Heads UP! for July 2020

Short version: Jupiter and Saturn peek over the horizon after sunset.  Earth is closest to them this month.  A nearly invisible lunar eclipse occurs the night of July 4/5.  Mars gets closer each week. Crescent Venus is at it’s brightest low in the dawn sky.  Mercury is in the morning sky later in the month, even lower than Venus.

Opening Act

The earlier time of sunset opens the curtain a bit wider on sights in the Summer sky. The first new players are Jupiter and Saturn.  The pair rise around sunset and remain low in the southern sky all summer. They look like a set of mismatched eyes staring at you as they clear the horizon about 8:30pm local daylight time; 7:30 by the end of the month. Jupiter and Saturn are largest and brightest at opposition on the 14th (magnitude -2.8) and 20th (+0.1), respectively. 

Tricks with Rings

Saturn’s rings show the ”opposition effect” and shine a bit brighter around the days when we line up between the Sun and Saturn on the 20th.  How many of Saturn’s moons can you spot? Can you set a personal record for number of outer planet moons you can find – Saturn plus four from Jupiter?  Iapetus brightens up south of Saturn by the last week of July.  Even when my eyes can’t see the Cassini Division very well, I can see the A (outer) and B (inner) sets of rings have slightly different shadings of white and off-white. Large telescopes may afford a view of the thinner C ring, closer to the planet.

Guest Appearances by Comets?

The past few months, we’ve been eagerly awaiting great comets that turned into crumbs. What about July? Some other comets have been reported to be in the range of smaller telescopes. Have you seen them? The much-searched-for 2017 T2 PanSTARRS will stay well placed high in the evening sky. Use large aperture binoculars, or a wide field telescope, and test your skill at following directions.

2020 F3 NEOWISE sounds like a character in a computer science fiction movie. It’s bright now, but behind the Sun from Earth’s point of view. It was readily seen in the SOHO C3 field last week. Based on sky charts I’ve seen, it will be very low in the morning sky, in Auriga, just after its July 3rd perihelion.  The best bet for seeing it will be mid-July in the evening sky as it fades through 4th magnitude. Get a finder chart and look for NEOWISE in binoculars. It’s closest to Earth on the 22nd, but not very close at 63 million miles away.  

C/2019 U6 Lemmon is moving into sight for our latitudes in mid-July. It may have already peaked at 6th magnitude, but stay tuned for updates.

The Long Twilight Skies are Great for Seeing Satellites

The International Space Station is visible multiple times throughout the night (like it was back in May) from the 13th through the 18th. Hosting 3 to 6 astronauts, it’s visible in the morning sky through the 11th.  Then, the ISS is visible in the evening for the rest of July.

If you haven’t seen a train of Starlink satellites moving across the sky, watch for a set after the next launch as they move toward their final, higher orbit where they will be much dimmer. Heavens-above.com gives train arrival times.

So Far Away

Celebrate the Fourth of July with the Earth at aphelion (its farthest point from the Sun) on Saturday morning.

A Very Faint Lunar Eclipse

The night of the 4th/5th, we’ll have a very light shading on the northern part of the Moon, darkest about 12:30am local daylight time.  This penumbral eclipse of the Moon covers only one-third of the Moon.  None of the darker umbral shadow we know so well will cross the Moon this time, as the Sun is only partially blocked from anywhere on the Moon.

November 30th’s penumbral lunar eclipse will have the entire penumbral shadow on the Moon, but also none of the umbra.  Can we take umbrage at this state of affairs?

Lunar perigee is the night of the 24th/25th, when we’ll have a crescent Moon visible after sunset.

Mars Attack

The Moon pairs up with Mars on the 11th and 12th.  Mars looks like it’s hurtling toward Earth, getting noticeably larger each month.  While it’s still as tiny as a lunar crater in the telescope, it’s time to start checking out the planet’s dusky markings. The South Pole is tilted toward Earth, where it’s late autumn.   

