Asteroid 2005 YU55: See It For Yourself!


It’s already been stated several times here on Universe Today that 2005 YU55, a 400-meter-wide roughly spherical asteroid, will not pose any threat to Earth as it passes by on Tuesday, November 8… even though it will come within 80% of the distance to the Moon. Many experts have come forward to state this fact, including Don Yeomans of JPL’s Near-Earth Object Observation Program and Lance Benner, a radio astronomer with the Deep Space Network in Goldstone, CA.  But it will still be a notable event, being the first time since 1976 such a large object will pass so closely by our planet. So, with the eve of YU55’s approach upon us, let’s turn our curiosity toward another aspect of this cosmic visitation: how can we see it?

Unfortunately there are a couple of factors working against the casual observer being able to witness YU55’s pass. One: it’s a dark object. A very dark object. 2005 YU55 is a C-type asteroid, which means it is composed of carbonaceous material and is thus effectively darker than coal, reflecting less than 1% of the sunlight that it receives. It probably won’t be brighter than magnitude 10. (On the backwards-ranked scale of apparent magnitude, 6 is the limit of best visibility to the average human eye, while -1 or 0 would be a very bright star. Jupiter is about -3 right now, while the full moon would be -12.7. In a typical suburban neighborhood 3 or 4 is the limit of naked-eye visibility.)

And two: the Moon will be close to full on the night of the 8th, and YU55 will be headed in its direction. That sure won’t help visibility.

But, should you be located in a dark area, and should you have a 6″ or larger telescope at your disposal, you may want to give a go at spotting the asteroid that’s caused quite a fuss over the past few months for yourself. It won’t be a simple task, but it’s not impossible – and to help you out teacher, writer and astronomy enthusiast David Dickinson has posted an article about it on his blog, Astro Guyz.

Here’s an exerpt:

Closest approach to Earth occurs at 11:29 UTC/06:29 EST at about 202,000 miles distant, placing it high to the southwest for observers on the US Eastern Seaboard. At its closest approach, 2005 YU55 will glide along at one degree every 7 minutes, easily noticeable after a few minutes of observation at low power. I plan to target selected areas with my GOTO mount, sketch the field, then watch for changes. I may also take some wide-field piggyback stills with the DSLR, but mostly, this one will just be fun to watch.

Visually tracking a Near-Earth asteroid can be thrilling to watch; for example, I’ve actually seen 4179 Toutatis years ago show discernable movement after tracking it for a few moments in the eyepiece!

– David Dickinson

Wide field finder of 2005 YU55 from sunset until 8:30PM EST.

The asteroid will pass through the constellations Aquila, Delphinus, and Pegasus as it heads westward. Interestingly, 2005 YU55 passes within a degree of Altair centered on 6:07:30PM EST only 27 minutes after local sunset, and also makes a very close pass of the star Epsilon Delphini during closest approach. These both make good visual “anchors” to aim your scope at during the appointed time and watch. Keep in mind, the charts provided are rough and “Tampa Bay-centric…”

On an approach as close as this one, two factors muddle the precise prediction coordinates of the asteroid; one is the fact the gravitational field of the Earth will change the orbit of 2005 YU55 slightly, and two is that the position will change due to the position of the observer on the Earth and the effect of parallactic shift. Many prediction programs assume the Earthly vantage as a mere point in space, fine for positioning deep sky objects but not so hot for ones passing near the planet. A good place to get updated coordinates is JPL Horizons website which lets you generate an accurate ephemeris for your exact longitude latitude and elevation.

David goes on to add:

2005 YU55 will pass our Moon at 8 AM Universal Time on November 9th at a distance only marginally closer than it did the Earth, at 140,000 miles. Interestingly, it also transited Sun on November 3rd as seen from the Moon, but would have appeared <1” in size, a tough target for any would-be lunar-based observer. Its next close predicted passage of the Earth won’t be until 2056 at nearly 3 times the distance.


Excellent information… many thanks to David for sharing with us! (You can read the full article on his website here.) And if you do witness the pass of this asteroid and somehow manage to get some photos of it, you can share them on the Universe Today Flickr group… they may be featured in an upcoming article!

