Skytalk A weekly discussion of what's new and interesting in astronomy with astronomer Derrick Pitts



A weekly discussion of what's new and interesting in astronomy with astronomer Derrick Pitts

Most Recent Episodes

50 Years On

"The Apollo Chronicles" by regional producer Rotfeld Productions premieres at The Franklin Institute next week at Night Skies Observatory (Tuesday, June 11). All four episodes, which reveal a new understanding of just how NASA's Apollo program came to be, will be featured at the Franklin Institute this month and next month leading up to the anniversary day itself (launched 7/16/69 – landed on the surface of the moon 7/20/69 – returned to Earth 7/24/69. On Tuesday the producers will share their journey of creation telling us their stories of how they acquired the unbelievable footage and interviews with flight engineers, flight controllers, politicians, and the astronauts themselves. In anticipation of a return to the moon; three commercial services begin providing lunar lander services to NASA through The Commercial Lunar Services Program. They will ferry up to 23 NASA provided payloads to three different locations where they'll conduct science investigations and demonstrate advances technologies in preparation for our return to the moon now proposed for 2024. In this case, NASA is a customer receiving service from a commercial provider. Missions are currently scheduled to begin dropping on the moon as early as September 2020 and all are expected to be completed by 2021. This Thursday makes the 16th year since solar system spacecraft Pioneer 10 left the solar system. Launched in 1972, it was the first spacecraft to reach the planet Jupiter. Last heard from in 2003, it's currently 11 billion miles out and headed toward Taurus, where in 90,000 years, it'll pass closer to a star (just under a light year) than any of the other four interstellar spacecraft will fly in the next few million

New Constellation On the Block

There is a new Constellation to see – and this one is artificial! The first set of satellites dedicated to eventually providing extremely low-cost internet access all over the world were launched into orbit last week. The first 60 of a proposed 12,000 member 'constellation' were launched aboard a SpaceX rocket and successfully placed in orbit. Each satellite is just 500 lbs. and has one solar panel but the coverage will be worldwide. While it might be seen as a boon providing everyone with internet access, it is adding 12,000 new satellites to the vast number of operating and defunct satellites now in orbit. How will they look? Heavens-Above dot com gives instructions for how to see what's being called a satellite train; the 60 sats are in a slowly dispersing line that can be seen from dark sky locations with the unaided eye. Currently the sats are at 277 miles altitude and orbit earth every 93 minutes. The first spacewalks were conducted 54 years ago: First by Soviet cosmonaut Alexi Leonov, (who celebrated his 85th birth anniversary this week) on March 18, 1965 and then three months later by American astronaut Ed White on June 3, 1965. Leonov's birthday was celebrated with a commemorative spacewalk by two cosmonauts, Oleg Kononenko and Alexi Ovchinin, aboard ISS just three days ago. Their six-hour spacewalk included the installation of hand rails on the Russian segment of ISS, retrieval of experiments from the Poisk module's hull and completion of other exterior maintenance. Leonov's groundbreaking effort lasted just 12 minutes. Can a dead star be reborn? Astronomers working at the University of Bonn in Germany have discovered an extremely rare find a very active star that seems to be the result of the collision of two white dwarf stars. Normally white dwarf stars just cool to darkness and obscurity. But these two seem to have had enough mass that their merger has generated enough heat and pressure to cause nuclear fusion to re-start in the combined core. Its fate? Only to eventually explode as a supernova when it finally runs out of energy – again.


The moon has two distinct faces; gravity readings of the moon's surface by a lunar orbiting satellite suggest that not long after formation of the original surface, another dwarf-planet-like object smacked into it causing the impacted side to be thrown upward and back to fold itself onto the back side of the moon. The best fit of some 360 simulations run by Meng Hua Zhu at the Space Science Institute of Macau University of Science and technology suggest an object about 480 miles in diameter and traveling at 22,500 mph, hit with enough force to re-surface the back side of the moon with up to six miles of layers from the front side. While the back or far side is commonly referred to as the "dark side," the moon receives equal amount of sunlight on each side, during the lunar day. Only one side of the Moon is visible from Earth because the Moon rotates on its axis at the same rate that the Moon orbits the Earth – a situation known as synchronous rotation, or tidal locking. Information from the European Space Agency Gaia satellite (providing precise distance and motion measurements for more than one billion stars) allows us to determine that at one time, our galaxy was making dozens of stars per year and that rate of production lasted for 5 billion years. Star production ebbed and flowed over the ensuing billions years bringing us to where we are now in production: just one solar-mass worth of stars per year. Yes, production will eventually end but not for billions of years. This is the final week to see Mars in the evening – it will be gone into the glare of sunset next week. Jupiter and Saturn are now pushing into the evening sky – Jupiter rising by 10:00 pm and Saturn by midnight. They're both visible in the pre-dawn sky straddling the southern Milky Way, bright Jupiter ahead of dimmer Saturn.

