin Institute’s Night Skies at the Observatory program this Tuesday night Oct. 15, will show Saturn telescopically for the last time this season.
Rocket Man

Rocket Man

2019-10-0500:05:03

Saturday, October 5th is the 132nd birth anniversary of rocket pioneer Robert H. Goddard. His was the first liquid-fueled rocket to prove the concept that allowed for the exploration of space as we know it today. He launched the first liquid-fueled rocket in March 1926. The maximum altitude he achieved was 1.7 miles. His technology eventually was adopted in America soon after his death in 1945.October 5th is also the 61st anniversary of the founding of NASA. It was originally established as the National Advisory Committee for Aeronautics, and had 8000 employees and three laboratories. President Dwight Eisenhower signed the National Aeronautics and Space Act in August 1958 in response to the launch of Sputnik on October 4th, 1957. Congress created the National Aeronautics and Space Administration on October 1st, 1958. Along with our seasonal weather change comes the now obvious changes in sun time. We’re down to 11 hours 36 minutes of sun above the horizon vs 15 hours on June 21. We’ll still lose another 2 hours and 15 minutes between now and December 21 with Halloween as the halfway point to Winter Solstice. This is a great time for stargazers because they can start early enough and be warm enough to see three seasons of constellations from sunset to sunrise. Jupiter and Saturn are still the showpiece items of the evening sky.On Sunday night at 8 p.m., 60 degrees up in the NorthEast, the International Space Station will be visible.
Looking for Goldilocks

Looking for Goldilocks

2019-09-2800:05:54

Weeks ago, an announcement about the discovery on an exoplanet where it appeared possible for an atmosphere with precipitation to exist led it to be described as an “earthlike planet,” and suggestions were made about its potential habitability. Very little was said about its structure being far more like Jupiter mostly gas with a tiny rocky core very far below the cloud tops. That’s an important component of the composition in a description mentioning ‘habitability’ and ‘earthlike’.Mass determines if the object produces a gravity field capable of holding an atmosphere for some length of time. Venus and Earth are massive enough, Mars was only able to hold a thick atmosphere for a comparatively short period early in its history.Position relative to their host star: the ‘Goldilocks (habitable) Zone’ ideally looking for a distance where water can exist as a liquid.Density of exoplanet candidate ‘Hot Jupiters’ have been identified as Jupiter-sized objects (big size, low density) with short orbital periods orbit close to their host star.What type of star is hosting the exoplanet(s)? Cool, mid-temp or hot(Lo mass vs hi mass)?This has implications for the composition of the planet and the dynamics of planetary formation in that star system. We are as yet unable to gather enough data to clearly identify something as TRULY earthlike. We can use only inference to determine mass, density, size and transmission spectroscopy to get any kind of handle on atmospheric composition.Turning to night sky highlights this week:Jupiter and Saturn still hold court in the South/Southwest evening sky. The moon is at its new phase today so look for a thin crescent emerging from the west just after sunset tomorrow, Sunday, and Monday evenings.
What’s in a name?

What’s in a name?

2019-09-1400:04:49

The International Astronomical Union (IAU) is putting out the call on its 100th anniversary to name an exoplanet and its star.
Star Trekkin’

Star Trekkin’

2019-09-0700:05:09

The TV series ‘Star Trek’ premiered 53 years ago. The original series only lasted three seasons on prime time, but really hit its stride in syndication, where its popularity exploded. It also fueled fantasies for many other TV programs and films, and maybe even real life space exploration. The last day for filming was 1/8/69, six months before Apollo 11 left for the moon.September means a shorter number of minutes of sunlight; Sunrise now at 6:34am and sunset at 7:23pm.Taking advantage of the growing opportunities for night sky viewing; A waxing crescent moon sneaks up on Saturn tonight and zips past during the day tomorrow.Saturn is just above the top star of the teapot shape of Sagittarius and Jupiter is not far above the red giant star Antares of Scorpius.The two planets straddle the southern Milky Way galaxy, a fine target for binocular observing.
After a four-week journey from earth, the Indian Space Research Organization announced its Chandrayaan 2 spacecraft successfully entered lunar orbit. Next up in about a week is a landing attempt, then a rover deployment. The chosen landing location is the moon’s South Pole region. The orbiter is expected to operate for about a year and the lander and rover will perform surface studies. The rover is about 60 pounds and solar powered. The lander and rover are expected to last at least one lunar day (two weeks) but as lunar night comes flight controllers will try to awaken the rover and lander after the two-week sleep. India hopes to complete its first crewed mission by 2022.The Big Dipper is visible in the northwest just after dark and the main summer constellations Cygnus, Lyra, and Altair are overhead by 9:00pm. Catch three seasons of constellations in one overnight: Summer Triangle overhead at 9:30pm, Pegasus and Andromeda (w/ M31) in the east at 10:30pm, and Orion in the east at 5:00am-5:30am. The moon is next to Jupiter on the evening of the 5th and slides towards Saturn the next night.
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