Archive

Archive for the ‘Ephemeris Program’ Category

02/12/2018 – Ephemeris – Ultima Thule is not what it first seemed

February 12, 2019 Comments off

Ephemeris for Tuesday, February 12th. Today the Sun will be up for 10 hours and 18 minutes, setting at 6:06, and it will rise tomorrow at 7:46. The Moon, at first quarter today, will set at 2:03 tomorrow morning.

This is just nuts. When the New Horizons spacecraft got around behind the body nicknamed Ultima Thule New Years Day and took a crescent view of it, they got a much thinner crescent than they thought. Instead of two round balls in contact, that they saw on approach they saw two very flattened lumps. From the approach side the body looked like a small ball sitting on a larger one. It turns out that the two components of Ultima Thule, named Ultima for the part with the greater diameter and Thule the smaller actually have the same mass. The spin axis runs right through the narrow neck that connects them. That’s their center of mass, or center of gravity. It’s sending planetary scientists back to the blackboard.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

First closeup of Ultima Thule

Ultima Thule on approach combining low resolution color image with the high-resolution monochromatic image shows the body in almost true color. Credit NASA/JHUAPL/SwRI.

Crescent Ultima Thule

The crescent of Ultima Thule, looking back after closest approach. Credit NASA/JHUAPL/SwRI.

Possible side view of Ultima Thule

Side view of Ultima Thule: Top as it was from the approach images. Bottoms as it actually appears to be. The blue dash lines the limits of what the flattening could be. Credit NASA/JHUAPL/SwRI.

Advertisements

02/11/2019 – Ephemeris – The stars Castor and Pollux

February 11, 2019 Comments off

Ephemeris for Monday, February 11th. Today the Sun will be up for 10 hours and 16 minutes, setting at 6:05, and it will rise tomorrow at 7:47. The Moon, 1 day before first quarter, will set at 12:57 tomorrow morning.

At 9 p.m. the constellation of Gemini the twins will be seen high in the southeast. The namesake stars of the two lads are the two bright stars at the top of the constellation. Pollux the pugilist, or boxer, is the lower of the two, while Castor, the horseman, is the other star, or rather a six star system. In telescopes two close stars may be seen each is a spectroscopic binary, meaning the lines of two stars can be seen in the spectrum. A faint nearby spectroscopic binary also belongs. Pollux, though a single star, does have at least one planet, over twice the mass of Jupiter orbiting the star at a distance somewhat greater than Mars is from the Sun. Pollux is 34 light years away while Castor is 50 light years away. Not too far away as stars go.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Gemini with Castor and Pollux

Gemini with Castor and Pollux. Created with Stellarium.

Castor star system

The Castor star system exploded in this JPL/NASA infographic.

02/08/2019 – Ephemeris – Sirius has a companion

February 8, 2019 Comments off

Ephemeris for Friday, February 8th. Today the Sun will be up for 10 hours and 7 minutes, setting at 6:01, and it will rise tomorrow at 7:52. The Moon, half way from new to first quarter, will set at 9:48 this evening.

Sirius is the brightest night-time star and is located in the south-southeast at 9 p.m. below and a bit left of Orion the Hunter. We’ve visited Sirius yesterday. But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. Its name is Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title. The tiny star was suspected as far back as 1834 due to Sirius’ wavy path against the more distant stars. Sirius and the Pup have 50 year orbits of each other. The Pup was first seen in 1862. The Pup was the first of a new class of stars to be discovered, white dwarfs. The Pup is a dying star with the mass of the Sun, collapsed down to the size of the Earth.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Orion's Belt points to Sirius

Orion’s Belt points to Sirius. Created using Stellarium.

Sirius' path

Sirius A & B’s path in the sky showing the wobble that betrayed the Pup’s presence. Credit Mike Guidry, University of Tennessee.

Sirius A and B

Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.

Categories: Ephemeris Program, stars Tags: , ,

02/07/2019 – Ephemeris – Siriusly, folks.

February 7, 2019 Comments off

Ephemeris for Friday, February 8th. Today the Sun will be up for 10 hours and 7 minutes, setting at 6:01, and it will rise tomorrow at 7:52. The Moon, half way from new to first quarter, will set at 9:48 this evening.

At 9 in the evening the great constellation of Orion the hunter can be seen in the south. Its large rectangle of bright stars is now upright, while in the center is a row of three stars, his belt. These stars tilt downward to the left to a very bright star merrily twinkling in the south-southeast. This star is called Sirius, also known as the Dog Star because it’s in the heart of Orion’s larger hunting dog, Canis Major. It is an arc light white star as seen in binoculars or telescope. It’s a neighboring star, just twice the distance of the closest star to the sun at 8.6 light years. It’s name, Sirius, has nothing to do with a dog, but is from the Greek meaning scorching for its brightness or sparkling, due to its intense twinkling.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Orion's Belt points to Sirius

Orion’s Belt points to Sirius. Created using Stellarium.

