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Why aren’t day and night equal on the day of the equinox?

Image via Wikipedia

Image via Wikipedia

For North American time zones, the 2014 autumnal equinox will come on Monday, September 22 at 10:29 p.m. EDT, 9:29 p.m. CDT, 8:29 p.m. MDT or 7:29 p.m. PDT. This equinox falls on Tuesday, September 23 at 2:29 UTC.

Twice a year – on the March and September equinoxes – everyone worldwide supposedly receives 12 hours of day and 12 hours of night. Yet, in actuality, there is more daylight than nighttime on the day of the equinox. Why?

Mercury’s September 2014 apparition favors Southern Hemisphere


Mercury, the innermost planet of the solar system, swings to its greatest evening elongation (26o east of the setting sun) on September 21, 2014. Then, in a little more than one day thereafter, it’ll be the September equinox. So in September 2014, Mercury’s greatest evening elongation pretty much comes concurrently with the September equinox.

The most favorable time to see Mercury in the evening sky is when this planet’s greatest eastern (evening) elongation closely coincides with the spring equinox. Because the September equinox is the Southern Hemisphere’s spring equinox, southerly latitudes get to see a wonderful evening apparition of Mercury throughout the month of September. However, in the Northern Hemisphere, the September equinox is the autumn equinox. Unfortunately, Mercury’s presence in the evening sky is most subdued when its greatest evening elongation happens in close conjunction with the autumn equinox. That’s why the Southern Hemisphere has it over the Northern Hemisphere for this particular evening apparition of Mercury.

Supermassive black hole in a galaxy only 300 light-years wide

Artist's concept of the supermassive black hole in the tiny galaxy M60-UCD1.

Artist’s concept of the supermassive black hole in the tiny galaxy M60-UCD1.

Our Milky Way galaxy is thought to be about 100,000 light-years wide. The black hole at the center of our galaxy is thought to be as massive as 4.1 million of our suns. Now imagine a black hole five times the mass of our Milky Way’s central black hole, inside a galaxy only 300 light-years across. That’s the situation inside the dwarf galaxy M60-UCD1, whose diameter is only 1/500th that of our Milky Way.

June through August 2014 hottest ever recorded globally

Image Credit: NOAA/NCDC

August 2014 temperature departures across the globe. It was the warmest August since record keeping began in 1880. Image via NOAA/NCDC

The results are in for NOAA, and they show that the combined average temperature for global land and ocean surfaces for August 2014 was a record high, beating out the old record set back in 1998. The June through August global land and ocean surface temperatures were 0.71°C (1.28°F) higher than the 20th century average, making it the warmest such period since record keeping began in 1880. Have you heard the argument that the past 15 years haven’t seen much warming? Those using that argument are – knowingly or unknowingly – dating it back to the extremely warm year of 1998, when an unusually strong El Niño formed. While we haven’t seen as big of a spike in heating as in 1998, the globe continues to warm and records continue to be broken.

Space-based particle detector hints at dark matter

The Alpha Magnetic Spectrometer (AMS-02) experiment is a state-of-the-art particle physics detector that is constructed, tested and operated by an international team composed of 60 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. It is attached to the International Space Station and has been in operation since 2011.  Image via NASA

The hint of dark matter came from this instrument, the Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station. Image via NASA

One of the great discoveries of the coming century will be the direct detection of dark matter. This mysterious substance, thought to compose some 23% of the mass of our universe, is currently one of the most-sought substances in existence, the source of thousands of scientific papers and endless hours of speculation over the last half of the last century, despite the fact that it has not yet been directly detected. Now an analysis of 41 billion cosmic rays striking a state-of-the-art instrument called the Alpha Magnetic Spectrometer (AMS) particle detector aboard the International Space Station (ISS) may have come close to detecting dark matter.

Chimpanzee wars not due to human influence, says study

The Ngogo males have just killed a male from a neighboring group. After the male is dead, one of the Ngogo males leaps on the body of the dead animal. Image courtesy of John Mitan

Ngogo male chimps have just killed a male from a neighboring group. After the male is dead, one of the Ngogo males leaps on the body of the dead animal. Image courtesy of John Mitan

Lethal aggression is something that chimpanzees naturally do, the study says, regardless of whether human impacts are high or low

Why am I the one mosquitos always bite?

Photo credit: Macroscopic Solutions

Photo credit: Macroscopic Solutions

Here’s a Friday FAQ in honor of the passing of the summer.

Moon and Jupiter spectacular before dawn September 20


The waning crescent moon and the brilliant planet Jupiter still adorn the eastern predawn and dawn sky on September 20. If you’re up before dawn, you should be able to spot the star Regulus below the moon and Jupiter. Will you also see Venus? Maybe.

Dawn spacecraft to Ceres recovers after malfunctions

Artist's concept of Dawn spacecraft at asteroid Ceres.  Due to this setback, the craft is now scheduled to arrive at Ceres in April 2015, a month later than planned.  Image via NASA/JPL-Caltech/UCLA

Artist’s concept of Dawn spacecraft at dwarf planet Ceres. Image via NASA/JPL-Caltech/UCLA

NASA’s Dawn spacecraft – now in route to the dwarf planet Ceres, the largest object in the asteroid belt – unexpectedly went into safe mode on September 11, 2014, but it has now recovered. It is now due to reach Ceres in April 2015. That’s a month later than originally scheduled, thanks to this month’s setback.

Top 10 things you might not know about stars

The sun in extreme ultraviolet, false color green

The sun in extreme ultraviolet, false color green

Here’s a collection of 10 unexpected, intriguing facts about the stars of our universe – including our sun – that you probably didn’t know!