The United States Postal Service has issued a number of enticing forever stamps in recent years, and I’ve begun accumulating stamps faster than I use them. Sound familiar? If so, why not use them for extra postage items—even if you end up spending a little more than is required.
The current value of a forever stamp is 55¢. If you have a postal scale at home to weigh the envelopes you want to post, this handy guide will show you how many forever stamps to use for envelopes of different sizes and weights. (Mail within the U.S. only)
Standard Envelopes (≤11.5″ long, ≤6.125″ high, ≤0.25″ thick)
0 to 1 ounce: 1 forever stamp
1 to 4 ounces: 2 forever stamps
4 to 8 ounces: 3 forever stamps
Large Envelopes(11.5-15″ L, 6.125-12″ H, or 0.25-0.75″ T)
0 to 1 ounce: 2 forever stamps
1 to 4 ounces: 3 forever stamps
4 to 7 ounces: 4 forever stamps
7 to 9 ounces: 5 forever stamps
9 to 12 ounces: 6 forever stamps
12 to 15 ounces: 7 forever stamps
If you are mailing a standard envelope that has one or more of the characteristics in DMM 101.1.2, add an ounce to the measured weight to cover the non-machinable surcharge.
If you are mailing a large envelope that is rigid, is non-rectangular, or is not uniformly thick, then take your envelope to the post office to mail because you will have to pay parcel prices.
PIA11690: Global View of Iapetus’ Dichotomy, NASA/JPL/Space Science Institute
What a strange world Iapetus is! The third largest satellite of Saturn—and the outermost of Saturn’s large satellites—is a moon of many mysteries. We’ll take a look at three of them.
Mystery #1: Iapetus appears to be an original satellite of Saturn, and yet unlike the other regular satellites, its orbit is inclined 15.5˚ relative to Saturn’s equator. The reason for this steep inclination is not well understood.
And, oh, the view! Iapetus is the perfect perch to view Saturn’s rings, as it orbits Saturn every 79.3 days in its steeply inclined orbit.
Saturn from Iapetus at the highest point of its inclined orbit
Mystery #2: Iapetus has the largest albedo dichotomy in the solar system. Why? Iapetus is locked in synchronous rotation as it orbits around Saturn, with the leading hemisphere ten times darker than its trailing hemisphere.
Iapetus has an average visual magnitude of 10.2 west of Saturn and 11.9 east of Saturn. Its albedo ranges from 0.5 to 0.05. (Diagram not to scale)Bright and dark material on Iapetus. The 500-km-wide crater Engelier is at bottom.
It is thought that the natural state of the Iapetian surface is the bright icy part, with the dark material a thin veneer, less than a meter thick.
Mystery #3: Iapetus has a shape consistent with a body spinning every ~16 hours and yet its rotation period is 79.3 days, and it has a prominent ridge that can be followed 3/4 of the way around the equator.
Walnut-shaped Iapetus with its prominent equatorial ridgeIapetus’ equator-girdling ridge, up to 20 km high, is heavily cratered and therefore ancient
The surface of Iapetus is heavily cratered, indicating it is very old. Could two comparable-sized objects have collided almost head-on billions of years ago to form Iapetus?
Mountainous terrain along Iapetus’ equatorial ridge imaged by the Cassini spacecraft during its closest flyby on September 10, 2007
As beautiful as spacecraft flyby and orbital images are of Iapetus and the many other interesting moons in our solar system, can you imagine what vistas await us once we start exploring their surfaces with rovers? Anticipation of these images and scientific discoveries surely is an impetus to explore the surface of Iapetus (and other moons) sooner rather than later.
Dark and light material on Iapetus was imaged up close by the Cassini spacecraft during its September 10, 2007 flyby.Sizes of Iapetus, Earth’s moon, and Earth compared
References
Bonnefoy, Léa E., Jean-François Lestrade, Emmanuel Lellouch, Alice Le Gall, Cédric Leyrat, Nicolas Ponthieu, and Bilal Ladjelate. “Probing the subsurface of the two faces of Iapetus.” arXiv preprint arXiv:1911.03394 (2019).
Leleu, Adrien, Martin Jutzi, and Martin Rubin. “The peculiar shapes of Saturn’s small inner moons as evidence of mergers of similar-sized moonlets.” Nature astronomy 2, no. 7 (2018): 555-561.