Venus Sparkles Mercury Twinkles

Trailing far behind the other planets in the morning sky, Venus is brightest at magnitude -4.5 on the 8th. It’s a beautiful waxing crescent in a telescope, appearing smaller each week as it extends its lead from the Sun.  The Moon won’t pass as close to Venus as it was last month, but they make a great pair on the 17th.  Mercury is still kicking around (or being kicked around) among the legs of Gemini.  The swiftest planet peeks into the morning sky for the last two weeks of the month.

Where is the Milky Way?

The band of thousands of stars in our galaxy arcs highest across the Summer night sky about 2am local daylight time.  

Sahara Dust UPdate Mon Jun 22 2020

Visibility is down to five miles at the San Juan International Airport.

Here’s a fantastic view of the dust from the visible-light satellite photo.

See the dust, shown as the light tan shading over the Caribbean and next to Africa.
The dust may come to the United States and Mexico this week. Click to see the latest loop.

See the previous post for links to various web sites.

Sahara Dust in Puerto Rico – Week of June 21st, 2020

A major dust storm is in progress for Puerto Rico and the surrounding islands in the Greater and Lesser Antilles. Concentrations of up to 600 ug/m3 at the surface are forecast by the US Navy dust model. While it’s unlikely concentrations this high will be observed, note that the US EPA Air Quality Index lists concentrations over 425 ug/m3 as hazardous to human health.

Visibility has decreased to six miles at the San Juan airport as of 10pm Atlantic Standard Time. The National Weather Service forecast discussion has information on what their meteorologists are thinking about this event:

SYNOPSIS...A very substantial Saharan dust plume will be over the area through at least the first half of the work week. Very hazy conditions and above normal temperatures can be expected. Shower activity is also expected to be very limited with of most of the area remaining dry. An active tropical wave may impact the area by the end of the work week.
4pm AST Sunday, June 21st. 

Re: National Weather Service Map Discussion – look esp. in aviation section: https://forecast.weather.gov/product.php?site=sju&product=AFD&issuedby=sju

Saharan Dust can reduce visibility (as is it today in San Juan, Puerto Rico), and at high concentrations cause health effects and hinder coral growth. The stable, dusty air also suppresses hurricane formation.

Dust from the Sahara can travel into the southeastern United States and Texas. Analysis of data from air pollution samplers have identified dust from the Sahara even in New Jersey, on rare occasions.

The US Navy is very concerned about dust in the ocean air – I assume because it makes it easier for enemies to hide.  So they’ve done a lot of work on Saharan Dust and other aerosols that reduce visibility.

Links to the most recent data:

Movie:  Satellite data process to show stable air coming from the Sahara Desert: http://tropic.ssec.wisc.edu/real-time/sal/splitE/movies/splitE5.html

Article from last week with satellite photos: https://www.nesdis.noaa.gov/content/noaa-satellite-tracking-dust-and-sand-being-blown-sahara-desert

EQB public Air Quality Index site appears not to be working, as it’s been out of commission since the hurricanes and earthquakes: http://www.prtc.net/~jcaaqs/Index.html

Naval Research Laboratory site: http://www.nrlmry.navy.mil/aerosol/

Click on NAPPS –> current –>tropical Atlantic or forecast loop

Composite NRL satellite data summary:

http://www.nrlmry.navy.mil/aerosol/globaer/ops_01/pride_composite/latest.html

NRL web site for aerosol measurements via solar irradiance:

http://www.nrlmry.navy.mil/aerosol/aeronet/carib/locator.html

Measured aerosols via solar irradiance: http://aeronet.gsfc.nasa.gov/new_web/aerosols.html (Harder to use!)

The Montserrat Volcano has been quiet lately, but just in case: Montserrat Volcanic Observatory: http://www.mvo.ms/

Satellite Observations of Volcanic Ash: http://www.ssd.noaa.gov/VAAC/messages.html

Trajectories web site (READY) http://www.arl.noaa.gov/ready/hysplit4.html

TOMS Satellite aerosol site: (inactive)
http://jwocky.gsfc.nasa.gov/

Science articles:

https://weather.com/science/weather-explainers/news/saharan-air-layer-african-dust-atlantic-basin

https://weather.com/science/weather-explainers/news/saharan-dust-africa-caribbean-gulf-of-mexico

Links to other maps:

Plots of satellite detection of dust: ftp://toms.gsfc.nasa.gov/pub/omi/images/aerosol/Y2018/IM_aersl_omi_20180609.png

Other computer forecasts of dust concentrations: http://forecast.uoa.gr/LINKS/DUST/dust.php?field=dconc&lan=en

Today’s Temperature Inversion

Okay, weather fans, I’d like to misuse a meteorological term today!

