September 23, 2017

AstroEvent: ISS All Nite!

 

The ISS as seen from STS-130. (Image Credit: NASA).

The ISS as seen from STS-130. (Image Credit: NASA).

(Editor’s Note: Due to timeliness concerns for events mentioned, we nudged next week’s astro-event up to today!)

   After a long drought, the International Space Station (ISS) returns to the nighttime skies this week. And what a return it is; starting tonight on June 23rd, the ISS enters a phase in which it is illuminated by the Sun throughout the span of its orbit. This unique event continues for four days, and sighting opportunities abound. This is only possible within a few weeks surrounding the solstice season, and does not happen again this year. Generally, the farther north or south in latitude you are, the greater the sighting opportunities; areas such as northern Maine, for example, will see the ISS on every 90 minute pass throughout the night! This also produces a dilemma for residents of the ISS, as overheating is a major concern. To offset or minimize this effect, portions of the ISS can be angled to alternately “shade” sections and automated cooling and radiating devices are installed throughout. Now is a good time to spy this celestial outpost of humanity, as its brightness rivals Venus. Spaceweather.com, Orbitron and the NASA ISS website all provide sighting guides; you can even follow @twisst on twitter for sighting ops or our humble feed @Astroguyz if you live in the US Southeast. Our favorite pick for ISS tracking is Heavens-Above, a tried and time honored favorite… let us know of your ISS sighting success stories!

The Astroword for this week is Inclination. This is one of the essential perimeters that defines an orbit of a celestial body; usually an established and agreed upon 0° degree point is set based on the primary bodies’ rotation (as is the case for objects orbiting the Earth) or orbital plane (for objects orbiting the Sun). That is, the Earth’s orbit as traced out by the ecliptic establishes zero point inclination throughout our solar system. The fact that the illumination angle of the ISS changes is a direct result of its 51.6° degree inclined orbit with respect to the Earth’s rotational equator. This relatively high inclination was chosen to be easily achievable between U.S. and Russian launch sites. In order for the shuttle or any spacecraft to reach the ISS, it must match the same magical orbital inclination of 51.6° degrees.

29.10.09:Is Solar Activity on the Upswing?

Sunspot group #1029. (Credit: Global Osillation Network Group).

Sunspot group #1029. (Credit: Global Oscillation Network Group).

Our characteristically dormant Sun has shown signs of awakening from it’s year plus long slumber this week. Specifically, a new sunspot group has formed on the Earthward facing side, and is now rotating towards the limb. This is definitely part of the new solar cycle #24, as characterized by its reversed polarity. Thus far, this solar cycle has been off to a sputtering start, at best. All amateur scopes, be they hydrogen Alpha, Calcium K, or safely filtered white light are encouraged to watch as this “monster” sunspot rotates around this Sun’s limb. The group already shows the envelopment of a fine dark umbra embedded in a pale penumbra, and will hopefully throw some looping prominences up through the chromosphere as it rotates from view. If you do not have optical means, you can still follow the action via SpaceWeather (the link above) or the Solar Heliocentric Observatories’ (SOHO) website! Enjoy!

10.8.9: Will the Perseids Perform?

Are we in for a Perseid spike? (Credit: NASA/Spaceweather).

Are we in for a Perseid spike? (Credit: NASA/Spaceweather).

Set your alarm clocks; one of the best meteor showers of the year is about to gear up this week! The Perseid meteors are one of the most dependable annual showers of the summer season, with a typical zenithal hourly rate (ZHR) of up towards 60-100 per hour. This year however, we could be in for a treat; there is evidence that we may intercept a fresh stream shed by progenitor comet Swift-Tuttle in 1610. We have never passed through this particular stream before; predictions are trending towards a brief ZHR of up towards 200! Don’t forget, however, that ZHR is optimal; this assumes the radiant is directly overhead and that there is no light pollution. The shower peaks morning of Wednesday August 12th, although it would be worth it to peek at the sky a few days prior to see what we might be in for. This year, the timing actually favors the North American continent! Now for the bad news; the waning gibbous Moon will be rising just before midnight in the constellation Aries, and be about 63% illuminated. If this is your chief source of light pollution, try to position yourself for observing in a way that blocks the Moon behind a hill, peak of a roof, whatever is handy. The Perseids are a true treat because they occur in the northern hemisphere summer, when its generally pleasant to lay outside. And school’s still out, to boot! Be sure not to miss this one; the only observing equipment you need is your eyes. If you can convince a friend to observe with you in the wee hours, you can collectively cover more sky. The radiant is located in the constellation Perseus (hence the name) which will be high in the north east. And don’t forget the bug spray! [Read more...]

Astro-Event of the Week: 05.11.09: See STS-125 dock with Hubble!

First; the good news. This week’s potential launch of Atlantis on STS-125 for it’s much delayed servicing mission (the 4th and final) to the Hubble Space Telescope (HST) will provide spectacular views, both of the initial launch along the Space Coast of Florida and the dawn and dusk skies as it chases the orbiting observatory. Now for the bad; the current orbit of Hubble is positioned such that most of the northern hemisphere won’t see the action! The HST is inclined at a 28.5 degree orbit, far different than the normal 51.6 degree orbit the shuttle orbiters must attain to dock with the ISS.

[Read more...]

A Lunar Eclipse Update:

A quick update concerning tonight’s Lunar Eclipse; in the event of clouds at your location, the eclipse can be viewed live via webcast on several sites. [Read more...]