Rivera-Valentin, Edgard G., Amy C. Barr, EJ Lopez Garcia, Michelle R. Kirchoff, and Paul M. Schenk. “Constraints on planetesimal disk mass from the cratering record and equatorial ridge on Iapetus.” The Astrophysical Journal 792, no. 2 (2014): 127.
Climate change is a serious problem requiring immediate attention. We need to reduce greenhouse gas emissions into our atmosphere as fast as possible. Half measures will not do. We are rapidly running out of time before the quality of life for all humans on planet Earth declines, especially for the economically disadvantaged.
A precipitous decline in biological diversity due to habitat loss and extinction of species is of even greater concern, and yet it gets very little attention in the mainstream media. While climate change will render large areas of the Earth uninhabitable, biodiversity loss will lead to a partial or complete collapse of the ecosystem humans depend upon for food.
Getting even less attention is the cause of both of these problems: overpopulation. If you were born in 1976, the world’s human population is now twice what it was then. If you were born in 1955, there are three times as many people alive now than there were then. We have a climate emergency and a biodiversity emergency because we have a population emergency. The number of humans on this planet needs to decline, and the only humane way to accomplish that is to have fewer children. It is that simple.
And, yet, we often see this or that news article lamenting the fact that the birth rate in this or that country is too low. That’s crazy! A low birth rate should be a cause for celebration given the current state of the world and its environment. Certainly, a low birth rate does lead to some economic challenges, but these pale in comparison to the challenges we will face if population (and consumption) continue to grow.
As a humanist, I believe that we should do all we can to alleviate and eliminate human suffering. It is our highest moral calling. To be sure, some human suffering is inevitable and necessary when an individual makes poor decisions and suffers the consequences before hopefully making a mid-course correction. But the kind of suffering I am talking about is suffering that is imposed upon a person through no fault of their own, be it the cruelty of other human beings, or the cruelty of nature.
In this light we can see that our economic systems, governments, and most religions are utterly failing us. Nothing short of drastic changes will solve these problems. May wisdom, intelligence, ingenuity, and compassion guide us, rather than fear, ignorance, hatred, and dogma.
There are two organizations dedicated to stabilizing human population throughout the world by lowering the birth rate: Population Connection and Population Balance. I encourage you to support their work as I do.
In the table below, you will find the world population for each year 1950-2025. The growth factor tells you how much the population has grown between a given year and the latest year, For example, you will see that the world population in 2025 is twice what it was in 1976, and three times what it was in 1955.
Edmund Weiss (1837-1917) and many astronomers since have called asteroids “vermin of the sky”, but on October 4, 1957 another “species” of sky vermin made its debut: artificial satellites. In the process of video recording stars for possible asteroid occultations, I frequently see satellites passing through my 17 × 11 arcminute field of view.
I’ve put together a video montage of satellites I serendipitously recorded between August 9, 2019 and December 22, 2019. Many of the satellite crossings are moving across the fields as “dashes” because of the longer integration times I need to use for some of my asteroid occultation work. A table of these events is shown below the video. The range is the distance between observer and satellite at the time of observation. North is up and east is to the left.
Satellites in higher orbits take longer to cross the field. In the next video, the originally geosynchronous satellite OPS 1570 (IMEWS-3, “Integrated Missile Early Warning System”) is barely visible until it exhibits an amazing sunglint around 3:41:22 UT.
I caught one meteor on October 6, 2019 at 9:57:43 UT. Field location was UCAC4 515-043597. The meteor was a Daytime Sextantid, as determined using the method I described previously in There’s a Meteor in My Image. The meteor even left a brief afterglow—a meteor train!
References Hughes, D. W. & Marsden, B. G. 2007, J. Astron. Hist. Heritage, 10, 21
Musical mystery, or compositional coincidence? Wolfgang Amadeus Mozart wrote the music for his one-act opera Bastien and Bastienne in 1768, at the age of 12. The short Overture to Bastien and Bastienne bears a remarkable resemblance to the opening theme of Beethoven’s Eroica symphony, composed between 1802 and 1804. Although the keys are different (Mozart’s overture is in G major and Beethoven’s symphony is in E♭ major), could it be that Beethoven had Mozart’s theme in mind while he composed his 3rd symphony? It is unlikely that Bastien and Bastienne was known to Beethoven, as that music received its first public performance in 1890. Perhaps, just a coincidence. Great minds think alike, it appears.