A temperature inversion is when air temperature increases with height, rather than decreasing with altitude. It’s why we’ve been hearing cars racing up and down the parkways miles away from us here in Westchester County during the evenings through mid-morning. The sound is bent toward the ground, so it’s trapped in the stable layer of air, more concentrated and thus, louder than sound that has more vertical spread. So far, so good.

But I’d like to use temperature inversion in a different way. Usually, temperatures are cooler as we go north. Right? It’s generally cooler in Maine than in Washington, DC. And, it has been as the winds have brought and kept cooler air over the northeastern United States. Today we invert that temperature paradigm. The multiple days of strong summer sun is warming the ground. Here’s the forecast map for maximum temperature for today, July 17, 2020:

This is because of clouds in from Philadelphia southward. There’s an upper air storm pulling moisture into the Carolinas and Virginia. It makes a gray line on the forecast map like a curtain descending over the area.

5pm Wednesday, July 17th, forecast percent cloudiness. Which side of the line will you be on?
Combined visible/infrared satellite view for 7am, Wednesday, June 17th. Look at the shadows of the towering clouds on the ground and lower cloud decks. 3D view without the 3D viewer! The ground background during daylight is real, at night it’s a digital background, including city lights. The circular cloud bands over North Carolina is where the upper air storm is located.
Map of winds and moisture at 850millibars pressure (about 5,000 feet above the ground). Shows the storm over the Carolinas pulling in moisture.

The moisture over Virginia will move northward into this weekend with a great chance of shower and, ironically, warmer temperatures for the mid-atlantic states.

Venus in the Daytime Morning Sky

Viewing Venus in daylight, near the Sun, is a tricky and potentially dangerous affair.  I like to catch the Evening Star in daytime because it follows the Sun in the sky.* 

But Venus has been rocketing out of solar conjunction, becoming the Morning Star.  On June 3rd, Venus was ½ degree above the Sun. Today, it is 20 degrees out from the Sun – that’s two fist-widths held at arm’s length.  So it was easy to block the Sun behind my roof eaves and be confident, let vigilant, that the Sun wouldn’t sneak into my optical tube.  That would cause melting of the optics and blindness.  Also, in the morning, Venus is to the upper right of the Sun, so I can look over the object I have blocking the Sun. 

This morning about 10am Local Daylight Time, that’s what I did.

I used my iPhone Planet Finder** app to get Venus’ altitude above the horizon and my trusty electronic saw-blade angle finder to point my dob to the correct angle and then swept from side to side at that angle.  I found Venus in my 9×60 finder scope.  It was big and bright in the blue sky.  I used the waning crescent Moon earlier to get the telescope to focus properly.

Here’s the photos.

Photo from Canon XS at prime focus of Orion 200mm dobsonian reflecting telescope. ISO 200 for 1/100 second. I used two barlow lenses in succession to magnify Venus’ image. No cropping, enlargement or processing.
Moon. Also Canon XS through the dob. 1/250 second exposure at ISO 200. Only one barlow used, to reach focus while using the dob as a telephoto lens.

* My Orion Dob just goes up and down and back and forth and doesn’t have a motor to track objects in the sky. To track a celestial object, it helps to have a motor and computer for altitude/azimuth telescopes like mine and a motor pushing the telescope while it rotates around the telescope’s axis that points to Polaris, the (almost) stationary North Star. Or, like me, you have to bump it up a bit and over to the right a bit as the Earth turns. (As I say at star parties, “Not your fault you lost Jupiter in the eyepiece, it’s that #*%$@! Earth’s rotation again.”)

* * You can use any astronomy app to find the planet’s altitude and azimuth.  The Planet Finder app was handy today.  See photo.  