Celebrate Snoopy and the Gang

Today marks the 50th anniversary of the lunar landing dress rehearsal flight Apollo 10. Astronauts Tom Stafford, John Young and Gene Cernan took their lunar module nicknamed 'Snoopy' (the command module was nicknamed 'Charlie Brown')down to within 50,000 feet of the lunar surface, testing every aspect of performance of the craft especially the descent engine and rendezvous capability. The actual landing came just two months later with Apollo 11. Flight management provided only enough fuel in the Lunar Module to fly down to 50,000 ft and back to the command module. Why? They felt that Cernan and Young – both military test pilots – would probably try to reach the surface if they'd had enough fuel ! Young and Cernan flew on subsequent missions to the moon; Stafford flew on Apollo Soyuz. Blue Moon' is the latest entry into the lunar race. It's a 7,000-lb., 14ft tall landing vehicle designed by engineers at Blue origin space group. Currently, such a lander doesn't exist but Blue Origin believes it's already solved most of the challenges involved in assembling a workable lunar lander system. NASA names new missions to the moon after Apollo's twin sister Artemis (Greek mythology's goddess of the moon and the hunt. Orion was her hunting buddy). Cites the new diversity in the program and indicates that the 2024 return to the moon will include women. But we'd better go soon because the moon is shrinking! Not quickly by any means and not so as to change in any major observable way. Scientists looking at seismic data from sensors placed on the moon by Apollo 11, 12, 14, 15, 16 have determined that the moon is still shrinking as its interior cools from its creation 4.4 billion years ago. A re-analysis of data collected from the seismometers from 1968- 1977 combined with images from the Lunar Reconnaissance Orbiter, a lunar orbiting satellite that's been imaging the surface of the moon for more than 5 years, shows co-location between moonquake epicenters and thrust scarps on the lunar surface. As the interior cools and shrinks, the brittle outer crust squeezes, then throws one section over another section, creating stair-shaped cliffs. Mars is still hanging in the west sky at 9:00pm almost an hour after sunset. Jupiter rises now around midnight and Tuesday morning the moon and Jupiter rise together. Between 4:42am and 4:47am, International Space Station flies past the moon AND Jupiter. If the sky is clear, it will be a very cool sight! Stay up a few more minutes and see Saturn to the left of Jupiter.

Extraterrestrials On Earth?

Two researchers suggest a small amount of Earth's heaviest elements were created in the collision of two neutron stars 4.6 billion years ago. We probably have some of this in our bodies right now! Gold, platinum, uranium, even iodine might've come from such a collision, 100 million years before the formation of Earth and about 100 light years away from the gas clouds that formed our solar system. Speaking of colliding neutron stars, the Laser Interferometer Gravitational Wave Observatory and the European VIRGO detector have identified two new neutron star collisions 500 million light years away and 1.2 billion light years away. In total, since making history with the first-ever direct detection of gravitational waves in 2015, the network has spotted evidence for two neutron star mergers, 13 black hole mergers, and one possible black hole-neutron star merger. The first Planetarium opened in Chicago in 1930 on May 12th; The Fels Planetarium in Philadelphia was the second, opening in 1934. Turning to highlights in the night sky this week: Mars can still be spotted in the evening, Jupiter rising around midnight.


The InSight Lander Seismometer Detects a likely Mars Quake – recorded early last month a 40-second long low rumble was detected by seismic sensors placed on the surface to determine if and to what degree Mars is seismically active. The duration wasn't long enough to determine much about Martian tectonic activity, but still offered evidence that the interior of the red planet contimues to cool. A giant asteroid smashed into Earth 66 million years ago off the coast of what's now Mexico. Set off by the impact, an immense earthquake equivalent to a magnitude 10 or even 11.5 sent seismic waves pulsing through Earth's crust, according to researchers reporting online in the Proceedings of the National Academy of Sciences.At least 75 percent of species, including all nonbird dinosaurs, died out. Tiny traces of the Chixulub Meteor Impact Event appear to be preserved in a meter-thick layer of rock in southwestern North Dakota. The site, found in the Hell Creek Formation and dubbed Tanis, represents a unique snapshot of what happened on land in the immediate aftermath of the impact, says paleontologist Robert DePalma of the University of Kansas in Lawrence. But it's not the only plausible sequence of events that could have happened," Whiteside says. And there may be no way to know for sure if the scenario is the right one, or exact timing of the seismic waves' arrival, because there are so many unknowns about the lay of the land 66 million years ago. The 2019 Philadelphia Science Festival comes to a conclusion today with a celebration along the Benjamin Franklin Parkway featuring more than 100 hands-on activities and demonstrations. Turning to dark sky highlights: Mars is still visible in the west after sunset, Jupiter well up in the east by midnight; Venus, Saturn AND Jupiter can be seen in the pre-dawn sky between 5:00am and 5:45am.