Overture to Bastien and Bastienne, Statatskapelle Dresden, Sir Colin Davis, RCA 74321-56698-2 Symphony No. 3, “Eroica”, Chicago Symphony Orchestra, Sir Georg Solti, London 430 792-2
Are any of you nearing retirement (as I am) or already retired who might be interested in moving to an astronomy-oriented retirement community? If you are, I encourage you to join the moderated Groups.io discussion group Dark-Sky Communities at
I am working to establish such a community and would value your input and assistance. That work involves extensive research, networking, writing articles in various publications to reach a wider audience, finding a suitable developer, and seeking benefactors.
Some characteristics of the community I envision include:
Rural location with a dark night sky, but not too far from a city with decent medical facilities, preferably to the northeast or northwest;
Location with an abundance of clear nights and mild winters, probably in Arizona, New Mexico, or West Texas;
Lighting within the community that does not interfere with astronomical activities, strictly enforced;
Community is owned and operated by a benefit corporation or cooperative that will rent a house or apartment to each resident;
Observatories will be available for rental by interested residents who will equip them;
Pro-am collaborative research opportunities will be developed and nurtured;
A community observatory and a public observatory for astronomy outreach will be constructed and maintained;
Lodging will be available for visitors and guests;
There will be opportunities for on-site income operating and maintaining the community or, alternatively, a reduction in monthly rental fees.
Many of us have spent a significant amount of time and energy over the years trying to rein in light pollution in our respective communities and in the wider world, with varying degrees of success. Those efforts should continue, but the grim reality is that light pollution is continuing to get worse almost everywhere.
The opportunity to live in a community of varied interests but with a common appreciation for the night sky and a natural nighttime environment will appeal to many of us. Furthermore, a dark-sky community will afford us opportunities to show the world at large a better way to live.
Traditionally, in the United States at least, if one wants to live under a dark and starry night sky, your only options are to purchase land and build a house on it, or purchase an existing rural home. Not only is buying and maintaining rural real estate unaffordable or impractical for many, many would prefer to live in a rural community, provided that the night sky and nighttime environment are vigorously protected. Rental will also make it easier to move into and out of the community as circumstances change.
In 2020, the best dates and times for observing the zodiacal light are listed in the calendar below. The sky must be very clear with little or no light pollution. The specific times listed are for Dodgeville, Wisconsin (42° 58′ N, 90° 08′ W).
Here’s a nicely-formatted printable PDF file of the zodiacal light calendar:
The best nights to observe the zodiacal light at mid-northern latitudes occur when the ecliptic plane intersects the horizon at an angle of 60° or steeper. The dates above were chosen on that basis, with the Sun at least 18° below the horizon and the Moon below the horizon being used to calculate the times. An interval of time of one hour either before morning twilight or after evening twilight was chosen arbitrarily because it is the “best one hour” for observing the zodiacal light. The zodiacal light cone will be brightest and will reach highest above the horizon when the Sun is 18° below the horizon (astronomical twilight), but no less.
If you are interested in calculating the angle the ecliptic makes with your horizon for any date and time, you can use the following formula:
where I is the angle between the ecliptic and the horizon, ε is the obliquity of the ecliptic, φ is the latitude of the observer, and θ is the local sidereal time (the right ascension of objects on the observer's meridian at the time of observation).
Here’s a SAS program I wrote to do these calculations:
Each meteor shower is identified using its three-character IAU meteor shower code. Codes are bold on the date of maximum, and one day either side of maximum.
Here’s a printable PDF file of the meteor shower calendar shown below:
In terms of bulk properties, Venus is the most Earthlike planet in the solar system. The diameter of Venus is 95% of Earth’s diameter. The mass of Venus is 82% of Earth’s mass. It has a nearly identical composition.
But…the average surface temperature of Venus is 735 K (863˚ F) and the surface atmospheric pressure is 91 times greater than Earth’s—equivalent to the pressure 3,000 ft. below the ocean’s surface. The present atmosphere of Venus is composed of 96.5% carbon dioxide (CO2) and 3.5% nitrogen (N2), plus a number of trace elements and compounds.
Venus was not always so inhospitable. What happened?