Wiley angle finder attaches with magnets to the tube of my telescope. Note 57.2 degree angle and Planet Finder prediction of 57.7 degrees above the horizon. (Venus was centered in the scope at the time.)

Historical notes: Apparently on November 3rd, 2010, I viewed Venus nine degrees above and to the right of the Sun in the morning daytime sky. Once, and I can’t find the reference, I used a street sign to block the Sun and saw Venus nine degrees directly above the Sun with binoculars and with my telephoto lens on my camera. Venus was at superior conjunction (Venus behind the Sun, small but fully lit. ). Don’t try this at home or anywhere else!

Find Comet PanSTARRS, Nicely Framed, If You Can

Once again, astrobob from Duluth, Wisconsin, (not related to me) has a wonderful set of directions for a fainter object. Comet PanSTARRS (C/2017 T2) is nicely framed by the bowl of the Big Dipper asterism. It’s magnitude 8 or fainter, and we’ll need at least 50mm binoculars or a telescope. The wider the view the better.

View of the sky from the bowl of the Big Dipper (at top) down to the Sun and Venus below the horizon. About 10:30pm local daylight time at 40 degrees north.

Here’s some photos I took last night about 10:30pm EDT. I didn’t use my tracker, but the Dipper is near enough to the North Celestial Pole to reduce the motion of the stars in the sky. In any case, lingering twilight and light pollution made longer exposures very foggy. There were some thin cirrus clouds visible earlier and they may have hung around. Cirrus often are not visible to the unaided eye at night. A fellow meteorology student at Rutgers used to call this phenomenon ‘cirrus disappearus’. But, they are often still there. I noted some fuzziness around the brighter stars that might be from the cirrus. That may be the reason for the fogginess of the longer exposures. Comets, being fuzzy themselves, can hide very nicely as they blend in with high clouds.

Take a look up for yourself tonight or a soon as possible. Skies should be clear until at least 11pm EDT in the mid-Atlantic states of the United States down into the Carolinas.

Let me know what you see!

Each of the photos are my Canon XS on a tripod, at ISO1600, the camera’s top setting. I often don’t go to 1600 because of the noise that shows up from the heat in the camera, but it was in the 60s last night, so the camera stayed cool. The camera also has noise reduction for long exposures. I used a focal length of f/2.0, not the widest setting, but a setting a step or two above the widest can help make a sharper photo.

Six-second exposure.
Ten-second exposure.
Thirty-second exposure. Light pollution or high clouds can overwhelm stars in longer exposures.


Heads UP! for June 2020

Short Version:

To make the most of our short summer nights, we’ll have to deal with all the bright planets except Mercury up during the morning hours. Jupiter and Saturn will eventually rise late in the evening as they approach their July oppositions. Mars will be found higher than J&S in the southeastern sky before dawn, when the gas giants are settling into the southwest. Venus flits to the morning sky. Mercury keeps its claim in the evening sky, low, but findable, below Castor and Pollux in the west-northwest. The Milky Way arcs overhead just before dawn. In the evening, the galaxy’s starry band may look like a hazy band in a dark eastern sky.

Go Gas Giants!

Jupiter and Saturn’s increasing size make for spectacular views in the telescope. The gas giants start out the month rising just before midnight Daylight Time, but rush to rising around 9:30pm by June’s end.  The duo of giants are placed nicely near each other, but they are in the lower third of the sky, highest during the wee hours of the morning. Jupiter’s moons should be visible in binoculars held up against a solid object. The Moon joins them on the 8th and 9th, first just to their west, then just to their east.

Jupiter’s moons occasionally transit the striped planet in pairs, making the view three dimensional. It’s best in larger telescopes.  Saturn and its rings are tilted 24 degrees toward us with its north pole visible. Titan, a moon with an atmosphere, is visible at 9th magnitude in small telescopes. With a larger, say, six-inch-or-greater scope, try to catch Iapetus is at its brightest early in the month to the west of Saturn, temporarily joining Dione, Tethys and Rhea near 10th magnitude. Iapetus passes north of Saturn on the 20th, dimming as it moves eastward.