Philadelphia Science Festival

The Philadelphia Science Festival encompasses nine days of more than 80 extraordinary, mostly free science events all around the city from the star party to the Carnival on May 4th on the Parkway. Sample informal and diverse science hands-on activities, lectures, debates and workshops. More information at Saturn's moon Titan is more like Earth than previously thought. It's small, it's cold and it's far, far away, but it has lakes of liquid methane and ethane(hydrocarbons) cold enough to be liquids rather than gases as they are here on Earth. Observations indicate some were so shallow that they evaporated during the transition from winter to spring on Titan and some may be 100 meters deep. It looks like the moon's subsoil has water-ice crystals bound into it, below the top eight inches. Meteor impacts kick up water molecules that can be detected by lunar orbiting satellites. It's not a lot of water, but scientists have been aware of some amount of water in the soil for some time. Turning to night sky highlights this week: The moon is visible in the pre-dawn sky with Jupiter, Saturn in the south and the last views of Venus low in the east. The next lunar cycle starts with New Moon next Saturday, May 4th.

Double Duty

NASA Astronaut Christina Koch's maiden voyage in space will extend for almost double the scheduled duration. She is now set to stay on International Space Station for a total of 328 days. This is the next step in the study of the effects of spaceflight on the human body and mind, and it's likely a result of the declaration of Vice President Mike Pence to return to the Moon by 2024. The Kepler-47 Twin Star-Twin Planet Solar System now shows another planet; Kepler 4d is 7 times larger than Earth with a 187-day year. The two stars orbit their common center of gravity every 7.5 days. The discovery drives two take-home messages: there's a tremendous diversity of planetary system configurations and our solar system is far from typical – most star systems in our Milky Way are binary star systems. Turning to the night sky highlights this week: Mars is visible in the west after sunset; the moon meets Jupiter Tuesday morning and Saturn Thursday morning one hour before sunrise. Venus and Mercury are low in the east at the same time.

Explorer of the Year

Next week, (Wednesday evening at the Union League in Philadelphia) the Geographical Society of Philadelphia will bestow its 128th Explorer of the Year honor – citing Derrick Pitts, Chief astronomer at the Franklin Institute and NASA Solar System Ambassador. Previous Society recipients including; Theodore Roosevelt, John Glenn, Diana Nyad, and last year's honoree, (photojournalist) Steve McCurry. The first ever image of a Black Hole confirms Einstein's suggestion that the event horizon should be visible. Subsequent images will provide more information; this was just the first! Think of it like viewing the first Hubble Space Telescope images ever and what the Hubble images look like now. Google Lunar Xprize Contender and Israel's first attempted lunar lander Beresheet crashed on the moon. SpaceIL is committed to try again. Turning to the night sky; Mars is still holding on in the west after sunset; Jupiter and Saturn are now due South at 4:30am, with Venus and mercury low in the east. They will look beautiful in the brightening morning twilight as sunrise now comes at around 6:30am.

Imaging The Unimaginable

The Event Horizon Telescope team may reveal an image of a black hole event horizon on Wednesday. An array of eight radio telescopes around the world will synthesize their observations of the accretion disk and the edge of the event horizon of Sag A – a massive black hole at the core of the Milky Way, as well as the black hole at the core of M87. This would be the first time an event horizon has actually been seen. Would allow study of the general relativity of the strong field regime, accretion and outflows near the edge of the black hole, and studies of event horizons in general. The plan is to use radio data to silhouette the black hole against the background of radio illumination of the accretion disk. Israel's first Lunar Mission SpaceIL Beresheet, now in orbit around the moon, is due to land next Thursday on the near side in the Sea of Serenity. If successful, it'll be the first privately funded spacecraft to reach the moon. Beresheet launched to the moon on Feb 21 at a cost of a mere $100 million. The Franklin Institute Science Awards Program takes place next week, honoring seven science and one business achievement. With clear dark skies, Mars and the moon are visible Monday evening in the west. Jupiter is now rising at midnight in the east, up with Saturn at 4:30 am.

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