The cratering record suggests that nearly all of Venus has been resurfaced within the last 300 – 800 Myr. Before that, Venus probably was much more hospitable, even habitable, perhaps. The Pioneer Venus large probe and infrared spectral observations from Earth of H2O and HDO (deuterated isotope of water) indicate that the deuterium-to-hydrogen ratio in the Venusian atmosphere is 120 – 157 times higher than in water on Earth, strongly suggesting that Venus was once much wetter than it is today and that it has lost much of the water it once had to space. (Hydrogen is lighter than deuterium and therefore more easily escapes to space.) In addition to deuterium abundance, measuring the isotopic abundance ratios of the noble gases krypton and xenon would help us better understand the water history of Venus. These cannot be measured remotely and requires at-Venus sampling.
Venus receives 1.92 times as much solar radiation as the Earth, and this was undoubtedly a catalyst for the runaway greenhouse effect that transformed the Venusian climate millions of years ago.
We know that CO2 is a potent greenhouse gas, but anything that increases the amount of water vapor (H2O) in the atmosphere leads to global warming as well. As do clouds.
Climate modeling shows us that that the hothouse on the surface of Venus today is due to CO2 (66.6%), the continual cloud cover (22.5%), and what little water vapor remains in the atmosphere (10.9%).
Interestingly, if all the CO2 and N2 in the Earth’s crust were somehow liberated into the atmosphere, our planet would have an atmosphere very similar to Venus.
Venus is the easiest planet to get to from Earth, requiring the least amount of rocket fuel. There is so much we still don’t understand about how Venus transformed into a hellish world, and we would be well-advised to learn more about Venus because it may inform us about Earth’s future as well.
Tessera terrain covers about 7% of the surface of Venus. These highly deformed landforms, perhaps unique in the solar system, may allow us to someday sample the only materials that existed prior to the great resurfacing event.
COLORIZED TOPOGRAPHIC DATA OVERLAID UPON FORTUNA TESSERA TERRAIN IMAGE In this radar image, blue represents the lowest elevations, white the intermediate elevations, and red the highest elevations. Source: Emily Lakdawalla, https://www.planetary.org/blogs/emily-lakdawalla/2013/02071317-venus-tessera.html .
If living organisms ever developed on Venus, the only place they could still survive today is 30 miles or so above the surface where the atmospheric temperature and pressure are similar to the surface of the Earth.
Even four billion years ago, Venus may have been too close to the Sun for life to develop, but if it did, Venus probably remained habitable up to at least 715 Myr ago.
Now for the bad news. All main-sequence stars, including our Sun, slowly brighten as they age, and their habitable zones move outward from their original locations. Our brightening Sun will eventually render the Earth uninhabitable, certainly within the next two billion years, and our water could be lost to the atmosphere and then space within the next 13o million years, leading to a thermal runaway event and an environment similar to that of Venus. Human-induced climate change could make the Earth uninhabitable for humans and many other species long before that.
One indication that water is being lost to space and surface warming is occurring is water vapor in the stratosphere. The more water vapor that is in the stratosphere, the more water is being forever lost to space and the greater the surface warming. Careful and continuous monitoring of water vapor levels in the Earth’s stratosphere is important to our understanding of climate change on Earth.
To conclude, Arney and Kane write:
“Venus teaches us that habitability is not a static state that planets remain in throughout their entire lives. Habitability can be lost, and the runaway greenhouse is the final resting place of once watery worlds.”
References
Arney, G., & Kane, S. 2018, arXiv e-prints, arXiv: 1804.05889
Bézard, B., & de Bergh, C. 2007, J. Geophys. Res., 112, E04S07, doi: 10.1029/2006JE002794.
Ostberg, C., & Kane, S. R. 2019, arXiv e-prints,arXiv: 1909.07456
The average adult weighs 15 pounds more than 20 years ago
40% of adults and 20% of children are obese
The average adult is eating ~300 calories more per day than in the 1970s
Beginning in 2015, more money is spent eating out than eating at home
Restaurant portion sizes have quadrupled since the 1950s
It’s true, we’re eating away from home more often, and the portion sizes we’re being served at restaurants are usually larger than they need to be. Have you ever had a totally satisfying meal at a restaurant that doesn’t leave you feeling like a beached whale afterwards? A well-prepared and well-presented meal does not have to be large to be loved.
Large portion sizes at restaurants are particularly a problem for those of us who are conditioned to eat everything on our plate, and who don’t like to take leftovers home.
Restauranteurs, please step up to the plate and fight obesity by making your standard portion sizes smaller. If a customer wants a larger portion, they should have to ask for it.
References
Briefing: The obesity epidemic. (October 18, 2019). The Week, 19(946), 12.