Mars Coming Up

Mars is at a right angle to the Earth-Sun line – ‘quadrature’ on the 6th/7th. This view makes Mars look gibbous from Earth. Even a small telescope may show how out of round Mars is at 85 percent illuminated. Mars’s brightness passes into negative magnitude this month. As Mars’s size passes 10 arc seconds this month, you might start to see various shadings on its surface if you use a large telescope. For a view of an outer ice giant, use Mars to help find Neptune two degrees above it.  They are closest on the 13th

Venus Skips into the Sunrise

Shuttling past the Sun in our skies, Venus passes through inferior conjunction on the 3rd at 1:38pm EDT, just transiting across the Sun by a quarter of a degree. Venus squirts out into the morning sky at mid-month, surprisingly visible, even though it’s just 10 degrees above the horizon at sunrise.  By the end of the month it gets to that 10 degrees mark above the east-northeastern horizon during mid-twilight (about 4:30am EDT).  Venus appears so low, it’s hard to believe Venus rises almost two hours before the Sun.  Try to catch the Moon and Venus rising a Moon-width apart on the 19th.  Can you spot the Pleiades ten degrees above Venus in the second half of the month? Then try for the Hyades just below Venus. Use binoculars.

Mercury on its Own

Our inner-most planet must be wondering where the party went.  All alone with no other bright planets in the evening twilight, Mercury is farthest out from the Sun on the 3rd/4th. If you can spot Gemini’s Castor and Pollux in the west-northwestern sky, scan downward with binoculars to find Mercury.  It’ll be getting fainter and sets by 10pm Daylight Time. High power will show a waning crescent. Mercury passes through inferior conjunction, four degrees from the Sun, on the 30th.  Our Moon is closest to Mercury on the 22nd, hard to find only 13 degrees from the Sun. 

Another Ice Giant

How about Uranus? It’s a morning planet too, rising after Mars. The Moon passes half-a-fist-held-at-arm’s-length south of the ice giant on the 14th, with the Moon just past last quarter.

Our Moon

Perigee occurs June 2nd at 10:35pm, 2½ days before June 5th’s Full Moon, as the monthly date of closest approach to the Earth drifts away from the time of Full Moon. The Moon will be 90 percent full then.  This will be a great time to view its rugged south polar region as the Moon appears tipped five degrees toward Earth. There is a bonus lunar perigee for the month on the 30th, about 3,000 miles farther than the perigee on the 2nd.  The perigee on the 30th will be the farthest (least close) lunar perigee of the year.  (Take a minute or two to unwrap what that means. Or just jump to the next paragraph!) 

Summer!

Northern Hemisphere’s Summer Solstice occurs on the 20th at 5:45pm EDT. This year’s earliest sunrise is June 14th. By the end of June, it’ll be noticeably darker later in the morning, if you are up before sunrise.

ISS Sightings

The International Space Station has only a few overflights; early in June evenings and during morning twilight in late June.

Department of Things Unseeable

There is a penumbral lunar eclipse not visible from the United States on the 5th. If you were watching this from the Moon, the Sun would only be partially blocked by the Earth from your point of view.  An annular solar eclipse happens on the 21st, visible from parts of Africa and Asia. We’ll get our chance at a faint penumbral lunar eclipse on July 4/5.

Photo of the International Space Station’s Trail Across the Sky

I love an advertisement that pokes fun of the company it’s advertising.  Actually, I love funny ads in general!

One in particular.  The copy read, “Here’s a glorious, full-sized color photo of the Goodrich blimp!”  It was a photo of a (blank) blue sky.  Goodrich was a rubber tire company, but not the one (Goodyear) that had the blimps. 🙂

So, you know where this is going.  I kinda missed the ISS’s (ISS’?) overflight last night.  It’s hard to focus the camera without bright stars, there were too many streetlights, yada, yada, yada.

As I was focusing on the Big Dipper, I noticed the very bright dot of the ISS at the bottom of my frame.  Here is the photo:

Upside-down Big Dipper between a roof gutter and a tree.
The track of the ISS is that bright dash leaving the bottom of the photo.
Five-second exposure Canon XS 18mm zoom lens at f/4, ISO 800.
No processing.

The ISS, in the sunlight 432km right above me, was brilliant!

