Cranbrook Observatory

The observatory is open every Friday/Saturday from 8:30 - 10pm during daylight savings and 7:30 - 10pm during standard time, weather permitting. It is also open the first Sunday of the month from 1 - 4pm for safe viewing of the sun, weather permitting. Observatory hours are subject to change based upon the current or expected weather conditions. For specific information about observatory hours, please call ahead at 248 645.3200, and press 0.

NSN LogoThe Cranbrook Observatory will on occasion be broadcasting online using This site is for amateur astronomers who like to view and share the wonders of the night and daytime skies. You will be able to create a user account, free of charge, or just sign in as a guest user. Find "Cranbrook Observatory" on the list of available broadcasters to see virtually through our telescopes and sometimes hear a presentation from our astronomers!

Lunt Telescope

Planewave CDK 20"Three new telescopes, architectural changes in the viewing space, a new dome, and compatibility with the planetarium will create an experience unparalleled anywhere in the Midwest. The main telescope, a remote controllable 20-inch CDK research grade system, will be partnered with 6-inch Takahashi refractor and a Lunt solar telescope for better viewing capabilities and even live observation of the Sun. In addition, high quality CCD image cameras will enable real- time recording and conversion of images into digital photos for use on the planetarium dome. These cameras also will be operable from the planetarium.

TOA-150Part of a generous gift from the Mike and Adele Acheson family, the observatory improvements complete the total renovation of the astronomy infrastructure at the Institute started last year with upgrades to the planetarium. Since re-opening in October, The New Acheson Planetarium has offered visitors a 360 degree aural experience that delivers images that are three times brighter, crisper and more color saturated than before. In addition, a “green” lighting system for the projection of any color in the spectrum for greater visual effects capabilities, new sound systems and technology deliver the most intense planetarium experience in southeast Michigan.


The Hidden Costs of Light Pollution

A new video in the Hidden Costs series that takes a look at the detrimental effects of light pollution on our mental and physical health, species' natural habits, and our ability to see starscapes.

Created by:

The Sun & Moon

Lunar Phase

Solar Activity

Will the sky by clear?
Below is a link to an indicator that attempts to show at a glance when, in the next 48 hours, clear and dark skies are expected for Cranbrook Institute of Science.

The forecast data comes from a numerical weather model run by Canadian Meteorological Centre.

Click on the link then read from left to right. Locate a column of blue blocks. That is when the sky will likely to be clear and dark.

Cranbrook Institute of Science Clear Sky Clock

George Booth Historically, Cranbrook's Observatory began in 1927, when George G. Booth was developing Cranbrook as a cultural and educational complex. Many people were involved in the project, but Judge Henry Schoolcraft Hulbert was one of the most outstanding.

Judge Hulbert was associated with the courts of Wayne County for 44-years. In 1887, at the age of 18, he built his own telescope and observatory near the present Wayne State University campus, and developed an excellent working knowledge of the sky.

Judge HulbertJudge Hulbert was a good friend of Mr. Booth and because of his enthusiasm for learning, became one of the original members of Cranbrook School's Board of Trustees. Hulbert persuaded Booth to include astronomy in the curriculum of the school and donated the use of his three-inch refracting telescope, and Hulbert, after consulting with Dr. Ralph Hamilton Curtiss, director of the University of Michigan Observatory, purchased a six-inch refracting telescope at a cost of $3,585. This instrument was set up in a converted silo on the Cranbrook School campus.

Robert McMathSoon after its installation, however, a major problem became apparent. The telescope's drive mechanism did not operate smoothly. Hulbert mentioned this to his friend Francis McMath, and McMath suggested that his son, Robert, who was also interested in astronomy, might be able to help. Robert McMath took the critical pieces to his shop and shortly had the telescope functioning smoothly.

When the new Saarinen-designed school buildings were completed, included was a unique observatory tower to house the instrument. Soon after it was installed various problems arose. Because the tower was attached to heated buildings below, warm air filled the observatory in winter causing air turbulence and poor viewing conditions. As moisture condensed, ice formed inside the dome. Smoke from nearby chimneys and traffic vibrations on Lone Pine Road added to the problem. Thus, Robert McMath and Judge Hulbert asked Mr. Booth to consider constructing another observatory elsewhere on the grounds. To their surprise Booth produced plans for an observatory incorporating a museum (Cranbrook Institute of Science). McMath was asked to be designer, supervisor and purchasing agent for the envisioned observatory. When the Cranbrook Institute of Science became a reality in 1930, as an institution independent of Cranbrook School, both Hulbert and McMath became trustees and associate curators of astronomy.

CIS ca 1935At the same time McMath and his father, with the help of Hulbert, were in the process of constructing their own observatory at Lake Angelus. They wanted to make motion pictures of celestial objects, a feat no other observatory had attempted. In working toward this goal, they discovered that existing clock-drives were not accurate enough for motion pictures, so McMath developed a mechanism which not only facilitated better guidance, but also permitted changes from one drive rate to another. The Lake Angelus observatory was completed in 1936 and produced films of solar phenomena that have been studied around the world. The observatory became part of the University of Michigan but has since been sold.

CIS clock driveThus, a McMath drive, identical to the one at Lake Angelus, was installed at Cranbrook Institute of Science.

Planning for the Kitt Peak facility began in 1953 when the National Science Foundation became interested in constructing a national observatory. Robert McMath, then nationally known for his innovations, was asked to head the advisory panel and collect information for the site. He also was asked to design a solar telescope and his revolutionary design incorporated special insulation, cold water pipes for cooling and fire-proof tileboard.

Judge Hulbert and Robert McMath maintained their keen interest in the Institute of Science as trustees for three decades, from its founding until their death in 1959 and 1962.