02/06/2019 – Ephemeris – Saturn is back, and a look at some other bright planets

February 6, 2019 Comments off

Ephemeris for Wednesday, February 6th. Today the Sun will be up for 10 hours and 2 minutes, setting at 5:58, and it will rise tomorrow at 7:54. The Moon, 2 days past new, will set at 7:47 this evening.

Let’s look at the planets for this week. Our only evening planet Mars will be in the southwestern sky this evening and will set at 11:50 p.m. It’s too far away to see much detail in a small telescope. In the morning sky we have Jupiter which will rise tomorrow at 4:17 a.m. It is second to Venus in brightness, and now is west of Venus. In small telescopes up to four of Jupiter’s moons are visible. Venus will rise at 5:17 a.m. tomorrow. In small telescopes it is a featureless slightly gibbous moon shape. Its phase will now grow more toward full as its size shrinks as it continues its long journey around and behind the Sun. Saturn is making an appearance in morning twilight rising at 6:12 a.m. tomorrow in the east-southeast.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Evening planets

Mars and the evening constellations tonight at 8 p.m. February 6, 2019. Note the faint planet Uranus near Mars.  They will appear only a degree apart next Wednesday night for a telescopic treat. Click on the image to enlarge. Created using Stellarium.

Morning Planets

Jupiter, Venus, and the rising Saturn at 7 a.m. tomorrow morning February 7, 2019. Created using Stellarium.

Telescopic Planets

Venus and Jupiter with the same magnification at 6 a.m. tomorrow morning February 7, 2019. Io is just peeking out on the lower left edge, though not quite showing up in this chart. Created using Cartes du Ciel (Sky Charts).

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on February 6, 2019. The night ends on the left with sunrise on the 7th. Click on the image to enlarge. Created using my LookingUp program.

02/05/2019 – Ephemeris – The Great Orion Nebula

February 5, 2019 Comments off

Ephemeris for Tuesday, February 5th. Today the Sun will be up for 9 hours and 59 minutes, setting at 5:56, and it will rise tomorrow at 7:56. The Moon, 1 day past new, will set at 6:47 this evening.

The closest star nursery to us is the Great Orion Nebula, 1,344 light years away give or take 20 light years. A light year is about 6 trillion miles, if you want to pace it out. It’s located in the constellation Orion’s sword that hangs below his belt. In as little as a pair of binoculars it shines by emission and reflection of the light of a clutch of four stars at its heart, that astronomers have called the Trapezium. These extremely hot baby stars are not destined to live long. Unlike the Sun’s 10 billion year life time these stars lifespan will be measured in millions of years. Yet do not mourn for them, Even now stars are forming in their dusty cocoons in the nebula. The Trapezium stars death will provide the material for new stars.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The lower part of Orion with the Great Orion Nebula. Created using Stellarium.

The lower part of Orion with the Great Orion Nebula. Created using Stellarium.

The Great Orion Nebula (M42) long exposure photograph

The Great Orion Nebula (M42) long exposure photograph by Scott Anttila. Includes all the sword stars.

Inner part of the Great Orion Nebula. Image by Scott Anttila

The Trapezium stars in the inner part of the Great Orion Nebula. Image by Scott Anttila

02/04/2019 – Ephemeris – Gemini the twins, or are they?

February 4, 2019 Comments off

Ephemeris for Monday, February 4th. Today the Sun will be up for 9 hours and 56 minutes, setting at 5:55, and it will rise tomorrow at 7:57. The Moon is new today, and won’t be visible.

Lets look at another of the winter constellations, and member of the Zodiac. The constellation Gemini, the Twins is visible high in the southeast, above and left of Orion the hunter at 9 p.m. The namesake stars of the two lads, will be at the left end of Gemini, nearly vertically aligned. Castor is on top, while Pollux is below. From them come two lines of stars extending toward Orion that outline the two. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus in the famous Leda and the swan affair and immortal, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the sky so they could be together forever.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Two ways of seeing Gemini

An animated look at two versions of the Gemini outlines. First the way I learned them as an outline of the lads. Second the way H. A. Rey from his popular 1952 book The Stars – A New Way to See Them, where the stars are connected to make stick figures. The Stellarium default for Gemini is that of H. A. Rey. My lines are due to a modification of the constellation lines table for the program. Created using Stellarium.