I re-aimed the camera and tried twice more, each with the two-second delay to decrease camera shake, and the same five-second exposure time. If I take a shorter exposure, the stars don’t show up, but the ISS makes a dot like it looks in the sky, not the streak we see in timed exposures.

Hope you had better luck! Share your story in the comments.

May 16 2020: Gulf of Mexico to Gulf of Maine International Space Station Overflight Tonight

The ISS will fly over the eastern United States during twilight tonight, crossing New Orleans, Washington (DC), New York and Boston. You’ll be able to see the ISS crossing directly overhead between 8:38pmCDT for New Orleans and other places in the Central Time Zone, 9:42pm EDT for the folks from Washington, DC and the Eastern Time Zone.

Map for the overflight, centered on Washington, DC, so you can see the path over the eastern United States.

Heavens-above.com forecast of ISS ground track for Saturday, May 16th.
Time hacks in eastern daylight time.
Example sky plot for ISS over Washington, DC.
This map will be similar for most locations near the ground track.
A couple of minutes earlier for locations to the southwest, later for places to the northeast.

For many locations, the track of the ISS through our skies will take it in front of the handle of the Big Dipper! The stars of the tail of the Great Bear may be hard to pick out of the bright twilight. I’ve found them easier to see after the ISS goes by, as the eye has something distant to focus on.

This fly-over is not a planned event specifically for the Eastern United States – it’s a consequence of orbital mechanics of the many loops the ISS takes around our planet.

Update! Mid-May 2020 Swan Song, ISS all-night, Venus/Mercury, Morning Planets

  • Summary:
  • Is Comet Swan going to re-brighten?. It’s low in the northeast just before sunrise. Also later in the month low in the northwest right after sunset.
  • This week, try for as many ISS overflights as you can see in a night – every 90 minutes or so for a few nights, then just in the evening sky. Check heavens-above.com or the NASA site for times.
  • Venus stands bright, but getting lower, in the west-northwest. Watch for Mercury’s pop-up appearance, arcing above Venus later next week. The very thin Moon joins them in twilight on the 24th/25th.
  • Jupiter and Saturn are still outstanding low in the southeastern sky before sunrise. Check out their moons! Mars socially distances to the left.

Comet SWAN: Another one falls to dust (I think there is a song there!). It may be showing signs of re-brightening. Best resource for SWAN is Astro Bob (no relation) at https://astrobob.areavoices.com/ .

ISS overflights! The night of the 15th /16th has as many as six (!) overflights, some better than others. Here’s a list from heavens-above.com for White Plains, NY. This is also a great night of ISS viewing for the northeast and middle-atlantic states of the USA. See heavens-above for times for your location. The ISS has a “high beta angle” near the summer solstice for the northern hemisphere. This year beta season is very early and here’s a link to why. Thanks to space station guys for the reference!

15 May-2.420:51:2310°S20:53:5420°SE20:56:2610°Evisible
15 May-2.822:27:1210°WSW22:30:2749°NNW22:33:4510°NEvisible
16 May-0.700:05:4010°NW00:07:5216°NNW00:10:0410°NNEvisible
16 May-0.501:43:4010°NNW01:45:4115°N01:47:4310°NEvisible
16 May-2.203:20:0110°NW03:23:1137°NNE03:26:2210°Evisible
16 May-2.804:56:5810°WNW04:59:5327°SW05:02:4810°SSEvisible
Times you can see the International Space Station from the NYC metro area.
Thanks to heavens-above.com !

The best overflight over NYC is on the 16th, overhead, across the Big Dipper, about 9:43pm. After the 19th, the overflights are after sunset through mid-night.

At Four-so-early-in-the-morning (Daylight Time), see the outer planets. (Pluto’s location marked for completeness. Not visible.)

4:30am Local Daylight Time sky May 16th. Good for rest of May
(However, the Moon will move on each day toward new moon on the 22nd.)

Cute break for today: When I wear my Planetary Society shirt, My two-year old grandchild points to the tiny dots at the bottom of the shirt, out beyond Neptune, and says “planets”. I guess she’s in favor of Kuiper-Belt objects as planets!