Read more about 2005 YU55’s close pass by Earth tomorrow.

Charts and excerpts by David Dickinson, created with Starry Night and Paint.


22 Replies to “Asteroid 2005 YU55: See It For Yourself!”

  1. Why can’t I opt out of the “Recommended For You” popup that appears on every story? It just ignores my “saved” preference and proceeds to recommend stories for EVERY article I read as I proceed down the page(and this is without my clearing the cache on my FF browser). This is a MAJOR annoyance! Please fix or preferably remove this widget.

    1. I agree. This is extremely annoying. If it would actually remember my preference for it to leave me the hell alone while I read the article, I could live with it.

      1. Constantly having a window in the lower right corner of the screen growing and shrinking every minute or so is the annoyance. At least, it is when the user has selected the “opt out” option for it.

    2. Yo Jon, install NoScript in your Firefox browser, and then configure the “Options” on what to “Allow”* or “Forbid”. That should relieve your annoyance!

      *Of course, you will need to “Allow” and in order to see and/or submit comments. (Duh!)

      1. I just tried it with the “AdBlockPlus” Add-On (also something which is kind of mandatory for Firefox). It seems to block that annoyance (yes, it annoys!). I hope it works, otherwise I’ll get back to your proposal.

      2. Just to say it: My way also works quite nicely, up to now.

        Nonetheless, I also vote for deleting it entirely from this website!

      3. Yo William, what browser are you using? If it’s Google Chrome, you can install ScriptNo, which gives NoScript’s functionality to Chrome.

    3. Errgh. Simple and clean website design is always best. University today keeps moving in the wrong direction with this. I dislike the widget a lot.

      1. After so many days of reporting that that things i frustrating annoying, it is still there. It always recommends things that I already ready! And it completely ignores my thing to shut it down.

        yes I could disable JavaScript but a stupid popup should not force me to do such a thing.

  2. Yo Jason, at the second paragraph, in the first line, as the context is plural, it should be there are, not “there’s”.

  3. The times in the image caption are wrong. Should say 23:03 – 23:12 UTC. Also the chart location needs to be stated. Parallax will effect the position of the asteroid as it is close to the Earth.

  4. The Lord’s Little Helper
    Luke 21:25
    There will be signs in the Sun, Moon and Stars. On the Earth, Nations will be in anguish and perplexity
    at the roaring and tossing of the sea.

    The time will come very soon when all on Earth will look to the Heavens above.

    Lord i Pray that we stay One Nation Under GOD, and United that all
    should be Free to read from the Bible the word of our Lord.

    The wicked will not stop till it is to late for them all if only they
    would read the Bible and get to know Jesus and want to go to Heaven Not Hell.

    All that give their heart to the Lord and Read The Bible
    and tell his Word to others will live forever. In Heaven

    But if from thence thou shalt seek the LORD thy GOD, thou shalt find him,
    if thou seek him with all thy Heart and with all thy Soul.

    May our Lord Jesus Christ and GOD the Father that is in Heaven,
    Guide and Watch over us.

    In this time of TRIBULATION, Strengthen your Faith, and encourage
    all to Pray for their Souls. The Strong in the Word of our Lord will Now
    Help the World and be the disciples of our Lord’s Word.

    Through out History Many have tried to wipe Jesus and the good from our history books.
    Read the Bible Jesus will Bless you more then i can.

    United We Will Always Stand That
    In GOD We Trust
    True Patriots

    The Lord’s Little Helper
    Paul Felix Schott

    Read The BIBLE
    John 8:12-31
    Mark 10:17-30

    2 Peter 3:10
    But the day of the Lord will come like a thief,
    in which the heavens will pass away with a roar and the elements will be destroyed with
    intense heat, and the earth and its works will be burned up.

    November 2, 2011

    1. Job 5. 1-2 “Call now; is there anyone who will answer you? To which of the holy ones will you turn? Surely vexation kills the fool, and jealousy slays the simple.”


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